(001)-Textured Laser-Crystallized Silicon thin Films on Glass Substrates - Nerding, Melanie; Christiansen, Silke; Eßer, Gerd; Urmoneit, Uwe; Otto, Andreas; Strunk, Horst Paul (Materials Research Society Symposium - Proceedings, 2001)
We investigate the microstructure of polycrystalline silicon films (grain size, texture and grain boundary population) on glass substrates. These films are produced from amorphous silicon precursor layers by scanning the raw beam of a continuous wave Ar+- ion laser operated at a wavelength of 514 nm over the amorphous silicon thereby crystallizing it. The materials applicability for devices in large area electronics strongly depends on the orientation of the surface normal, the average grain size and the defect density and population. Transmission electron microscopy together with electron back-scattering diffraction analysis of the crystallized layers reveal grain widths of about 10 μm and grain lenghts of several 10 μm. Under certain processing conditions a preferred (001)-surface normal orientation (texture) forms. The grain boundary population is dominated in the textured films by coincidence boundaries, essentially twin boundaries of first and second order as well as Σ=5 boundaries. © 2001 Materials Research Society.
LFT Import::2019-07-15 (898)

1. Workshop Blechmassivumformung - Merklein, Marion; Bach, Friedrich-Wilhelm; Tekkaya, A. Erman (Meisenbach, 2013)

2. Workshop Blechmassivumformung - Merklein, Marion; Behrens, Bernd-Arno; Tekkaya, A. Erman (Meisenbach, 2013)

35th ICFG Plenary Meeting Helsinki - Kuzman, K.; Putz, Alexander (Wire, 2002)
LFT Import::2019-07-16 (1696)

36th Plenary Meeting of the ICFG in Columbus, Ohio, USA - Putz, Alexander (Wire, 2003)
LFT Import::2019-07-15 (961)

37th Plenary Meeting of the ICFG, Istanbul, Turkey 2004 - Putz, Alexander (Wire, 2004)
LFT Import::2019-07-16 (1062)

38th Plenary Meeting of the International Cold Forging Group - Putz, Alexander (Wire, 2005)
LFT Import::2019-07-16 (1206)

3-D-Fokuslagensteuerung für die Laserstrahlstrukturierung - Eßer, Gerd; Urmoneit, U.; Ziegenhaus, M. (Laser in der Elektronikproduktion & Feinwerktechnik - Tagungsband des 3. Erlanger Seminars LEF 2000. Erlangen 8.-9.3., 2000)
LFT Import::2019-08-05 (757)

3D-Kenngrößen zur Beschreibung von Feinblechoberflächen. - Pfestorf, Markus; Engel, Ulf; Geiger, Manfred (Blech, Rohre, Profile, 1996)
LFT Import::2019-07-15 (667)

3D-Kennwerte zur Beschreibung technischer Oberflächen. - Geiger, Manfred; Pfestorf, Markus; Engel, Ulf (Tagungsbund IX. Int. Oberflächenkolloquium Chemnitz, 1996)
LFT Import::2019-08-05 (653)

3D-Lichtschnittsensor zur Biegewinkelerfassung - Geiger, Manfred; Heckel, Werner (Blech, Rohre, Profile, 1993)
LFT Import::2019-07-15 (403)

3D Oberflächenanalyse bei Feinblechen - Geiger, Manfred; Pfestorf, Markus; Engel, Ulf (Stahl und Eisen, 1995)
LFT Import::2019-07-16 (1975)

3D-Oberflächenanalyse - Methoden, Kenngrößen, Anwendungen - Engel, Ulf; Neudecker, Thomas; Popp, Uwe (Materialwissenschaft und Werkstofftechnik, 2000)
LFT Import::2019-07-15 (752)

3D Sensor based Closed Loop Control System for Flexible Forming Processes - Hutterer, Angelika; Otto, Andreas; Geiger, Manfred (Proceedings of 7th International Fall Workshop, Vision, Modelling and Visualisation, 2002)
LFT Import::2019-08-05 (1701)

3D Sensor Data Processing for Advanced Reliabilty of flexible Forming Processes - Hutterer, Angelika; Otto, Andreas; Menzel, Thomas (Sheet Metal 2001, 2001)
LFT Import::2019-07-15 (825)

3D-Sensordatenverarbeitung zur Regelung von flexiblen Formgebungsprozessen - Menzel, Thomas; Hutterer, Angelika; Otto, Andreas (Idee-Vision-Innovation, 2001)
LFT Import::2019-07-15 (826)

3D-Surface Parameters and their Application on Deterministically Textured Sheet Metals - Pfestorf, Markus; Engel, Ulf; Geiger, Manfred (International Journal of Machine Tools and Manufacture, 1998)
LFT Import::2019-07-16 (1615)

3-Rollen-Schubbiegen zur flexiblen Herstellung freiformgebogener Rohrleitungen - Merklein, Marion; Geiger, Manfred; Hagenah, Hinnerk; Cojutti, Massimo (Zukunftstechnologien in Bayern, 2008)
LFT Import::2019-07-29 (257)

4.0 in metal forming - Questions and challenges - Hagenah, Hinnerk; Schulte, Robert Karl; Vogel, Manfred; Hermann, Jennifer; Scharrer, Hannes; Lechner, Michael; Merklein, Marion (Procedia CIRP, 2019)
The paper gives a view on perspectives for metal forming processes rising due to the industry 4.0 discussion and its consequences. The discussion starts with a view at aims pursued by introducing 4.0 into metal forming. From the results of this the needed data and required sensors are discussed as well as the potential of their introduction into current processes. At this point the processes in metal forming and their respective demands have to be taken into account as well. From here the step to the specific challenges, e.g. originating from the machine tools at hand, can be elaborated on.
CRIS-Team Scopus Importer:2019-05-17
Keywords: Digital manufacturing system; Lifecycle; Metal forming

40th Plenary Meeting of the Cold Forging Group - Weidel, Stephan (Wire, 2007)
LFT Import::2019-07-16 (1492)

4M Network of Excellence, Progress Report 2009 - Dimov, S. S.; Matthews, C. W.; Brousseau, Emmanuel; Bigot, Samuel; De Grave, A.; Fillon, B.; Weinzierl, M.; Engel, Ulf; Johander, P.; Jung, E.; Kirby, P. B.; Mattsson, L.; et al. (4M/ICOMM 2009, Proceedings of the Global Conference on Micro Manufacture, 2009)
This paper gives a brief overview of the activities of the 4M Network of Excellence during the last nine months of its funded period. The 4M Divisions summarise their activity and outline their plans to continue to working together in future. Finally a summary of achievements during the whole lifetime of the Network is given.
LFT Import::2019-08-05 (1580)
Keywords: Network of excellence

4. Workshop Blechmassivumformung - Merklein, Marion; Behrens, Bernd-Arno; Tekkaya, A. Erman (FAU University Press, 2019)
Das Buch enthält die Veröffentlichungen zu den Vorträgen im Rahmen des Workshops. Diese hatten die neuesten Ergebnisse aus dem DFG-geförderten Transregio 73 zum Inhalt. Die Themen umfassten hierbei sowohl Umformprozesse als auch Aspekte des Verschleißes, der Schädigung, Messtechnik sowie der Simulation. Schlaglichter zu den Beiträgen aus der Wirtschaft, welche die Nutzung der Erkenntnisse in verschiedenen kommerziellen Feldern darstellten, runden den Inhalt ab.<br

A basic study of the influence of surface topography on mechanisms of liquid lubrication in metal forming - Soerensen, C.G.; Bech, J.I.; Andreasen, J-L.; Bay, N.; Engel, Ulf; Neudecker, Thomas (CIRP Annals - Manufacturing Technology, 1999)
LFT Import::2019-07-16 (2006)

Abtragen unter Wasser - verbesserte Qualität bei der Lasermaterialbearbeitung - Roth, Stephan; Töpperwien, Almut (LEF 2000, Laser in der Elektronikproduktion & Feinwerktechnik, 2000)
LFT Import::2019-07-15 (801)

Acceleration of the Simulation of Laser Beam bending - Challenges and Possibilities - Komlodi, Attila; Otto, Andreas (Thermal Forming, Proceedings of the IWOTE'05, Strahltechnik, 2005)
LFT Import::2019-08-05 (1188)

Accumulative Roll Bonding: Forming Behavior, Tailored Properties and Upscaling Approach - Merklein, Marion; Böhm, Wolfgang (Advanced Materials Research, 2014)
The Accumulative Roll Bonding (ARB) process enables the manufacturing of high strength sheet metals with outstanding mechanical properties by repeated rolling. However, the significant increase in strength leads to loss in ductility, especially regarding aluminum alloys of the 6000 series. The low formability obviously limits the implementation of these sheet products for formed components in automotive applications. To enhance formability, a local short term heat treatment according to the Tailored Heat Treated Blanks technology is used. For the finite element based design of forming operations accurate information about the plastic behavior of these tailored materials is required. Therefore, different stress - strain paths are considered using the tensile test and the layer compression test. In this context, heat treated and non-heat treated specimens out of ARB processed AA6016 were tested at room temperature. With the experimental results true stress – strain curves and yield loci determined from different criteria and represented in a principal stress state were established. Regarding the experimental setup of the ARB process, an upscaling is essential for the production of sufficiently large strips to cut out blanks for the forming of components such as B-pillars. However, this requires the adaptation of the different process steps of the ARB process. In this context, the surface treatment before rolling of such large sheets is investigated, since it is particularly relevant for obtaining a strong bonding between the sheets. Another aspect is the investigation of the rolling process using the finite element analysis. In this regard, a thermalmechanical coupled simulation model of the roll bonding operation will be developed for the evaluation of different material combinations, different process temperatures and varying roller geometries. These investigations will enable the production of lightweight automotive components made of ARB processed high strength aluminum sheet metal with tailored properties.
EAM Import::2019-03-13

Accumulative Roll Bonding of precipitation-hardenable aluminum alloys of the 6000 series in a warm rolling process - Merklein, Marion; Herrmann, Jürgen (Proc. ROLLING Conference, 2016)
In several industrial fields there is a persistent trend to lightweight construction. An auspicious possibility to cope with this challenge is the application of high strength aluminum, produced by accumulative roll bonding (ARB). Key idea of the ARB approach, which was originally invented by Saito et al. (1998), is the subsequent stacking and rolling of sheet material in order to gain an ultrafine-grained microstructure. The grain refinement results from the high deformations and shear stresses during each cycle of ARB. At the moment aluminum alloys of the 6000 series are pre-heated and rolled at room temperature. Within this contribution sheets of an AA6014 alloy are manufactured in a warm rolling process for the first time. The aluminum sheets are characterized regarding their mechanical properties and in particular their flow behavior. Furthermore, the bond strength of the respectively last bonded layer is examined using T-peel tests. Both testing methods are carried out after two and four rolling cycles. Based on these investigations a process strategy for the production of multilayered sheets in a warm rolling process is derived.
EAM Import::2019-03-13

Accuracy of conventional FE-Models in Bulk-Forming of Micropins from Sheet Metal - Kraus, Martin; Hufnagel, Thomas; Merklein, Marion (Journal of Micro and Nano-Manufacturing, 2019)
LFT Import::2019-07-29 (2357)

Accuracy of Conventional Finite Element Models in Bulk-Forming of Micropins from Sheet Metal - Kraus, Martin; Hufnagel, Thomas; Merklein, Marion (Journal of Micro and Nano-Manufacturing, 2019)
The ongoing miniaturization trend in combination with increasing production and functional volume leads to a rising demand for metallic microparts. Bulk forming of microparts from sheet metal provides the potential for mass production of those components by an extensive simplification of the handling. The advantage of a high production rate contrasts with the disadvantage of a low utilization of material. In this context, it is necessary to investigate suitable measures to increase the material utilization. To save cost intensive trial and error tests, numerical analysis could be an appropriate method for a basic process investigation. In this work, a validation with experimental results in the macro- and microscale was used to investigate the eligibility of the finite element method (FEM) for a basic process analysis. For a high transferability, the finite element (FE) models were validated for various tribological conditions and material states. The results reveal that there is a high agreement of the experimental and numerical results in the macroscale. In microscale, conventional FEM shows inaccuracies due to the negligence of size effects in the discretization of the process. This fact limits the application of conventional FE-programs. Furthermore, the results show that lubricated and dry formed blanks lead to the same friction force and process result in the microscale. In addition, the basic formability of the prestrengthened pins in further forming stages was experimentally demonstrated.
CRIS-Team Scopus Importer:2019-05-02
Keywords: bulk microforming; friction; Microforming; micropart; size effects; validation

A Comparative Investigation Introducing Regularization Techniques in Linear Regression Models for Quality Prediction in Forming Technology - Vicaria, A.; Vogel-Heuser, B.; Krüger, M.; Merklein, Marion; Lechner, Michael (IEEE International Conference on Industrial Engineering and Engineering Management, 2024)
In this investigation, linear models used for quality prediction of a final product are compared and evaluated using data from a real manufacturing process in forming technology (i.e., flexible rolling process). Two alternative methods for simplifying the feature selection method for the quality prediction model of manufactured blanks are presented. This work proposes implementing L1 and L2 regularization techniques in the original regression model. The method is then evaluated based on model complexity and performance metrics using the final predictions. By comparing these indicators, the effectiveness and benefits of the proposed method are confirmed. A simplification in the model-building effort and feature selection process is developed while providing an efficient and comparable accuracy in the predicted quality of the manufactured blanks.
CRIS-Team Scopus Importer:2025-04-01
Keywords: feature selection; forming technology; regularization techniques

A concept for process-oriented interdisciplinary tolerance management considering production-specific deviations - Heling, Björn; Oberleiter, Thomas; Rohrmoser, Andreas; Kiener, Christoph; Schleich, Benjamin; Hagenah, Hinnerk; Merklein, Marion; Willner, Kai; Wartzack, Sandro (Proceedings of the 22nd International Conference on Engineering Design (ICED19), 2019)

A Contribution to the Optimisation of a Simple Shear Test - Merklein, Marion; Biasutti, Manfredi (Key Engineering Materials, 2009)
The finite element method is a widely used tool in sheet metal forming. The quality of the results of such an analysis depends largely on the applied constitutive model and its material parameters, which have to be determined experimentally. These data are relevant on the choice of the yield criterion among the wide range of options available in the commercial applications implementing the finite element method. Since the accuracy of material parameters estimation is therefore crucial, investigations were performed with an Al-Mg sheet alloy and a mild steel sheet to optimize a Miyauchi-based simple shear test. This method is one of the basic ways to investigate the plastic properties of a sheet metal up to large strains, which is very important for numerical analysis of sheet metal forming processes. Aim of the test is to determine the shear stress-strain correlation. In order to enhance the quality of the experimental results the detection of the deformation's field, trough an optical measurement system, and the methodology for its evaluation are focus of the present study.
LFT Import::2019-07-29 (195)
Keywords: Material testing; Simple shear

Adapted mechanical properties for improved formability of aluminium blanks by local induction heating - Kerausch, Michael; Merklein, Marion; Geiger, Manfred (Adapted mechanical properties for improved formability of aluminium blanks by local induction heating. Proceedings of the International Body Engineering Conference 2003 in Chiba, Japan, 2003)
In this paper a novel process sequence consisting of local induction heating followed by deep drawing of a precipitation hardenable aluminum alloy is presented and compared with conventional processing. Using an induction heating system, it is possible to change the mechanical properties of the 6xxx-series in a restricted area by influencing the precipitation structure. Hardness measurements and tensile tests characterize the conversion from the stable naturally aged condition T4 to reversible solution heat-treated conditions of AA6016 as function of temperature and time. This effect leads to a reduction of flow stress, which is used to design an initial material property distribution adapted for the subsequent deep drawing process. A process characterization study provides detailed information concerning induction heating parameters, to improve the deep drawing of cylindrical cups, which results in a decisive increase of the limiting drawing ratio. Accompanying the experimental investigations, a finite element analysis approach is realized as a process design and optimization tool. Copyright © 2003 SAE International.
LFT Import::2019-08-05 (997)

Adapted tool design for the cold forging of gears from non-ferrous and light metals - Rohrmoser, Andreas; Hagenah, Hinnerk; Merklein, Marion (International Journal of Advanced Manufacturing Technology, 2021)
Due to growing competitive pressure within the manufacturing sector, there have been increasing attempts to establish resource saving production methods in gear manufacturing within recent years. Cold forging offers the potential—in addition to a high material and energy efficiency—to produce gears with an excellent surface quality, increased hardness as well as a load adapted fiber orientation. With regard to the wide range of applications there is a broad demand for gear materials, ranging from high-strength steels to non-ferrous and light metals. The flow behavior of the material has a significant influence on the cold forging process. Therefore, no consistent process result is achieved when forming different materials. Challenges exist due to deficient die filling and poor resulting geometrical accuracy. In this contribution, material-specific challenges during the full forward extrusion of gears from non-ferrous and light metals have been identified and suitable tool-sided measures were derived. A validated numerical process model was used to determine the underlying mechanisms of action and to verify the derived measures. A reduced yield stress leads to inflow formation, insufficient die filling, and low achievable strain hardening, as well as gearing accuracy. The tool-sided measures achieved a significant increase of resulting die filling and gearing accuracy as well as the mechanical properties. That provides the basis for the production of ready-to-use gears from various metal materials.
CRIS-Team Scopus Importer:2021-02-05
Keywords: Cold forging; Gears; Light metals; Simulation; Tool design

Adaption des Ringstauchversuchs für die Untersuchung der tribologischen Bedingungen beim Fügen warmumgeformter Stähle mittels Schneidclinchen - Müller, Martin; Vierzigmann, Ulrich; Hörhold, R.; Meschut, G.; Merklein, Marion (9. Erlanger Workshop Warmblechumformung, 2014)
LFT Import::2019-08-05 (2054)

Adaption of tool surface for sheet-bulk metal forming by means of pressurized air wet abrasive jet machining - Freiburg, Dennis; Assmuth, R.; Carballo, R. Garcia; Biermann, D.; Henneberg, Johannes; Merklein, Marion (Production Engineering, 2019)
Surface structures are used for several applications in industry to enhance the characteristics of surfaces and therefore processes. One example is the Sheet-bulk metal forming process which combines the advantages of bulk and sheet metal forming. Due to the complex material flow and load, the tool surfaces do need adapted tribological properties. High feed milled surface structures have been used in the past to control the material flow of the sheets. But due the high stresses appearing, the surfaces show a running-in behavior which altereds the tribological conditions. Within this study, a pressurized air wet abrasive jet machining (PAWAJM) process is used for adapting the high feed milled surface in order to manipulate the tribological conditions. Therefore, the surfaces characteristics, residual stresses as well as the tribological effects were investigated. It is shown that the PAWAJM process can be used to modify the surface characteristics and thus the friction of the surface. In addition, it can be seen that residual compressive stresses are applied during the PAWAJM.
CRIS-Team WoS Importer:2019-02-21

Adaption of tribological behavior of a-C:H coatings for application in dry deep drawing - Häfner, Tom; Rothammer, Benedict; Tenner, Jennifer; Krachenfels, Kim; Merklein, Marion; Tremmel, Stephan; Schmidt, Michael; Schmidt, Michael (MATEC Web of Conferences, 2018)
Nowadays the sheet metal forming industry faces challenges regarding efficient usage of resources and sustainability. One strategy to increase the environmental friendliness is to abandon the application of lubricants. The direct contact between tool and workpiece leads to an intensive interaction which increases friction. Especially for deep drawing processes with long sliding distances, this causes distinctive wear. The tool sided application of carbon based coatings is a well-known approach to reduce friction and wear. Former studies have shown a beneficial behavior of hydrogenated amorphous carbon based coatings (a-C:H) to improve the tribological conditions in contact with steel sheets and aluminium alloys under dry conditions. Within this study the coating process and the resulting coating properties will be analyzed. Afterwards mechanical and laser based surface treatment processes prior and after the deposition process will be investigated to reduce the coating roughness. Different roughness values were achieved by varying the surface treatment processes. The laser based finishing enables a reduction of the Spk values by removing single roughness asperities. In order to identify the necessary process parameters for the laser treatment, an analytical model of the material removal was applied. The laser surface treatment achieved similar roughness characteristics compared to mechanical treatment. In this study the tribological behavior of a-C:H coated tools was analyzed under dry conditions within strip drawing tests. The tribological investigations revealed that for dry deep drawing of zinc coated DC04 a broader range of Spk values leads to acceptable tribological conditions whereas for AA5182 a smoother tool surface has to be ensured to prevent adhesion and utilize the full potential of a-C:H coatings.<br
Keywords: Tribology; Surface Modification; Dry Deep Drawing

Adaptive Beam Delivery for CO2 Laser Material Processing - Geiger, Manfred; Neubauer, Norbert; Hoffmann, Peter; Hutfless, Joachim (Laser Processing: Surface Treatment and Film Deposition, Proceedings of the NATO ASI, 1994)
LFT Import::2019-08-05 (601)

Adaptive Design of Aluminium Sheets for Deep Drawing Processes - Geiger, Manfred; Merklein, Marion (Production Engineering, 2002)
LFT Import::2019-07-16 (1721)

Adaptives Streckbiegen von Aluminiumprofilen - Geiger, Manfred; Sprenger, Axel (Blech, Rohre, Profile, 1998)
LFT Import::2019-07-16 (1597)

Adaptives Streckbiegen von Aluminium-Strangpreßprofilen - Sprenger, Axel (Friedrich-Alexander-Universität Erlangen-Nürnberg, 1999)
The use of the space frame concept in lightweight body construction in large series is made difficult by the strong fluctuations in properties of aluminum profiles, which lead to low reproducibility in conventional bending processes. For this reason, the foundations for an adaptive profile bending process are developed in the presented dissertation. With the developed control concept, profiles can be bent robustly in just one forming step, so that subsequent straightening and calibration processes can be dispensed with. The adaptive process control provides that the course of the tool reaction force against the travel path of the profile clamping units is recorded during the so-called bending phase. From this information, a value for the axial tensile stress that is optimally adapted to the properties of the respective profile can be determined as a controlled variable. The core of the adaptive forming process is a neural network that maps the relationship between the sensor data and the spring back behavior of the profile. The learning ability of the neural network also allows continuous improvement in the performance of process control in series production. Studies on various profile cross sections and bending radii have shown that the control strategy can be applied to almost all bending task

Adaptive Strahlführungen für CO2-Laseranlagen - Neubauer, Norbert (1997)
The aim of this thesis is the development of instructions for the planning of adaptive beam delivery for CO2 laser machines free from optical aberrations. The application of the results leads to the development and application of a processing head with variable focus position during 3D laser beam processing. Within the framework of the thesis a new strategy for the characterization of the beam propagation was developed. A Shack-Hartmann sensor was developed for the measurement of the surface deformation of reflective optics under real conditions in the beam delivery of a laser machine. The results are the input for a consecutive wave optical simulation of the beam propagation. Fundamental investigations of various types of adaptive beam delivery were performed to find the limits for the parameters of adaptive beam delivery. Results include values for the allowed angle of incidence and beam radius at the surface of an adaptive mirror and the accuracy of the mechanical adjustment of the beam delivery. An example for the application of the results is the development of a processing head with variable focus position. In combination with a focal length of the focussing optics of 200 mm a focus shift up to 18 mm is possible. A further application of the results of this thesis is the beam path compensation in industrial laser cutting machines with flying optic

ADDIMID - Eine neue Variante zur Laserstrahlaktivierung von 3D-MIDs - Roth, Stephan; Dietel, C.; Eßer, Gerd (PLUS, 2004)
LFT Import::2019-07-16 (1120)

Additive Fertigung eines hybriden Planetenträgers - Papke, Thomas; Bartels, Dominic; Hofmann, Harald; Mys, Ruslana; Schmidt, Michael; Merklein, Marion (Zeitschrift für wirtschaftlichen Fabrikbetrieb, 2021)
Additive Manufacturing of a Hybrid Planet Carrier. The opportunity of freedom in design of additive manufacturing is applied to a planet carrier. Additive manufacturing starts on a conventionally manufactured base body, which is part of the planet carrier. This enables increased stiffness compared to the conventional design. Torsion tests show that stiffness can be doubled. Compared to singular additive manufacturing, costs decrease due to the hybrid design by 6 % for higher lot sizes.
Created from Fastlane, Scopus look-up
Keywords: Additive manufacturing; Assembly; Hybrid parts; Innovative technologies; Lightweight design

Additive Fertigung für industrielle Anwendungen - Entwicklung einer Auswahlsystematik für Bauteile zur Generierung funktionalen Mehrwerts mittels additiver Fertigung - Papke, Thomas; Bartels, Dominic; Schmidt, Michael; Merklein, Marion; Gerhard, Daniel; Baumann, Jonas; Pitz, Indra (Industrie 4.0 Management : Gegenwart und Zukunft industrieller Geschäftsprozesse, 2020)
Durch hohe Gestaltungsfreiheit und den Entfall produktspezifischer Werkzeuge gewinnen additive Fertigungsprozesse im industriellen Umfeld immer stärker an Bedeutung. Mit der Ausnutzung der verfahrensspezifischen Vorteile gegenüber konventionellen Fertigungsverfahren kann ein Mehrwert für Bauteile und Produkte generiert werden. Allerdings stellt die Auswahl potenzieller Bauteile, die durch die additive Fertigung einen Mehrwert erhalten können, eine Herausforderung dar. Zu diesem Zweck wurde eine Auswahlsystematik erarbeitet, um das Potenzial zu quantifizieren. Darauf aufbauend wird ein Ansatz vorgestellt, mit welchem beginnend mit der Bauteilauswahl über die Bauteil- und Prozesskettengestaltung eine Bewertung des Mehrwerts möglich ist. Dieser wird abschließend auf ein Strukturbauteil eines Fahrzeugs angewendet.<br

Additive Manufacturing of Functional Elements on Sheet Metal - Schaub, Adam; Ahuja, Bhrigu; Butzhammer, Lorenz; Osterziel, Johannes; Schmidt, Michael; Merklein, Marion (Physics Procedia, 2016)
Laser Beam Melting (LBM) process with its advantages of high design flexibility and free form manufacturing methodology is often applied limitedly due to its low productivity and unsuitability for mass production compared to conventional manufacturing processes. In order to overcome these limitations, a hybrid manufacturing methodology is developed combining the additive manufacturing process of laser beam melting with sheet forming processes. With an interest towards aerospace and medical industry, the material in focus is Ti-6Al-4V. Although Ti-6Al-4V is a commercially established material and its application for LBM process has been extensively investigated, the combination of LBM of Ti-6Al-4V with sheet metal still needs to be researched. Process dynamics such as high temperature gradients and thermally induced stresses lead to complex stress states at the interaction zone between the sheet and LBM structure. Within the presented paper mechanical characterization of hybrid parts will be performed by shear testing. The association of shear strength with process parameters is further investigated by analyzing the internal structure of the hybrid geometry at varying energy inputs during the LBM process. In order to compare the hybrid manufacturing methodology with conventional fabrication, the conventional methodologies subtractive machining and state of the art Laser Beam Melting is evaluated within this work. These processes will be analyzed for their mechanical characteristics and productivity by determining the build time and raw material consumption for each case. The paper is concluded by presenting the characteristics of the hybrid manufacturing methodology compared to alternative manufacturing technologies.
Keywords: Laser Beam Melting; Additive Manufacturing; Titanium alloy

Additive Manufacturing of Tailored Blank for Sheet-Bulk Metal Forming Processes - Schulte, Robert Karl; Papke, Thomas; Lechner, Michael; Merklein, Marion (2020)

Additive und umformtechnische Fertigung hybrider Bauteile mit lokal angepassten Eigenschaften - Hafenecker, Jan; Rothfelder, Richard; Merklein, Marion; Schmidt, Michael (Abschlusskolloquium des SFB 814, 2023)
Das Teilprojekt B5 hat zum Ziel, die Kombination aus additiver Fertigung und Umformtechnik zur Herstellung von maßgeschneiderten, funktionalisierten und individualisierten Titan-Hybridbauteilen eingehend zu erforschen. Neben dem Blechgrundkörper werden die additiv gefertigten Elemente der Hybridbauteile umgeformt, um den Werkstoff gezielt zu verfestigen und lokale Unterschiede in den Eigenschaften einzustellen. Zusätzlich wird angestrebt, eine lokale Werkstoffmodifikation in den additiv gefertigten Elementen zu erreichen. Dies wird durch den ortsselektiven Eintrag von Zusatzstoffen in Kombination mit in situ Legierungsbildung während des Laserstrahlschmelzprozesses (LSS-M) ermöglicht. Diese Modifikation soll sowohl den Anforderungen der Umformung als auch den Anforderungen des Einsatzes der Bauteile gerecht werden und individuell angepasst werden könne

Adjusting Optimized Material Properties for Tailored Heat Treated Blanks - Merklein, Marion; Hung Nguyen, (Key Engineering Materials, 2011)
Aluminum alloys have great potential for lightweight construction. In order to achieve an optimized properties distribution for the forming operation and to enhance the formability of aluminum alloys, so called Tailored Heat Treated Blanks (THTB) are developed. In this context, this paper is about the local precipitation hardening of sheet metals for the application of THTB. By using a specific, short-term heat treatment via conductive heating plates the thermal induced hardening of the fast hardenable alloy AA6181PX is quantified and qualified. Considering the processibility of the local precipitation hardening for THTB, a process window for the heat treatment parameters is presented allowing a precise setting of the mechanical material properties.
EAM Import::2019-03-13

Advanced Approach to Evaluate Local Deformation Behaviour at Microscale - Geißdörfer, Stefan (Proceedings of the 2nd International Conference on New Forming Technology, 2007)
LFT Import::2019-08-05 (1495)

Advanced laser heat treatment with respect to the application for Tailored Heat Treated Blanks - Nguyen, Manh Hung; Merklein, Marion (Physics Procedia, 2010)
LFT Import::2019-07-29 (1769)
Keywords: Aluminum alloy; Laser heat treatment; Tailored Heat Treated Blanks

Advanced Numerical Modelling of Patchwork Blank Forming Processes - Lamprecht, Klaus; Geiger, Manfred (Proceedings of the 8th International Conference on Technology of Plasticity (ICTP), 09.-13.10., Verona, Italy, 2005)
LFT Import::2019-08-05 (1136)

Advanced process strategies for the hydroforming of complex structures - Geiger, Manfred; Celeghini, Martino; Novotny, Stefan (XIV Workshop on Supervising and Diagnostics of Machining Systems, 10-12 March 2003, 2003)
LFT Import::2019-08-05 (935)

Advanced rapid prototyping by Laser beam sintering of metal prototypes: design and development of an optimized laser Beam delivery system. - Geiger, Manfred; Coremans, Arjan; Neubauer, Norbert; Niebling, Frank (Proc. Of the Europto Series - Rapid Prototyping (1996), Frankreich : Besancon, 1996)
LFT Import::2019-08-05 (639)

A dynamic simulation scheme using Fuzzy Set Theory for the prediction of the efficiency of innovative manufacturing techniques - Menzel, Thomas; Geiger, Manfred (Proceedings of the CIRP International Seminar on Intelligent Computation in Manufacturing Engineering, 1998)
LFT Import::2019-08-05 (1610)

A Feature Based Approach for Simultaneous Engineering of Sheet Metal Components - Greska, Wolfgang; Hoffmann, Peter; Geiger, Manfred (Transactions of the North American Manufacturing Research Institution, 1993)
LFT Import::2019-08-05 (417)

Aktuelle Trends in der Laserstrahlmikrobearbeitung - Eßer, Gerd; Schmidt, Michael (Laser in der Elektronikproduktion & Feinwerktechnik - Tagungsband LEF 2003, 2003)
LFT Import::2019-08-05 (980)

Aktuelle Trends in der Laserstrahlmikrobearbeitung, Teil II: Verbindungstechnik, Feinwerktechnik, Mikromechatronik u.a. Trends - Eßer, Gerd; Schmidt, Michael (Laser, 2003)
LFT Import::2019-07-15 (989)

Aktuelle Trends in der Laserstrahlmikrobearbeitung, Teil I: Mikrotechnik, Halbleitertechnik, Aufbau- und Verbindungstechnik - Eßer, Gerd; Schmidt, Michael (Laser, 2003)
LFT Import::2019-07-15 (990)

Algorithmen zum simulationsbasierten, pulsgenauen Planen von Laserbestrahlungen - Klämpfl, F.; Hagenah, Hinnerk (Simulation und Visualisierung 2008. Proceedings of the 19th Conference on Simulation and Visualization (SimVis), 2008)
LFT Import::2019-08-05 (260)

Algorithms for Irradiation Planning in Medical Laser Applications - Klämpfl, F.; Schmidt, Michael; Hagenah, Hinnerk; Geiger, Manfred (Proceedings of the 5th CIRP International Seminar on Intelligent Computation in Manufacturing Engineering, 2006)
LFT Import::2019-08-05 (265)

Algorithms for Planning and Control of Laser Forming - Hagenah, Hinnerk; Plettke, Raoul; Geiger, Manfred (Proceedings of the IWOTE 08, 2008)
LFT Import::2019-08-05 (144)

Algorithms for pulsewise irradiation planning - Klämpfl, Florian; Hagenah, Hinnerk (Proceedings of the LANE 2007, 2007)
LFT Import::2019-08-05 (263)

A lightweight sensor ontology for supporting sensor selection, deployment, and data processing in forming processes - Vogel-Heuser, Birgit; Vicaria, Alejandra; Ji, Fan; Höfgen, Josua; Jäckisch, Manuel; Lechner, Michael; Merklein, Marion (Production Engineering, 2024)
In the era of smart manufacturing, modern manufacturing systems face high demands for enhancing process performance and reducing machine downtime. Sensors and process data are essential for successfully implementing data-driven approaches to guarantee robust and reliable process monitoring, tool conditioning, or quality assurance. However, the accuracy and performance of such approaches are highly dependent on the quality of the gathered sensor data and influenced by the implemented data acquisition and processing methods. For this purpose, this work proposes a lightweight sensor ontology to provide a comprehensive overview to characterize underlying relationships between the physical environment and the quality of the data sets. The extended sensor ontology, in combination with domain knowledge, aims to support engineers in fully exploiting the potential of sensor data to obtain trustworthy data sets in forming technologies. As a result, this approach can improve the implementation of automated and data-driven process monitoring of forming systems and tools.
CRIS-Team Scopus Importer:2024-05-24
Keywords: Data-driven methods; Forming processes; Ontology; Process monitoring; Sensor positioning; Sensor selection

Alloy design and adaptation for additive manufacture - Clare, A. T.; Mishra, R. S.; Merklein, Marion; Tan, H.; Todd, I.; Chechik, L.; Li, J.; Bambach, M. (Journal of Materials Processing Technology, 2022)
In this review the authors provide a comprehensive insight into additive manufacturing process mechanics which explore how thermodynamics give rise to characteristic microstructure and property. Discussion is then given over to how solidification microstructure is modified using processing conditions and utilisation of traditional casting methods which give rise to grain refinement and some cases ‘texture by design’. The review then makes observation and provides analysis on the typical material types reported in powder bed fusion and directed energy deposition. These are organised to efficiently highlight the key observations in terms of alloy creation and adaption with a specific focus on the relevant additive manufacturing technique. The emergent alloy families are also explored alongside the rapidly expanding topic of functionally graded alloys produced by the breadth of additive manufacturing techniques. The review concludes with a detailed critique of the state-of-the-art and an examination of where opportunities exist to advance the interdependency between process and emergent alloys exhibiting superior properties. The authors propose several areas worthy of consideration and attempt to provide inspiration for our community in the pursuit of new alloys and accompanying process designs for additive manufacturing.
CRIS-Team Scopus Importer:2021-10-08
Keywords: Additive manufacture; Alloy development; Directed energy deposition; Powder bed fabrication

Alternating Additive Manufacturing and Forming - An Innovative Manufacturing Approach - Papke, Thomas; Hafenecker, Jan; Römisch, David; März, Raphaela; Hentschel, Oliver; Bartels, Dominic; Schmidt, Michael; Merklein, Marion (Journal of Manufacturing and Materials Processing, 2023)
In this work, an innovative manufacturing approach that includes a fully linked and integrated manufacturing system consisting of a laser-based directed energy deposition (DED-LB/M) module and a forming press is presented. The alternating additive manufacturing (AM) process is based on a combination of a DED-LB/M process using a laser power of 600 W and a feed rate of 400 mm/min and a subsequent forming process, in which the structure is upset with a hydraulic press using a constant forming force of 500 kN in order to smooth the surface and influence the accuracy of the components. For the generation of a fundamental process understanding, a cuboid, basic shape was chosen as geometry for the investigations. The aim is to improve part properties by applying the process steps to generate part properties, which are superior to solely additive manufactured material. It is shown that the geometry of additive manufactured structures can be adapted, and the top surface can be smoothed due to the forming operation. The mean roughness value Rz decreases up to 50% after the forming operation. The hardness can be increased by work hardening. Of special interest is that the higher hardness can be kept up even though a further DED-LB/M process step and forming operation are applied to the additively manufactured and formed structure again. Finally, an analysis of the new manufacturing approach regarding its potential is give
Keywords: forming; additive manufacturing; DED-LB/M; process combination

Alternative characterization method for the failure behavior of sheet metals derived from Nakajima test - Kohl, Doris; Merklein, Marion (INTERNATIONAL DEEP-DRAWING RESEARCH GROUP CONFERENCE (IDDRG 2021), 2021)
CRIS-Team WoS Importer:2021-11-05

Alternative Strategien zum Laserstrahl-Mikroschweißen von optisch hoch reflektierenden Werkstoffen - Schmidt, Michael; Mys, I.; Jahrsdörfer, Bernd (Laser in der Elektronikproduktion & Feinwerktechnik LEF, 2003)
LFT Import::2019-07-15 (930)

Aluminiumlösungen aus maßgeschneidert wärmebehandelten Halbzeugen - Graser, Matthias; Degner, Julia; Böhm, Wolfgang; Merklein, Marion (Konstruktion, 2017)
LFT Import::2019-07-29 (2271)

Aluminium Tailored Heat Treated Blanks - Geiger, Manfred; Merklein, Marion; Vogt, Uwe (Annals of the German Academic Society for Production Engineering WGP, 2009)
LFT Import::2019-08-05 (1567)

Aluminum tailored heat treated blanks - Geiger, Manfred; Merklein, Marion; Vogt, Uwe (Production Engineering, 2009)
Tailored Heat Treated Blanks (THTB) are blanks, which exhibit locally different material properties optimized for the succeeding sheet metal forming process. The distribution of the material properties is obtained by a local, short-term heat treatment. As a result of the optimized property gradients in the sheet metal's plain, THTB allow enhancing the forming limits significantly. The research work covered in this paper focuses on THTB made out of aluminum alloys. The article presents the microstructural mechanisms due to a short-term heat treatment as well as design principles for the heat treatment layout for THTB made out of AlMgSi alloys and ultra-fine grained (UFG) aluminum alloys produced by the Accumulative Roll Bonding process.
EAM Import::2019-03-13

A Method for the Layer Compression Test Considering the Anisotropic Material Behavior - Merklein, Marion; Kuppert, Andreas (International Journal of Material Forming, 2009)
The layer compression test is used in the field of material characterization to determine the onset of yielding and the hardening behavior of a sheet metal within uniaxial compression loading. For testing anisotropic materials the experimental setup has to be adjusted and the evaluation has to be adapted. This could be achieved with the installation of a second optical strain measurement system to get data of both symmetry axes. In the following paper the experimental procedure with two strain measurement systems and the evaluation methodology regarding the two sets of data will be presented and validated with experimental results. The advantage of the layer compression test is discussed in comparison with the results of a standard tensile test. © Springer/ESAFORM 2009.
LFT Import::2019-08-05 (292)
Keywords: Anisotropy; Layer compression test; Material characterization

A methodology for the application of virtual evaluation methods within the design process of cold forged steel pinions - Rohrmoser, Andreas; Heling, Björn; Schleich, Benjamin; Kiener, Christoph; Hagenah, Hinnerk; Wartzack, Sandro; Merklein, Marion (Proceedings of the 22nd International Conference on Engineering Design (ICED19), 2019)

An advanced approach in simulation of microforming processes - Geißdörfer, Stefan (Proceedings of the 1st International Conference 4M, 2005)
LFT Import::2019-08-05 (1185)

Analyse der Abbildbarkeit des dehnungsabhängigen Bauschinger-Effekts mithilfe istrop-kinematischer Modelle - Rosenschon, Martin; Merklein, Marion (Tagungsband XXXV. Verformungskundliches Kolloquium, 2016)
LFT Import::2019-08-05 (2164)

Analyse des Einflusses der tribologischen Eigenschaften auf die Tiefziehbarkeit metallischer Blechwerkstoffe nach dem Durchlauf einer Ziehsicke - Merklein, Marion; Schmid, Harald (2021)

Analyse des tribologischen Einsatzverhaltens von modifizierten Werkzeugoberflächen - Wild, Thomas; Merklein, Marion (Aktuelle Entwicklungen im Bereich der Umformtechnik, 2020)

Analyse lokaler Kurzzeitwärmebehandlungsmethoden zur Verbesserung des Umformverhaltens und der Bauteileigenschaften von Aluminiumstrangpresshohlprofilen - Graser, Matthias (Friedrich-Alexander-Universität Erlangen-Nürnberg, 2023)
The key issues of the 21st century, such as climate change and electromobility, pose major challenges in the automotive industry. In particular, the continuously increasing vehicle weight, which leads to higher energy consumption, plays a crucial role here. Therefore, one of the most important parameters for improving the ecological balance and increasing the range of modern vehicle concepts is lightweight construction. The increased use of lightweight materials such as aluminum is one way of realizing this concept. However, their low formability compared to ductile steel materials stands in the way of the complete use of aluminum alloys. Therefore, within the scope of this work, a methodology for expanding the shaping limits of extruded aluminum hollow profiles in the bending process is to be developed on the basis of the already known technology for the production of heat-treated aluminum blanks. The basis for this is the development of a basic understanding of the relationships between laser-induced temperature distribution, the resulting locally changed mechanical properties and their influence on the material flow in the bending process. These findings are used to improve the formability and component properties of the hollow profiles and thus further expand their possible areas of applicatio

Analyse und Beschreibung des mechanischen Werkstoffverhaltens von presshärtbaren Bor-Manganstählen - Stöhr, Thomas (Friedrich-Alexander-Universität Erlangen-Nürnberg, 2012)
In the scope of this work was the improvement of the accuracy of FE models with regard to forming processes following the temperature-time profile of the hot stamping process. The focus of the investigations was on the determination and description of the forming behavior of boron manganese steels in dependency of process relevant influencing factors. Furthermore a methodology for the determination of true stress-strain curves at elevated temperatures in the layer compression test had been determined, enabling the rating of the stress state on the forming behavior of boron manganese steels. The distinctive improvement of the quality of the FE modeling of hot stamping processes utilizing the knowledge of this work had been shown in a comparison of the sheet thickness evolution of a numerically mapped and a experimentally formed componen

Analyse und Klassifizierung von Blechteilen - Geiger, Manfred; Greska, Wolfgang (Technica, 1993)
LFT Import::2019-07-15 (395)

Analysing resistance element welding with upset auxiliary joining steel-elements under shear load - Meinhardt, Mario; Endres, Martin; Graf, Marcel; Lechner, Michael; Merklein, Marion (Procedia Manufacturing, 2019)
The multi-material-design, as one common lightweight design strategy, has to be intensified in order to reach climate-goals and to comply with exhaust gas emission limits. For joining sheet metal parts of different materials, enhanced joining technologies are used, which are specific for each application case. Within this paper, resistance element welding joints of sheet metals in shear load tests are investigated. The resistance element welding process with upset auxiliary joining steel-elements is a possibility for joining multi-material sheet metal parts, using the standard process of resistance spot welding. In order to assess the potential of this joining process, it is necessary to determine the load-bearing behaviour under shear load by shear tensile tests. The objective of this paper is to analyse the maximum shear strength for resistance element welding specimen with upset steel-elements in aluminium carrier sheets of different thicknesses. The geometry of the test specimen is adapted to resistance element welding process conditions. Failure behaviour under shear load is analysed and related to the applied upset elements. Finally, the maximum shear load strength of resistance element welding joints are presented and compared to similar joining technologies.
CRIS-Team Scopus Importer:2019-12-20
Keywords: Joining Technology; Lightweight; Multi-Material; Resistance Element Welding; Shear Tensile Test

Analysing the DMLS-Process by a Macroscopic FE-Model - Niebling, Frank; Otto, Andreas; Geiger, Manfred (Solid Freedom Fabrication Symposium, 2002)
LFT Import::2019-08-05 (1703)

Analysis and Classification of Sheet Metal Components - Geiger, Manfred; Greska, Wolfgang (Production Engineering, 1993)
LFT Import::2019-07-15 (396)

Analysis and Modeling of Laser Beam Melt Ablation - Cser, Adrienn Orsolya; Otto, Andreas (AMST 05: Advanced Manufacturing Systems and Technology: Proceedings of the 7th International Conference, 2005)
Laser beam melt ablation as a non-contact process offers several advantages compared to conventional processing mechanisms. During ablation the surface of the workpiece is molten by the energy of a CO2-laser beam. This melt is then driven out using the momentum transfer from an additional process gas flow. Although the idea behind laser beam melt ablation is rather simple, the process itself has a major limitation in practical applications: with increasing ablation rate, the surface quality of the processed workpieces declines rapidly. To find an explanation, and to be eventually be able to control the process thorough analyses are necessary. For this, in addition to the measurements of the processed surfaces also the optical process emissions have been recorded and analyzed. These data show a pronounced 1/f-noise-like behavior, which suggests the existence of intermittency during processing.
LFT Import::2019-08-05 (1176)
Keywords: Control; Laser ablation; Modeling

Analysis of combined extrusion micro coining process to manufacture microstructured tappets - Zahner, Michael; Merklein, Marion (Procedia Manufacturing, 2018)
In times of enhanced functional integration of machine elements the combination of forming processes offers an opportunity to increase the efficiency of the manufacturing process. Due to mutual interactions combining different forming operations a comprehensive analysis of the processes is necessary especially regarding micro forming processes. Within this study a combined extrusion micro coining process to manufacture microstructured tappets was investigated. The results reveal that the achieved homogeneity on tappet surface is mainly influenced by the microstructure layout applied on the tool components, due to locally widely varying material flow in the coining region.
LFT Import::2019-07-29 (2334)
Keywords: Combined forming process; Geometrical accuracy; Micro Coining; Microstructures; Tribology

Analysis of Distributed-Ledger-Technology for the Exchange of Design, Production and Simulation Data in Roll Forming - Kohl, B.; Krueger, M.; Dietl, T.; Lechner, Michael; Trunzer, E.; Merklein, Marion; Sedlmaier, A.; Vogel-Heuser, B. (INTERNATIONAL DEEP-DRAWING RESEARCH GROUP CONFERENCE (IDDRG 2022), 2022)
CRIS-Team WoS Importer:2023-01-20

Analysis of Effectiveness of Locally Adapted Tribological Conditions for Improving Product Quality in Sheet-Bulk Metal Forming - Löffler, Maria; Gröbel, Daniel; Engel, Ulf; Andreas, Kolja; Merklein, Marion (Applied Mechanics and Materials, 2015)
LFT Import::2019-07-29 (2099)

Analysis of Forming Limits in Sheet Metal Forming with Pattern Recognition Methods. Part 1: Characterization of Onset of Necking and Expert Evaluation - Affronti, Emanuela; Jaremenko, Christian; Merklein, Marion; Maier, Andreas (Materials, 2018)
In automotive manufacturing, high strength materials, and aluminum alloys are widely used to address the requirement of ensuring a lightweight car body and correspondingly, reducing pollution. In this context of complexity of materials and structures, an optimized process design with finite element analyses (FEA) is mandatory, as well as a correct definition of the material forming limits. For this purpose, in sheet metal forming, the forming limit curve (FLC) is used. The FLC is defined by the onset of necking. The standard evaluation method according to DIN EN ISO 12004-2 is based on the cross-section method and assumes that the failure occurs due to a clear localized necking. However, this approach has its limitations, specifically in the case of brittle materials that do not exhibit a distinct necking phase. To overcome this challenge, a pattern recognition-based evaluation is proposed. Although pattern recognition and machine learning techniques have been widely employed in the medical field, few studies have investigated them in the context of analyzing metal sheet forming limits. The application of pattern recognition in metal forming is subject to the exact definition of the forming behaviors. Thereby, it is challenging to relate patterns on the strain distribution during Nakajima tests with the onset of necking for the FLC determination. Thus, the first approach was based on the crack evaluation, since this class is well-defined. However, of substantial interest is the evaluation of the general material instabilities that precede failure. Therefore, in the present study, the analysis of the material behavior during stretching is conducted in order to characterize instability classes. The results of Nakajima tests are investigated using an optical measurement system. A conventional pattern recognition approach based on texture features, considering the outcomes of expert interviews for the definition of classes is used for the FLC determination. Moreover, an analysis of the validity of the supervised learning is conducted. The results show a good prediction of the onset of necking, even for high strength materials with a recall of up to 92%. Some deviations are observed in the determination of the diffuse necking. The discrepancies of the different experts' prognoses highlight the user-dependency of the FLC, suggesting further investigations with an data-driven approach, could be beneficial.
LFT Import::2019-07-29 (2319)
Keywords: Forming limit curve; Machine learning; Pattern recognition; Sheet metal forming

Analysis of Forming Limits in Sheet Metal Forming with Pattern Recognition Methods. Part 2: Unsupervised Methodology and Application - Jaremenko, Christian; Affronti, Emanuela; Maier, Andreas; Merklein, Marion (Materials, 2018)
The forming limit curve (FLC) is used in finite element analysis (FEA) for the modeling of onset of sheet metal instability during forming. The FLC is usually evaluated by achieving forming measurements with optical measurement system during Nakajima tests. Current evaluation methods such as the standard method according to DIN EN ISO 12004-2 and time-dependent methods limit the evaluation range to a fraction of the available information and show weaknesses in the context of brittle materials that do not have a pronounced constriction phase. In order to meet these challenges, a supervised pattern recognition method was proposed, whose results depend on the quality of the expert annotations. In order to alleviate this dependence on experts, this study proposes an unsupervised classification approach that does not require expert annotations and allows a probabilistic evaluation of the onset of localized necking. For this purpose, the results of the Nakajima tests are examined with an optical measuring system and evaluated using an unsupervised classification method. In order to assess the quality of the results, a comparison is made with the time-dependent method proposed by Volk and Hora, as well as expert annotations, while validated with metallographic investigations. Two evaluation methods are presented, the deterministic FLC, which provides a lower and upper limit for the onset of necking, and a probabilistic FLC, which allows definition of failure quantiles. Both methods provide a necking range that shows good correlation with the expert opinion as well as the results of the time-dependent method and metallographic examinations.
LFT Import::2019-07-29 (2327)
Keywords: Forming limit curve; Machine learning; Pattern recognition; Sheet metal forming

Analysis of fundamental dependencies between manufacturing and processing Tailored Blanks in sheet-bulk metal forming processes - Schulte, Robert Karl; Hildenbrand, Philipp; Vogel, Manfred; Lechner, Michael; Merklein, Marion (International Conference on the Technology of Plasticity, ICTP 2017, 17-22 September 2017, Cambridge, United Kingdom, 2017)
LFT Import::2019-08-05 (2232)
Keywords: Cold forming; Deep drawing; Tailored Blank

Analysis of material behaviour in experimental and simulative setup of joining by forming of aluminium alloy and high strength steel with shear-clinching technology - Müller, Martin; Hörhold, Réjane; Merklein, Marion; Meschut, Gerson (Advanced Materials Research, 2014)
LFT Import::2019-07-29 (2020)
Keywords: Clinching; FEM; Joining by forming; Lightweight design; Multi-material mix

Analysis of microbending of CuZn37 brass foils based on strain gradient hardening models - Li, He-Zong; Dong, Xiang-Huai; Shen, Yu; Zhou, Rui; Diehl, Alexander; Hagenah, Hinnerk; Engel, Ulf; Merklein, Marion; Cao, Jian (Journal of Materials Processing Technology, 2012)
Microbending experiments of brass foils were conducted and demonstrated clear size effects, i.e., the normalized bending moment increased with the reduction of foil thickness. The experiments were modeled using the classical plasticity model and three strain-gradient plasticity models. A modified Nix-Gao model was proposed to consider the number of twins across the thickness direction in strain hardening. It was found that the proposed model could better predict the normalized bending moment for both fine-grain and coarse-grain foils and the proposed equation for material intrinsic length could better capture the physics of material deformation. Furthermore, micro-hardness distributions in the bending area were measured and obvious lower-hardness region was found in the middle layer of fine-grain foils instead of coarse-grain foils. This indicates that the modified Nix-Gao model and the assumption of fully plastic bending worked better for coarse-grain foils than for fine-grain foils. © 2011 Elsevier B.V. All rights reserved.
LFT Import::2019-07-29 (1779)
Keywords: Bending moment; CuZn37 brass; Material intrinsic length; Microbending; Strain gradient

Analysis of Multiaxial Tensile Stresses in Cold Forging Tools - Killmann, Martin; Merklein, Marion (Lecture Notes in Mechanical Engineering, 2024)
Tools have a key role in cold forging as they directly influence part quality and process economics. High loads from the contact pressure exhibited by the workpiece are a major challenge regarding tool life. In complex geometries, tensile die stresses are concentrated in local areas and oriented both in axial and tangential directions. This superposition of loads leads to fatigue failure at the stress peaks. Since the interactions of multidirectional tensile stresses in cold forging tools have not been investigated in previous investigations, this paper aims to better understand the formation of local stress concentrations in axial and tensile directions as well as the possibilities to influence them. As tool loads in critical areas are difficult to measure during the process, simulation plays an important role in the evaluation of die stresses. Therefore, a model process with multiaxial tool stresses is simulated and the simulation results are compared to experimental values in order to validate the model. The simulation is then used to analyse the die load depending on the prestressing system.
CRIS-Team Scopus Importer:2024-09-13
Keywords: Cold forming; Die; Stress

Analysis of Production Limits in Manufacturing of Micro Coined Structures - Zahner, Michael; Andreas, Kolja; Engel, Ulf; Merklein, Marion (ASPEN/ASPE 2017 Spring Topical Meeting - Manufacture and Metrology of Structured and Freeform Surfaces for Functional Applications, 2017)
LFT Import::2019-08-05 (2225)

Analysis of stress pins for the local prestressing of cold forging tools - Killmann, Martin; Merklein, Marion (Production Engineering, 2021)
The trend towards lightweight design leads to an increasing demand for sophisticated part geometries with high functional integration. In order to use the advantages of cold forging regarding the time- and resource-efficient production of high-quality parts, high local stresses causing fatigue failure in geometrically complex tools have to be controlled. The objective of this manuscript is to analyse the use of stress pins for a local influence on the stress state within forging, especially in non-circular symmetrical cold forging dies. For this purpose, a closed-die forging process for elliptical parts is designed and analysed regarding the die stresses. Distinct areas with local compressive and tensile stresses occur in the process. To counteract the tensile stresses critical for fatigue failure, the effect of stress pins pressed into the die creating a local prestress is analysed. Around the pins, compressive radial and tensile tangential stresses occur. While large pin diameters, interferences and close positioning to the tensile area lead to an increasing prestressing effect, too high values of these parameters cause a detrimental superposition of tensile process and pin stresses. If used correctly, there is high potential to improve the stress state and tool life especially for locally stressed complex tools.<br
Keywords: Cold forging; Die design; Tool load; Local prestressing; Stress pins

Analysis of the bending effects and the biaxial pre-straining in sheet metal stretch forming processes for the determination of the forming limits - Affronti, Emanuela; Merklein, Marion (International Journal of Mechanical Sciences, 2018)
LFT Import::2019-07-29 (2291)
Keywords: Bending effect; Biaxial pre-straining; Forming limit curve; Sheet metal forming

Analysis of the binding mechanisms depending on versatile process variants of self-piercing riveting - Lüder, Stephan; Holtkamp, Pia; Wituschek, Simon; Bobbert, Mathias; Meschut, Gerson; Lechner, Michael; Schmale, Hans C. (Materials Research Proceedings 52, 2025)
The constantly increasing demand for climate protection and resource conservation requires innovative and versatile joining processes that improve adaptability to the joining task and robustness to enable flexible manufacturing on a production line. Therefore, the versatile SPR (V-SPR) and tumbling SPR (T-SPR) were developed. Using the example of a mixed material combination HCT590X+Z (t0 = 1.0 mm) / EN AW-6014 T4 (t0 = 2.0 mm), these processes were examined and compared with regard to the binding mechanisms form closure and force closure using micrographs, non-destructive resistance measurements and destructive torsion tests. For this purpose, a new sample geometry was defined, and the methods were adapted to the SPR process variant
Keywords: Joining; Sheet Metal; Self-Piercing Riveting

Analysis of the deformation behavior of Ti-6Al-4V at elevated temperatures - Merklein, Marion; Hagenah, Hinnerk; Kaupper, Markus; Schaub, Adam (Key Engineering Materials, 2013)
Titanium alloys, such as Ti-6Al-4V, offer favorable characteristics as significant strength, biocompatibility and metallurgical stability at elevated temperatures. These advantages afford the application of parts out of Ti-6Al-4V in a wide field within aerospace, astronautic and medical technologies. Most applied shaping operations for parts out of titanium alloys are forging, casting, forming and machining. In order to develop and improve forming operations numerical simulations are applied during preprocessing. For that purpose mechanical properties of the material such as yield stress and Lankford parameter have to be determined. Due to the two-phase (α + β) microstructure of Ti-6Al-4V, forming operations have to be carried out at elevated temperatures to reduce the required forming force and extend forming limits. Taking the temperature and stress state dependency of the material into consideration, uniaxial tensile and compression tests are accomplished at elevated temperatures, ranging from 400 to 600 °C. Furthermore, the experimenttally determined yield stress and Lankford parameter are approximated with the yield loci model proposed by Barlat 2000. The model predicts the flow response of the material, thus provides input data for the finite element analysis of forming processes at different temperature levels. Copyright © 2013 Trans Tech Publications Ltd.
LFT Import::2019-07-29 (1876)
Keywords: Compression test; Temperature effects; Tensile test; Ti-6AL-4V alloy; Yield loci

Analysis of the evolution of the Lankford coefficient in uniaxial tensile tests and validation with grain structure analysis - Lenzen, Matthias; Merklein, Marion (Proceedings of the Institution of Mechanical Engineers, Part B: Journal of Engineering Manufacture, 2022)
Modern materials mostly exhibit a low formability or a complex material behavior. For example, the common mild steel DC06 exhibits a strain state dependency in the yield stress and a strain dependency of the Lankford coefficients. Thus it is necessary to characterize the material properties from the onset of plastic deformation up to fracture. For example in the uniaxial tensile test, the flow stress and the r-values can be determined. According to the standards, the characterization is only applicable up to uniform elongation. In the case of DC06, the uniform elongation is with 24% comparatively low in contrast to the ultimate elongation with 60%. Research has proven, that the true stress can be characterized up to high strain in the uniaxial tensile test. For the strain dependent Lankford coefficient, this validation is missing. The aim in this investigation is the analysis of the strain dependent anisotropy up to high strain levels in uniaxial tensile tests and the validation. This is done with a comparison of optically measured r-values with the grain structure evolution of the pre stretched parts. These results prove the applicability of the standardized evaluation of Lankford coefficients out of DIC data above the uniform elongation.
CRIS-Team WoS Importer:2022-09-16

Analysis of the formation of gap-based leakages in polymer-metal electronic systems with labyrinth seals - Kleffel, Tobias; Frey, Philipp; Merklein, Marion; Drummer, Dietmar (Journal of Polymer Engineering, 2019)

Analysis of the influence of a cold leveling process on the properties of multi-layered aluminum sheets - Zettl, Bastian; Merklein, Marion (XLI. Verformungskundliches Kolloquium, 2023)
One approach for reducing emissions in the transportation and traffic sector is offered by lightweight material construction. In the automotive and aircraft industry, materials with a high specific strength are used, such as aluminum alloys of the 5xxx, 6xxx and 7xxx series. The strength of these alloys can be further increased by mechanical forming processes and the associated work hardening. The mechanical process group includes the so-called severe plastic deformation processes, which, by introducing very high degrees of plastic deformation, also induce the mechanism of fine-grain hardening in addition to work hardening. Accumulative roll bonding (ARB) is a process variant in which large-area semi-finished sheet products with a multilayered structure can be produced. It has already been identified that the layer interfaces and the intermediate bond strengths have a significant influence on the subsequent product properties, since delamination effects lead to premature material failure. For improving the dimensional accuracy and flatness of large-scaled sheets, straightening processes can be used. In this work, the influence of sheet leveling at room temperature on the feasibility and interface properties of ARB-products is investigated. In detail, the investigations include the analysis of the interface as well as the distribution of the sheet thickness as a function of the number of ARB process cycles in the initial state and after straightening at room temperature.<br
Keywords: accumulative roll bonding; cold leveling; multi-layered sheets

Analysis of the Influence of Surface Modifications on the Fatigue Behavior of Hot Work Tool Steel Components - Wild, Thomas; Platt, Timo; Biermann, Dirk; Merklein, Marion (Materials, 2021)
Hot work tool steels (HWS) are widely used for high performance components as dies and molds in hot forging processes, where extreme process-related mechanical and thermal loads limit tool life. With the functionalizing and modification of tool surfaces with tailored surfaces, a promising approach is given to provide material flow control resulting in the efficient die filling of cavities while reducing the process forces. In terms of fatigue properties, the influence of surface modifications on surface integrity is insufficiently studied. Therefore, the potential of the machining processes of high-feed milling, micromilling and grinding with regard to the implications on the fatigue strength of components made of HWS (AISI H11) hardened to 50 ± 1 HRC was investigated. For this purpose, the machined surfaces were characterized in terms of surface topography and residual stress state to determine the surface integrity. In order to analyze the resulting fatigue behavior as a result of the machining processes, a rotating bending test was performed. The fracture surfaces were investigated using fractographic analysis to define the initiation area and to identify the source of failure. The investigations showed a significant influence of the machining-induced surface integrity and, in particular, the induced residual stress state on the fatigue properties of components made of HWS.
Keywords: fatigue; surface modification; micromilling; high-feed milling; grinding; residual stresses; AISI H11

Analysis of the Lankford Coefficient Evolution at Different Strain Rates for AA6016-T4, DP800 and DC06 - Lenzen, Matthias; Merklein, Marion (AIP Conference Proceedings 1896(2017)160001, 2017)
None
LFT Import::2019-08-05 (2248)

Analysis of the modification of tool surfaces by abrasive blasting and laser polishing - Wild, Thomas; Bestenlehrer, Marcel; Merklein, Marion (Defect and Diffusion Forum, 2020)
The surface treatment of tools plays an important role for the operational behaviour of forming processes. Up to now, industrial standard is the manual finishing of tool surfaces, which can lead to a varying quality of the surface finish and therefore influence the tool service life and the forming results. One method to perform the polishing operation automatically is to remelt the top layer of materials by laser polishing. This is accompanied by a considerable change in the material properties in this zone. Therefore, the effect of laser polishing with respect to the local modification of the tool surface is investigated in this study. The results of the investigations reveal that a precise adjustment of the laser parameters is required in order to reduce the roughness of the surface. The heat input also leads to a significant influence on the microstructure of the material. In this study laser polishing remelts the material up to a depth of approximately 20 µm. Furthermore, it can be observed that the heat input during the process results in a heat affected zone of up to a depth of 30 µm. As a contrast to laser polishing, abrasive blasting is investigated as a roughness increasing surface modification.
CRIS-Team Scopus Importer:2020-12-04
Keywords: Laser; Polishing; Surface Modification

Analysis of the Part Quality and Process Stability when Producing Metallic Micro Parts by Multi-Stage Bulk Forming from Sheet Metal - Kraus, Martin; Merklein, Marion (Key Engineering Materials, 2022)
Miniaturization of parts for technical products is an ongoing trend across all industries over the past decades. Due to the large number of possible applications, several billion micro parts are produced every year. In mass production, cold forming offers technological, economical and ecological benefits in comparison to other manufacturing methods. Unfortunately, due to size effects that negatively influence the part geometry, the process stability, the handling and the tool stress, this manufacturing technology is currently barely used. Previous research results have shown that bulk microforming from sheet metal has the potential to reduce the aforementioned restrictions decisively. Within this paper, a three-stage bulk microforming process from sheet metal is experimentally analysed to form a demonstrator geometry with dimensions in the sub-millimetre range in all spatial directions. In the first stage, material is provided in form of a pin for subsequent forming stages. During the second stage, a cup geometry is formed on the pin. Finally, the micro part is separated from the sheet metal by shear cutting. To ensure a wide range of applications, the investigations are carried out with copper, steel and aluminium material. This study is focused on the evaluation of the achievable part quality and the process stability. For the evaluation of the geometry and the surface quality, the micro parts are optically measured with a three-dimensional surface measuring system. The standard deviation of the part dimensions and the process forces are used to investigate the influence of size effects in relation to the material and the grain structure.
CRIS-Team Scopus Importer:2022-11-04
Keywords: Bulk microforming; Metallic micro parts; Pin extrusion; Sheet metal; Size effects

Analysis of the stress and directional dependent Bauschinger-effect of sheet metals - Rosenschon, Martin; Merklein, Marion (IOP Conference Series: Materials Science and Engineering, 2018)
The increasing application of lightweight metals in combination with a growth in the complexity of components provides new challenges to the numerical modeling of sheet materials. The choice of the material model and the associated mapping of the hardening behavior are of substantial importance for a realistic process prediction and the following spring back calculation in particular. The implementation of the Bauschinger-effect via isotropic-kinematic hardening laws can lead to a substantial improvement of the prediction quality. It is commonly known, that an accurate prognosis of sheet metal forming processes requires the consideration of the semi-finished products anisotropy. However, the identification of the Bauschinger-effect, which describes the reduction of the yield stress after a load reversal, and corresponding numerical models, is usually done under a specific stress state and in one direction of the sheet. Considering the vast variety of stress states and loading directions occurring in a forming operation, the anisotropic behavior of the Bauschinger-effect under uniaxial stress and its evolution during shearing is analyzed. Using a miniaturized tension-compression test, the cyclic hardening of the mild steel DX56 and the high strength steel DP600 and the aluminum alloy AA6016 is characterized in 0°, 45° and 90° to the rolling direction. By the identification of an isotropic-kinematic hardening law in combination with the anisotropic flow criterion Yld2000-2d the model's ability to extrapolate the hardening behavior is evaluated. In the last step, the transferability of parameters from the uniaxial stress state to results from a modified shear test is analyzed.
CRIS-Team Scopus Importer:2023-03-29

Analysis of the stress state in non-axially symmetrical cold forging dies - Killmann, Martin; Merklein, Marion (Procedia Manufacturing, 2020)
Conventionally, reinforcement systems are used to decrease tensile stresses in axially symmetrical cold forging dies. The increasing complexity of parts due to lightweight design leading to higher functional integration causes the necessity of producing non-axially symmetrical parts, for which there is insufficient knowledge about the adequate application of reinforcement systems. To gain understanding about the stress distribution for non-axially symmetrical dies, a cold forging process for producing elliptical parts is introduced and numerically described. The simulation model is validated in a test set up with strain gauges, which are used to measure the strains on the die and reinforcement ring. Subsequently, the process is analysed regarding the location, direction and magnitude of the resulting prestresses and maximum stresses. Based on the findings, a classification of areas for non-circular symmetrical cold forging tools is introduced. The compressive area is subjected to increasingly high contact pressures by the workpiece. This leads to compressive radial stresses and radial displacements. The high displacements induce a bending effect, which causes tangential stresses in the tensile area. The gained process understanding is used to propose measures for improving the stress state in cold forging dies for asymmetrical parts by locally strengthening the reinforcement syste
Keywords: Cold Forming; Forging; Die Load; Asymmetrical Tools; Reinforcement Systems

Analysis of the thermomechanical flow behavior of carburized sheet metal in hot stamping - Horn, Alexander; Merklein, Marion (Forming the Future - Proceedings of the 13th International Conference on the Technology of Plasticity, 2021)
The reduction of fuel consumption due to restrictions regarding CO2 emissions is one of the major driving forces for lightweight design in the automotive industry. In this context, hot stamping of ultra-high-strength steels has developed to a state of the art process for manufacturing safety-relevant components. With regard to passenger safety and weight reduction, further potential lies in the functional optimization of the parts. Prior local carburization followed by hot-stamping is a new process variant for tailored properties, which overcomes the limitations of established processes. Due to the varying carbon content after carburization, the sheets have graded mechanical properties. Within this contribution, the influence of temperature, strain rate and carburization on the flow behavior will be investigated. For this purpose, tensile tests at elevated temperatures are carried out in a physical simulator of type Gleeble. The resulting flow curves of the carburized complex phase steel are modeled with a modified Norton-Hoff hardening law and the influence of the carburization process is analyzed by means of the initial yield stress. Furthermore, the results from tensile tests are correlated with the phase transformation behavior obtained by a laser ultrasonic sensor.
CRIS-Team Scopus Importer:2021-09-03
Keywords: Carburization; Hot stamping; Quenching

Analysis of the Young’s modulus reduction and cyclic hardening of HCT780X - Rosenschon, Martin; Merklein, Marion (Proc. of MATFEM Conference 2017, 2017)
LFT Import::2019-08-05 (2272)

Analysis of tool-sided surface modifications for dry deep drawing of deep drawing steel and aluminum alloys in a model process - Steiner, Jennifer; Häfner, Tom; Zhao, Rong; Andreas, Kolja; Schmidt, Michael; Tremmel, Stephan; Merklein, Marion (Dry Metal Forming Open Access Journal, 2017)
The concept of sustainability motivates the development of energy-saving and low-polluting production processes. A sheet metal forming process without usage of lubricants is considered as one of these green production technologies. Forming processes without the need for traditional lubricants save process steps and additional costs to remove the remaining lubrication from the workpiece after forming. In order to realize such a dry forming process and to adjust the material flow effectively, tool surfaces were modified by amorphous carbon coatings and different surface finishing processes for roughness adjustment. To verify the general feasibility of the lubricant-free metal forming process, deep drawing of rectangular cups with and without lubrication with conventional forming tools was investigated. The dry deep drawing process was modelled numerically to analyze process parameters and identify critical contact conditions. By strip drawing tests, the tribological behavior of ta-C and a-C:H coated tools with different surface treatments was investigated. The deposition process and resulting properties of a-C:H coatings were further analyzed to improve their tribological performance. The effects of the process parameters – deposition temperature and bias voltage in the deposition chamber – were investigated using the one-factor-at-a-time method. The strip drawing tests revealed a high influence of the surface roughness of coated tools on the tribological behavior. Therefore, laser based smoothing was further investigated in this study. Laser radiation at 355 nm wavelength was applied as an effective and minimum heat-generating technique to remove the roughness asperities on ta-C coatings which are built during its growth. Finally, ta-C and a-C:H coatings were applied on tool surfaces and tested in a drawing process of strip profiles. As reference the same forming process with a conventional forming tool was carried out.<br
Keywords: Dry Deep Drawing; Tribology; Carbon Based Coatings; Laser Based Modification

Analysis of tribological behavior of surface modifications for a dry deep drawing process - Henneberg, Johannes; Rothammer, Benedict; Zhao, Rong; Vorndran, Martin; Tenner, Jennifer; Krachenfels, Kim; Häfner, Tom; Tremmel, Stephan; Schmidt, Michael; Merklein, Marion (Dry Metal Forming Open Access Journal, 2019)
The global trend towards more environment-friendly and sustainable production motivates the development of efficient manufacturing processes. Forming technology has great potential regarding that due to its high material efficiency. Research is necessary to improve the sustainability of established forming processes such as deep drawing. One possibility to improve the environmental friendliness of deep drawing is the realization of lubricant-free processes. This avoids the usage of harmful lubricants. Additionally, it has the potential to shorten process chains by eliminating cleaning steps. However, dry deep drawing is associated with challenges. Due to the lack of a lubricant between tool and workpiece, friction and wear increase. An approach to overcome these challenges is the usage of modified tool surfaces. In this context, the aim of this research is to investigate dry deep drawing operations under application-oriented conditions. Firstly, the cause-effect relationships between the properties and tribological performance for a-C:H and ta-C coating systems as well as laserbased micro-textures are investigated in strip drawing tests using the workpiece materials DC04 and AA5182. Therefore, different amorphous carbon coating approaches for DC04 and AA5182 are evaluated. Beside of coatings, diverse laser micro-texturings are investigated and applied on forming tools. Key parameters are identified, which result in low friction and adhesion. Based on these findings, the different modifications are evaluated. Promising modifications are selected and applied in a novel test rig under application-oriented conditions to analyze their durability. The test rig enables the time- and material-efficient forming of a great number of parts. In this regard, in addition to the occurring process forces, the tool and component topographies are determined at periodic intervals in order to derive the cause-effect relationships between friction, wear and component quality as well as to demonstrate the feasibility of dry deep drawing operations under application-oriented forming conditions.<br
Keywords: Dry Deep Drawing; Tribology; Carbon Based Coatings; Laser Based Modification

Analysis of Varying Properties of Semi-finished Products in Sheet-bulk Metal Forming of Functional Components - Schneider, Thomas; Vierzigmann, Ulrich; Merklein, Marion (AIP Conference Proceedings, 2014)
LFT Import::2019-07-29 (1915)

Analysis of Work Hardening and Tribological Changes After a Gap Controlled Drawbead Passage - Schmid, Harald; Merklein, Marion (The Minerals, Metals & Materials Series. Springer, Cham., 2021)

Analytical and numerical approaches to predict the flow characteristics of a magnetorheological fluid in rotational symmetric cross sections - Rösel, Sebastian; Merklein, Marion; Grüner, Martin (Key Engineering Materials, 2012)
For a better understanding of the hydroforming process using magnetorheological fluids as a medium it is necessary to gain basic information for an analytical and numerical description of the fluid behaviour under process relevant conditions. Therefore an experimental setup is build up, which consists of a pressure chamber and a rotational symmetric outlet. Different parameters like feed rate and magnetic flux density are varied. Afterwards an analytical approach and a numerical model are developed. To get the relevant material input data for the fluid description an additional numerical simulation of the created magnetic flux density with flux lines perpendicular to the symmetry line of the outlet is performed. The leakage rates, which are observed for the experiments, are compared to the analytically calculated ones and to the results of the numerical simulation. © (2012) Trans Tech Publications.
LFT Import::2019-07-29 (1803)
Keywords: Active fluid media; Hydroforming; Magnetorheological fluid (MR-Fluid); Sheet metal forming

Analytical friction force compensation of flow curves out of layer compression tests with the pin extrusion test - Lenzen, Matthias; Kraus, Martin; Merklein, Marion (International Journal of Material Forming, 2020)
For conventional material models like Yld2000-2d or BBC05 the equi-biaxial yield strength is required for the parameter identification. In this context, a commonly used test setup is the hydraulic bulge test. However, an inaccuracy in the characterization of the initial yield strength is present in the hydraulic bulge test. Due to the evaluation of the resulting curvature of the specimen, that is nearly infinite at the onset of yielding, the calculated stress can significant vary. Another proposed test setup for the characterization of the equi-biaxial stress state is the layer compression test. Here, the onset of yielding can be characterized with sufficient accuracy. The disadvantage in this test is the friction between stack and tool that leads to an overestimation of the flow curve. Thus, robust and experimental based friction compensation should be used, to gain a comparable hardening behaviour as in the hydraulic bulge test. In this contribution, the friction in the layer compression test is compensated by characterization of the tribological conditions. Thus, the tribological system consisting of workpiece surface, tool surface and lubricant is characterized using pin extrusion tests. The friction is analysed for the two steel grades DC06 and DP600 and the aluminium AA5182. With the identified friction factors, the measured testing force in the layer compression test is reduced by the portion of friction. For verification, hydraulic bulge tests, which are approximately friction free, are performed and compared with the resulting flow curves of the layer compression tests. Results confirm, that a friction compensation of the layer compression tests lead to a significant improvement of the resulting material parameters in comparison to the hydraulic bulge tests. Additional, a new method for the friction factor characterization is presented that uses in the stress difference of flow curves characterized in hydraulic bulge tests and layer compression tests.
CRIS-Team Scopus Importer:2020-05-12
Keywords: Friction compensation; Layer compression test; Material characterization; Pin extrusion test

Analytical studies on laser cut surfaces - Biermann, Stefan; Nuss, Rudolf; Geiger, Manfred (Proceedings of the 7th International GCL-Symposium, Vienna, Austria, 1988)
LFT Import::2019-08-05 (266)

Analytic Methods for the Calculation of the Heat Transfer Coefficient - Merklein, Marion; Wieland, Michael; Stöhr, Thomas; Lechler, Jürgen; Grüner, Martin (International Review of Mechanical Engineering, 2010)
In the product development cycle numerical simulations are commonly used for the process layout. In case of hot stamping the process layout gets quite complex because material's thermal and mechanical properties have to be taken into account. Hot stamping can be explained as forming and quenching in one process step and therefore the knowledge of thermal properties is indispensable to fulfill the opposing requirements of a good heat flux with respect to a good energy balance of the tool. A description of this energy exchange between the hot blank and the tool is given by the heat transfer coefficient. The determination of the heat flux under process relevant conditions for hot stamping is influenced by several variables. Within the scope of this work, these different variables are compared using two analytical methods to calculate the heat transfer coefficient based on the same measurement data. Furthermore the advantage of these analytical methods and the possibility of improvement is shown up. At least a validation of the calculated heat transfer coefficients by simulation is presented. Copyright © 2010 Praise Worthy Prize S.r.l. - All rights reserved.
LFT Import::2019-07-29 (224)
Keywords: Heat transfer coefficient; Hot stamping

Analytisches Modell für das Laserstrahlbiegen von Profilen - Geiger, Manfred; Kraus, Jürgen; Pohl, Thomas; Hoffmann, Peter; Vollertsen, Frank (Laser-Magazin, 1994)
LFT Import::2019-07-15 (595)

An approach for a metamodel-based consideration of a process chain when mechanically joining sheet metal components - Neumann, Jonas; Kappis, Lukas; Lontsi, Seraphin Tsi-Nda; Ludwig, Jean-Patrick; Ramaiya, Umang Bharatkumar; Scharr, Christian; Vallaster, Eva; Flügge, Wilko; Meschut, Gerson; Merklein, Marion (15th Forming Technology Forum, 2024)
Batch and process fluctuations during the fabrication of sheet metal components result in discrepancies in the resulting component properties, affecting subsequent process steps and potentially leading to production rejects. Consequently, the identification of deviations and knowledge of the effects of fluctuations are crucial for achieving consistently high product quality, reducing waste and thus increasing resource efficiency of production processes through countermeasures derived from this. The approach presented to address this is the use of data-driven metamodeling to map entire process chains and predict process parameters in order to compensate for process and batch fluctuation. The investigated process chain consists of the sub-processes deep drawing, clamping and clinching. For each process step, relevant input and output variables are identified, numerical simulation models are created, and subsequently validated. Variant simulations of the sub-processes are conducted and evaluated to generate a database for the metamodeling of the individual process steps. Machine learning techniques are utilized for the automated selection and optimization of learning methods to create models that depict the relationships between input and output variables. Finally, the models for the sub-processes are linked together to form a superordinate metamodel for the entire process chain, with the aim to make inline-process adaptations possible.<br

An Approach to a Process Model of Laser Beam Melt Ablation Using Methods of Linear and Non-linear Data Analysis - Donner, R.; Cser, Adrienn Orsolya; Schwarz, U.; Otto, Andreas; Feudel, U. (Proceedings of the 4th International Symposium on Investigations of Non-Linear Dynamic Effects on Production Systems, Chemnitz, April 8-9, 2003)
LFT Import::2019-08-05 (937)

A new approach for the determination of the linear elastic modulus from uniaxial tensile tests of sheet metals - Suttner, Sebastian; Merklein, Marion (Journal of Materials Processing Technology, 2017)
The determination of the linear elastic modulus is important for the numerical process design of forming operations. Test setups for the identification of the linear elastic modulus can be divided into dynamic methods like ultrasonic measurement and static methods like indentation tests or uniaxial tensile tests. Relevant standards recommend the determination of the linear elastic modulus via linear regression from stress vs. strain curves, while no information for an upper boundary exists. In this contribution, a new approach is presented, which uses the deformation work to identify a material-dependent upper boundary for the determination of the linear elastic modulus. The method is applied to two aluminum alloys AA5182-O and AA6016-T4, a deep drawing steel DX54, two advanced high strength steels HCT600X and HCT980X and a magnesium alloy AZ31B. The results confirmed a robust determination of the linear elastic modulus from the linear elastic behavior and a good reproducibility with a deviation below 5%. Moreover, with exception of AA5182-O, all investigated materials exhibit a quasi-elastic-plastic (QPE) transition between elastic and plastic material behavior.
LFT Import::2019-07-29 (2200)
Keywords: Elasticity; Material characterization; Young's modulus

A new approach to the evaluation of forming limits in sheet metal forming - Merklein, Marion; Maier, Andreas; Kinnstätter, Daniel; Jaremenko, Christian; Affronti, Emanuela (Key Engineering Materials, 2015)
UnivIS-Import:2015-04-14:Pub.2015.tech.IMMD.IMMD5.anewap

A new process chain for joining sheet metal to fibre composite sheets - Plettke, Raoul; Schaub, Adam; Gröschel, Christian; Scheitler, Christian Josef; Heinle, Martina; Ranft, Florian; Merklein, Marion; Schmidt, Michael; Drummer, Dietmar (Key Engineering Materials (Volumes 611 - 612), 2014)
Mixed-Materials parts have great light-weight potential for the automotive application to reduce the carbon footprint. But the joining of fibre composite plastic sheets to metal sheets is in practical application limited to adhesive bonding or mechanical joining with additional fastener elements due to the large differences in physical properties. A new process chain based on plastic joining without fastener elements is proposed and first results on the mechanism and on the achievable strength of the new joints are shown. The process chain consists of three steps: First joining pins are added to the sheet metal by an additive manufacturing process. In a second step these pins are pierced through the fibre composite sheet with a local heating of the thermoplastic in an overlap setup. In the third and last step the joint is created by forming the pins with the upsetting process to create a shape lock. The shear strength of the joined specimens was tested in a tensile testing machine. The paper shows that even with a non-optimized initial setup joints can be realised and that the new process chain is a possible alternative to adhesive bonding. © 2014 Trans Tech Publications, Switzerland.
UnivIS-Import:2018-09-06:Pub.2014.tech.FT.FT-KT.anewpr
Keywords: Aluminium; Endless-fibre reinforced plastics; Joining; Joining by forming; Mixed materials; Titanium

A new process chain for joining sheet metal to fibre composite sheets - Plettke, Raoul; Schaub, Adam; Gröschel, Christian; Scheitler, Christian Josef; Vetter, Martina; Hentschel, Oliver; Ranft, Florian; Merklein, Marion; Schmidt, Michael; Drummer, Dietmar (Key Engineering Materials, 2014)
Keywords: Aluminium; Endless-fibre reinforced plastics; Joining; Joining by forming; Mixed materials; Titanium

A new production process for soft actuators and sensors based on dielectric elastomers intended for safe human robot interaction - Reitelshöfer, Sebastian; Landgraf, Maximilian; Gräf, Daniel; Bugert, Larissa; Franke, Jörg (2015 IEEE/SICE International Symposium on System Integration (SII), 2015)
Dielectric elastomers are the subject of intense research in material science. A large number of publications describe artificial muscles based on dielectric elastomer actuators as a promising alternative for an energy efficient, lightweight and flexible actuation architecture. Dielectric elastomer actuators could improve and extend the capabilities of robots in terms of soft kinematics for the direct physical interaction between humans and robots. They could also improve the dynamical performance and the eligibility for energy autarkic operation of robotic systems. Another field of application are dielectric elastomer sensors that can bear and detect large deformation. However, up to now dielectric elastomer actuators and sensors are not available on a large scale with reproducible characteristics. The focus of this contribution lies on a new automated production process using Aerosol-Jet-Printing for dielectric elastomer actuators and sensors with very favorable characteristics resulting from the additive manufacturing aiming at an improved availability of such sensors and actuators.
Keywords: deformation; electroactive polymer actuators; human-robot interaction; industrial robots; rapid prototyping (industrial); three-dimensional printing; additive manufacturing; aerosol-jet-printing; artificial muscles; automated production process; deformation detection; dielectric elastomer actuators; dielectric elastomer sensors; energy autarkic operation; energy efficient lightweight flexible actuation architecture; human-robot physical interaction; robot kinematics; robotic systems; soft actuators; soft sensors; Actuators; Dielectrics; Printing; Sensor phenomena and characterization; Service robots

A new strategy for manufacturing tailored blanks by a flexible rolling process - Hildenbrand, Philipp; Lechner, Michael; Merklein, Marion (Materials Science Forum, 2016)
LFT Import::2019-07-29 (2143)
Keywords: Forming; Rolling; Sheet metal

A New Way for the Adaption of Inverse Identified GTN-Parameters to Bending Processes - Tsoupis, Ioannis; Merklein, Marion (13th International LS-DYNA Users Conference 2014, 2014)
LFT Import::2019-08-05 (2023)

An Experimental Analysis of the Onset of Buckling in Sheet Metal Forming - Sobis, Tomasz; Engel, Ulf; Geiger, Manfred (International Journal of Materials & Product Technology, 1992)
In this study a test method is presented in which buckling phenomena can be investigated at a fundamental level. A rectangular sheet sample is fixed in a specially designed mounting device which transfers tensile forces in the longitudinal direction as well as compressive forces in the perpendicular direction. The mechanical principle used ensures a steady ratio of the corresponding strains. Onset and growth of the wrinkle can be monitored by special measuring equipment. The aim of the experimental and theoretical investigations described in this paper was to check the operational characteristics and capabilities of the equipment and to deduce a reproducible criterion for the formation of wrinkles.
LFT Import::2019-07-15 (487)

An experimental and numerical investigation of different shear test configurations for sheet metal characterization - Yin, Qing; Zillmann, Benjamin; Suttner, Sebastian; Gerstein, Gregory; Biasutti, Manfredi; Tekkaya, A. Erman; Wagner, Martin F. -X.; Merklein, Marion; Schaper, Mirko; Halle, Thorsten; Brosius, Alexander (International Journal of Solids and Structures, 2014)
Simple shear tests are widely used for material characterization especially for sheet metals to achieve large deformations without plastic instability. This work describes three different shear tests for sheet metals in order to enhance the knowledge of the material behavior under shear conditions. The test setups are different in terms of the specimen geometry and the fixtures. A shear test setup as proposed by Miyauchi, according to the ASTM standard sample, as well as an in-plane torsion test are compared in this study. A detailed analysis of the experimental strain distribution measured by digital image correlation is discussed for each test. Finite element simulations are carried out to evaluate the effect of specimen geometries on the stress distributions in the shear zones. The experimental macroscopic flow stress vs. strain behavior shows no significant influence of the specimen geometry when similar strain measurements and evaluation schemes are used. Minor differences in terms of the stress distribution in the shear zone can be detected in the numerical results. This work attempts to give a unique overview and a detailed study of the most commonly used shear tests for sheet metal characterization. It also provides information on the applicability of each test for the observation of the material behavior under shear stress with a view to material modeling for finite element simulations. © 2013 Elsevier Ltd. All rights reserved.
LFT Import::2019-07-29 (1932)
Keywords: Heterogeneity; Sheet metal; Simple shear

An Experimental Study of the Onset of Buckling in Sheet Metal Forming - Geiger, Manfred; Engel, Ulf; Otto, Andreas (Int. J. Mater Product Technol. Nr. 7/3, 1991)
LFT Import::2019-08-05 (354)

An improvement of the time dependent method based on the coefficient of correlation for the determination of the forming limit curve - Merklein, Marion; Kuppert, Andreas; Affronti, Emanuela (Advanced Materials Research, 2014)
Due to the global energy policy according to the aims of economic efficiency and environmental compatibility the production of lightweight constructions is nowadays a need in many fields of mechanical engineering, especially in automotive and aerospace sectors. The substitution of conventional deep drawing steels with modern sheet metals, i.e. aluminium or high strength steel, provides a positive contribution towards this trend. Prerequisite for an efficient application of these resources is a comprehensive material characterization including the analysis of the formability as well as the failure behaviour. Regarding the accurate prediction of forming behaviour, a robust failure criterion is necessary in order to perform the numerical simulation designs by using finite element method (FEM). The leading criterion used for sheet metal forming is the forming limit diagram (FLD). The FLD gives a graphical description of material formability by plotting the major strain values related to the minor strain values to failure in a curve called forming limit curve (FLC). With the improvement of the digital image correlation (DIC) techniques, which provide very accurate strain measurement, new methods relied on the strain history of the specimen during the test are proposed to determine the FLC. Within this paper, the time dependent method based on the coefficient of correlation is investigated. In particular an improvement dependent on experimental parameter is presented in order to increase its sensibility and reliability for different materials.
LFT Import::2019-08-05 (2037)
Keywords: Forming limit curve (FLC); Metal forming; Sheet metal

An incremental analysis of a deep drawing steel’s material behaviour undergoing the predeformation using drawbeads - Schmid, Harald; Suttner, Sebastian; Merklein, Marion (IOP Conf. Series: Journal of Physics: Conf. Series 896 (2017) 011001, 2017)
LFT Import::2019-08-05 (2237)

An innovative approach for the process design for three-roll bending of plain tubular components - Cojutti, Massimo; Vipavc, Daniel; Hagenah, Hinnerk; Merklein, Marion (Proc. 1st Int. Congress on Roll Forming, 2009)
LFT Import::2019-08-05 (134)

An Innovative Process Combination of Additive Manufacturing and Sheet Bulk Metal Forming for Manufacturing a Functional Hybrid Part - Merklein, Marion; Schulte, Robert Karl; Papke, Thomas (Journal of Materials Processing Technology, 2020)
The combination of additive manufacturing (AM) and forming offers new opportunities in part and process chain design. To show the potential of this process combination, a gear component with discrete tooth geometry is manufactured by powder bed fusion of metal using a laser beam (PBF-LB/M) and forming. Such gear components are manufactured conventionally in a process chain of several sheet bulk metal forming operations like orbital forming, deep drawing and upsetting. Orbital forming is used to manufacture a tailored blank to increase form filling in the subsequent forming operations. However, challenges are form filling and control of material flow. These severely affect whether the target geometry can be realized. To overcome these limitations, in this work PBF-LB/M is used to manufacture the tooth geometry close to the target on a flat sheet. Subsequently, the three-dimensional part geometry is realized by forming. The advantage is that the orbital forming step is not necessary. With that, the tooth geometry does not depend on material flow. A further benefit is geometric flexibility of additive manufacturing processes. Hence, diversity of variations can be increased over a wide range without additional cost intensive forming tools for each single part geometry. Besides, the potentials and challenges of the approach are discussed. The investigations include characterization of formability of sheet metal and AM material, metallographic analysis and hardness measurement. A process chain for manufacturing hybrid parts is presented and the final part geometry is evaluated by topography measurement. The major finding is that the tooth geometry manufactured by additive manufacturing and forming is closer to the target than for the conventional process chain. Additionally, a comparison of technological and economic advantages is drawn. Finally, an extension of the approach is presented by hybrid parts with additively manufactured structures on both sides of the sheet metal.<br
Keywords: Forming; Additive manufacturing; Process combination; Hybrid part

An inverse approach to the numerical design of the process sequence of tailored heat treated blanks - Geiger, Manfred; Merklein, Marion; Staud, Detlev; Kaupper, Markus (Production Engineering, 2008)
While in industries lightweight construction gain an increasingly significant role and as weight reduction is often done with aluminum sheets, advanced production technologies have to be developed to be competitive for this evolution. Since steel sheet metal parts cannot be substituted directly with aluminum due to its minor formability, the usage of so called tailored heat treated blanks (THTB) is presented in this work. THTB are locally heat treated aluminum blanks from the 6,000-series alloy which exhibit a specific strength pattern optimized to the forming operation leading to a significantly improved formability for the manufacturing of complex aluminum car body parts. The enhancement of the formability is reached by a local heat treatment before the forming process. Due to the strong interdependency of heat treatment and forming operation, a numerical investigation of the process sequence is a prerequisite for a cost-effective usage of the THTB. An inverse approach on basis of a finite element simulation enables the determination of process parameters for an optimized THTB, thus having an effective and efficient engineering method for this technology. © German Academic Society for Production Engineering (WGP) 2007.
LFT Import::2019-07-29 (204)
Keywords: Aluminum; Production process; Simulation

An investigation into laser sintering of PEEK - Rechtenwald, T.; Niebling, Frank; Pohle, D.; Eßer, Gerd (LANE 2004, Proceedings of the 4th International Conference on Laser Assisted Net Shape Engineering, 2004)
LFT Import::2019-08-05 (1110)

Anlagen- und Prozeßdiagnostik an Bearbeitungssystemen mit Nd:YAG-Lasern - Geiger, Manfred; Gropp, Armin (Trennen mit Festkörperlasern, 1993)
LFT Import::2019-07-15 (397)

Anlagen- und Prozeßdiagnostik beim Schneiden mit einem gepulsten Nd:YAG-Laser - Gropp, Armin (Friedrich-Alexander-Universität Erlangen-Nürnberg, 1995)
The aim of this thesis has been to improve the process understanding for the manufacturing method cutting with pulsed Nd:YAG-lasers. To view this topic in its entirety diagnostic examination has been carried out in the entire working system and during the process. Optical signals emitted by the process have been registered by means of different detectors. The analysis of the signals shows that the interaction is usually connected with laser pulse duration. Therefore irregular courses of some signals can be used to monitor the process. Three dimensional cutting courses show that the extent of accuracy of the work piece is dominated by the guiding behavior of the robot. However, any influence of gravity on the process could not be found. The pulsed mode and the low mean power of the laser are advantageous when working on complex contours because of a low susceptibility of the process and with it the working quality with regard to a drop of the cutting speed below optimal value

A non-invasive form finding approach with application to metal forming - Landkammer, Philipp; Schneider, Thomas; Schulte, Robert Karl; Steinmann, Paul; Merklein, Marion (Production Engineering, 2016)
Inverse form finding aims in determining the optimal material configuration of a workpiece for a specific forming process. A gradient- and parameter-free (nodal-based) form finding approach has recently been developed, which can be coupled non-invasively as a black box to arbitrary finite element software. Additionally the algorithm is independent from the constitutive behavior. Consequently, the user has not to struggle with the underlying optimization theory behind. Benchmark tests showed already that the approach works robustly and efficiently. This contribution demonstrates that the optimization algorithm is also applicable to more sophisticated forming processes including orthotropic large strain plasticity, combined hardening and frictional contact. A cup deep drawing process with solid-shell elements and a combined deep drawing and upsetting process to form a functional component with external teeth are investigated.
LFT Import::2019-08-07 (2148)
Keywords: Inverse form finding; Shape optimization; Cup deep drawing; Sheet-bulk Metal Forming

A novel approach for high-precision blanking of thin metal foils using monocrystalline silicon as tool material - Hildering, Sven; Engel, Ulf (Proc. 7th Int. Conf. Multi-Material Micro Manufacture, 2010)
LFT Import::2019-08-05 (721)

A Novel Approach for In-Situ Observation of Local Deformation Behaviour at Micro Scale - Geißdörfer, Stefan; Engel, Ulf; Geiger, Manfred (Proceedings of the 9th International Conference on Technology of Plasticity, 2008)
Microforming processes are characterized by a significant influence of the microstructure on the deformation behaviour. While effects which are influencing the integral deformation behaviour like the influence of the free surface on the material properties are meanwhile identified and welldescribed, the local deformation behaviour of grains which has a significant impact on the final shape evolution is still not understood. In dependency of the grain size as well as the grain orientation, local deformation behaviour is yielding to differences in die filling and in shape evolution. Within this paper, a methodology is discussed to determine and analyze the local deformation behaviour by in-situ optical measurements of stress-strain state within the deformation area. Based on first investigations, a cold forging tool system has been developed in order to measure the local deformation within the specimen using can-backward extrusion process. The process layout is reduced to the deformation of a half cylinder where the die is closed by a sapphire window. Through this translucent tool the deformation process can be observed in-situ by a CCD-camera with a resolution of about two microns. The local deformation information of the captured images can be used for the calculation of the strain distribution. Based on this improved understanding of local deformation behaviour, previously described simulation models can be enhanced and finally verified.
LFT Import::2019-08-05 (1533)

A novel ultrasonic-assisted staking process for mechanical fasteners - Jäckisch, Manuel; Merklein, Marion (Proceedings of the Institution of Mechanical Engineers Part L-Journal of Materials-Design and Applications, 2022)
Increasing material variety in car body engineering causes new challenges regarding the joining processes and therefore, leads to an enhanced usage of mechanical joining technologies. Mechanical fasteners, as self-piercing nuts, can be staked cost-efficiently without a pre-punching operation to create detachable joints. Nevertheless, elevated workpiece strengths lead to high forming forces and a limited application range. One promising approach to reduce tool and workpiece loads in forming operations is superimposing a high-frequency oscillation to the tool movement. The so-called ultrasonic assistance enables an immediate and considerable reduction of the material’s flow stress. This beneficial softening effect has been confirmed for several materials and processes. Since the process management and monitoring are highly affected by the frequency-dependent dynamic behavior of the whole test setup, the application of ultrasonic assistance is already challenging for basic forming operations. Hence, only a few studies have been investigating ultrasonic-assisted joining processes. In particular, joining processes with auxiliary elements have been hardly considered. Within the scope of this work, a novel ultrasonic-assisted staking process for mechanical fasteners is proposed. Therefore, the punch movement for the installation of a self-piercing nut into an aluminum sheet is superimposed with a 20 kHz oscillation of 10 μm, 15 μm, and 20 μm amplitude. Ultrasonic assistance in the initial staking phase, characterized by moderate loads, causes irregular tool–specimen contact. Since the effect is promoted by increasing amplitudes, a correlation with the elastic tool deflection is presumed. Additionally, the transferability of the ultrasonic-based force reduction to mechanical joining with auxiliary element is confirmed and a beneficial influence on the joint formation is identified. Thus, ultrasonic assistance is proven as a promising approach for the extension of existing process limits.<br
Keywords: ultrasonic; joining; aluminum; measurement

Anrißerzeugung in WC Co Hartme¬tall Proben für die Messung des kritischen Spannungsintensitätsfaktors KIc. - Wissmeier, Hans-Jürgen; Engel, Ulf (Materialwissenschaft und Werkstofftechnik, 1989)
LFT Import::2019-07-16 (1959)

Anwendungsorientiertes Laserstrahlumformen - Merklein, Marion; Hennige, Thomas (Idee-Vision-Innovation, 2001)
LFT Import::2019-07-15 (897)

Anwendung von CCD-Kameras für digitale Bildverarbeitung: Synchronisation, Auflösungsvermögen und Fehlerquellen - Heckel, Werner (Proceedings SENSOR 93, Nürnberg, Oktober, 1993)
LFT Import::2019-08-05 (451)

Apllication of fuzzy logic for process design in sheet metal hydroforming - Hagenah, Hinnerk; Kohlbauer, Rainer (Proceedings of the 9th CIRP International Workshop on Modeling of Machining Operations, 2006)
LFT Import::2019-08-05 (1262)

Applicability of a magnetorheological fluid to the flow influenced hydroforming process - Dal Bò, Paolo; Geiger, Manfred (Proceedings of the 9th ESAFORM Conference on Material Forming, 2006)
LFT Import::2019-08-05 (1348)

Applicability of blasted blanks for adaption of tribological conditions in sheet-bulk metal forming - Löffler, Maria; Andreas, Kolja; Engel, Ulf; Merklein, Marion (Procedia CIRP, 2016)
LFT Import::2019-07-29 (2159)
Keywords: Sheet-bulk metal forming; Surface modification; Tribology

Applicability of Solid Lubricant Coatings in Cold Rod Extrusion of Stainless Steels - Jobst, Andreas; Merklein, Marion (Defect and Diffusion Forum, 2020)
Cold extrusion is an established technology for the production of dimensionally accurate components in large series. Due to the high material and energy efficiency, a resource-saving manufacturing of high-performance parts is possible. Forming at room temperature leads to an advantageous grain structure and work hardening of the material, resulting in components with favorable operating characteristics. Nevertheless, a challenge is the generation of residual stresses during forming, which are influencing the fatigue behavior. The modification of the tribological conditions is one method for influencing the parts’ residual stress state. However, the high strength and work hardening of the materials formed at room temperature leads to high tribological loads between billet and die. These challenges are intensified by the increasing use of stainless steels due to growing demands for corrosion resistant components. The aim followed within this paper is therefore to investigate the applicability of typical lubricant coatings in the forward rod extrusion of stainless steels. For this purpose, the ferritic stainless steel X6Cr17 (DIN 1.4016) and the ferritic-austenitic stainless steel X2CrNiMoN22-5-3 (DIN 1.4462) are extruded with an equivalent plastic strain of ε̅ ≈ 1. The research is performed with a molybdenum disulfide (MoS2), a soap and a polymer-based lubricant coating. For reproducing different contact conditions, the die geometry is varied with die opening angles of 60°, 90° and 120°. The suitability of the lubricants is evaluated using the integrity of the lubricant coating after forming. From the correlations between process forces, temperatures and surface integrity, recommendations for the application of the researched lubricants are derived.

Applicable Sensor for a Multivariate Process Controller - Dietrich, Simon; Otto, Andreas (Congress Proceedings ICALEO 2006, 25th International Congress on Application of Laser & Electro-optics, 2006)
LFT Import::2019-08-05 (1327)

Application based PVD-coatings for cold forging tools - Schrader, Tobias; Merklein, Marion; Engel, Ulf (Proc. 6th Int. Conf. and Exhibition on Design and Production of Machines and Dies / Molds, 2011)
LFT Import::2019-08-05 (1637)

Application of a genetic algorithm for the assessment of the capabilities of actuator systems for laser micro adjustment - Plettke, Raoul (International Journal of Material Forming, 2010)
LFT Import::2019-07-29 (149)

Application of a modified ICP-Algorithm in Manufacturing Technology - Hutterer, Angelika; Hagenah, Hinnerk; Otto, Andreas (8th International Fall Workshop, 2003)
LFT Import::2019-08-05 (955)

Application of cemented carbide based forming tools in cold forging - Andreas, Kolja; Noneder, Johannes; Engel, Ulf; Merklein, Marion (Proc. 10th Int. Conf. THE "A" Coatings in Manufacturing Engineering, 2013)
LFT Import::2019-08-05 (1863)

Application of EDM to the production of micro tooling - Herrero, A.; Esmoris, J.; Azcarate, S.; Geißdörfer, Stefan; Engel, Ulf (4M 2007, Third International Conference on Multi-Material Micro Manufacture, 2007)
LFT Import::2019-08-05 (1497)

Application of genetic algorithms for the optimisation of actuator systems for laser micro adjustment. - Plettke, Raoul; Hagenah, Hinnerk; Geiger, Manfred (International Journal of Microstructure and Materials Properties, 2009)
LFT Import::2019-07-29 (135)

Application of genetic algorithms for the optimization of actuator systems for laser micro adjustment - Plettke, Raoul; Hagenah, Hinnerk; Geiger, Manfred (Proceedings of the 6th International Conference on Industrial Tools and Material Processing Technologies 2007 (ICIT&MPT 2007), 2007)
LFT Import::2019-08-05 (143)

Application of Process adapted semi-finished Parts for the Production of Thin-walled Components via Sheet-Bulk Forming - Merklein, Marion; Hildenbrand, Philipp; Schneider, Thomas (AutoMetForm / SFU 2014, 2014)
LFT Import::2019-08-05 (2038)

Application of Tailored Heat Treated Blanks under quasi series conditions - Merklein, Marion; Vogt, Uwe (Proceedings of the 12th International Conference on Sheet Metal (SheMet), 2007)
Tailored Heat Treated Blanks (THTB) are blanks that exhibit locally different strength specifically optimized for the succeeding forming process. The strength distribution is set by a local, short-term heat treatment modifying the mechanical properties of the material. Hence, THTB allow enhancing forming limits significantly leading to shorter and more robust manufacture process chains. In order to qualify the use of THTB under quasi series conditions, the interdependencies of the blank's local heat treatment and the entire process chain of the car body manufacture have to be analyzed. In this respect, the impact of a short-term heat treatment on the mechanical properties of AA6181PX, a commonly used aluminum alloy in today's car bodies, was studied. Also the influence of a short-term heat treatment on the coil lubricant, usually already applied by the material supplier, was given a closer look. Based on these experiments process restrictions for the application of THTB in an industrial automotive environment were derived and a process window for the THTB design was set up. In conclusion, strategies were defined how to enhance the found process boundaries leading to a more robust process window.
LFT Import::2019-08-05 (1388)
Keywords: AA6181PX; Coil lubricant; Process window; Tailored heat treated blanks

Application of Tailor Heat Treated Blanks technology in a joining by forming process - Graser, Matthias; Wiesenmayer, Sebastian; Müller, Martin; Merklein, Marion (Journal of Materials Processing Technology, 2019)
The usage of modern materials in the automotive industry for the body in white construction leads to increasing requirements for the manufacturing process. Due to the limited formability of high-strength aluminium alloys and steels, joining by forming of these dissimilar materials is still a big challenge, which requires suitable and innovative manufacturing technologies. In sheet forming processes the Tailor Heat Treated Blank (THTB) technology allows enhancing the formability of high-strength aluminium alloys. Therefore, the applicability of the THTB technology for the shear-clinching technology is investigated in this paper. Up till now, this innovative joining by forming technology is only qualified to join ductile aluminium alloys and high-strength steels, but the combination of high-strength aluminium and high-strength steel has not been realized yet. In this research work, the limits of the shear-clinching process have been extended to successfully join the material combinations of AA7075 on the punch side and HCT780X, as well as press hardened 22MnB5 on the die side by using aluminium specimens with different heat treatment layouts. Further, this paper shows the possibility to adjust the material flow of the shear-clinching process by local and short-term heat treatment.
CRIS-Team WoS Importer:2019-02-21

Application of the Finite element methods on the staking process of staking fasteners - Tofall, Miriam; Merklein, Marion; Plettke, Raoul (Key Engineering Materials, 2011)
The increasing use of new materials with varying thicknesses within the automotive industry creates high demands on joining elements such as staking fasteners. Simultaneously statements about the feasibility of the design with joining elements already in the early stage of the development are necessary. The challenge is to define suitable element geometry, tool geometry and process parameters. To meet those requirements, a good understanding of the staking process is inevitable. According to the state of the art the examinations regarding the performance of staking fasteners under different conditions are totally conducted experimentally. This trial-and-error procedure leads to an extensive financial effort and to long development times for new elements. It is furthermore not possible to observe all influences of different process parameters. In the field of mechanical engineering the use of numerical simulation for complex constructions is a common technique. This paper deals with the applicability of the finite element method (FEM) on the joining of sheet metals with staking fasteners. In this matter the FEM is used to get scientific insights in the staking process and is also used to identify influencing variables and their interactions. © (2011) Trans Tech Publications.
LFT Import::2019-07-29 (1645)
Keywords: FEM; Mechanical joining; Self-piercing fastener

Applications of Diffractive Optical Elements for High Power Lasers - Hutfless, Joachim; Geiger, Manfred; Lang, A.; Frank, M.; et al. (Proceedings of SPIE, 1994)
Diffractive optical elements for high-power lasers offer interesting applications in addition to conventional refractive and reflective optics like lenses and mirrors. Their function is based on diffraction at small surface structures in the scale of the wavelength. This paper tries to assess realistically the application potential of diffractive optical elements for industrial high-power lasers. These are excimer lasers (λ = 193 ... 308 nm), Nd:YAG solid-state lasers (λ = 1.06 μm) and CO2 lasers (λ = 10.6 μm). After a short description of both the physical fundamentals of diffractive optical elements and their production processes this paper mainly deals with new methods of beam forming and guiding by diffractive optical elements as well as the integration of these optics into laser systems. Hereby the problems arising from high-power densities as well as the possibility of increasing the efficiency of the beam guiding system are stressed.
LFT Import::2019-07-15 (618)

Approach for a sustainable process chain in manufacturing of fasteners for mechanical joining - Uhe, Benedikt; Kuball, Clara-Maria; Merklein, Marion; Meschut, Gerson (Materials Research Proceedings, 2023)

Approach in controlling laser micro spot welding process - Geisel, Mark; Schmidt, Michael (Proceedings of the COST-P4 Workshop Characterization of Manufacturing Process: Synergetics and Data Processing Methods, 2000)
LFT Import::2019-08-05 (776)

A Quick and Simple Test for Abrasive Wear Resistance and its Practical Use. - Vollertsen, Frank; Engel, Ulf (Materialprüfung, 1989)
LFT Import::2019-07-16 (1954)

A reliable methodology to deduce thermo-mechanical flow behaviour of hot stamping steels - Potdar, Bhargav (2017)
This research work focused to accurately determine the thermo mechanical flow behavior of manganese boron steel grade 22MnB5. In general, the true plastic strain obtained in experimental flow curves is lower than that observed in the industrial hot formed parts. Consequently, this work introduces a reliable methodology to deduce thermo-mechanical flow behaviour by using FE-simulations combined with invere optimisatio

A Review on Tailored Blanks - Production, Applications and Evaluation - Merklein, Marion; Johannes, Maren; Lechner, Michael; Kuppert, Andreas (Journal of Materials Processing Technology, 2014)
Tailored Blanks is the collective for semi-finished sheet products which are characterised by a local variation of the sheet thickness, sheet material, coating or material properties. With these adaptions the tailored blanks are optimised for a subsequent forming process or the final application. In principle four different approaches can be distinguished to realise tailored blanks: joining materials with different grade, thickness or coating by a welding process (tailor welded blanks), locally reinforcing the blank by adding a second blank (Patchwork blanks), creating a continuous variation of the sheet thickness via a rolling process (tailor rolled blanks) and adapting the material properties by a local heat treatment (tailor heat treated blanks). The major advantage of products made from tailored blanks in comparison to conventional products is a weight reduction. This paper covers the state of the art in scientific research concerning tailored blanks. The review presents the potentials of the technology and chances for further scientific investigations. © 2013 Elsevier B.V.
LFT Import::2019-07-29 (1911)
Keywords: Forming; Patchwork blanks; Tailor heat treated blanks; Tailor rolled blanks; Tailor welded blanks; Tailored blanks

A ROUND ROBIN STUDY FOR LASER BEAM MELTING IN METAL POWDER BED - Ahuja, Bhrigu; Schaub, Adam; Junker, Daniel; Karg, Michael; Tenner, Felix; Plettke, Raoul; Merklein, Marion; Schmidt, Michael (South African Journal of Industrial Engineering, 2016)
With its ability to fabricate fully dense 3-dimensional structures by selectively melting micro-sized metal powder, the Additive Manufacturing process of Laser Beam Melting (LBM) is being considered by many as a significant complimentary technology to the conventional forming and subtractive manufacturing processes. Even with its industrial acceptance, the LBM process still lacks a high degree of repeatability for the quality of the fabricated structures. This issue is often related to the variation in system technology, process or user influence. In order to fully understand the potential and limitations of the LBM process, the presented paper discusses the design, methodology and results of a round robin test conducted within the Collaborative Working Group (CWG) Lasers in Production at the International Academy of Production Engineering (CIRP). Observed mechanical characteristics for samples from each of the participant are presented. The experiments are designed to obtain data related to mechanical characteristics for different build orientations and processing conditions in addition to the inherent system technology variations. The paper further discusses the observed process phenomena and their association to the induced mechanical characteristics.
Keywords: Additive Manufacturing; Laser Beam Melting; Stainless Steel 15-5 PH; Round Robin; CIRP

A round robin study for Laser Beam Melting in Metal Powder Bed: Comparing mechanical characteristics with system technology variation - Ahuja, B.; Schaub, Adam; Junker, Daniel; Karg, M.; Tenner, F.; Plettke, Raoul; Merklein, Marion; Schmidt, M. (Proc. 15th Annual Conference of RAPDASA 2014, 2014)
LFT Import::2019-08-05 (2095)

A Round Robin study for Selective Laser Sintering of polyamide 12: Microstructural origin of the mechanical properties - Stichel, Thomas; Frick, Thomas; Laumer, Tobias; Tenner, Felix; Hausotte, Tino; Merklein, Marion; Schmidt, Michael (Optics and Laser Technology, 2017)
The mechanical and microstructural investigation of polymer parts (polyamide 12) fabricated by Selective Laser Sintering as part of a Round Robin initiative is presented. The paper focuses on the microstructural analysis of the Round Robin samples and their evaluation regarding their effect on mechanical properties with respect to each other. Therefore optical microscopy on microtomed samples, X-ray computed tomography and Differential Scanning Calorimetry is used to determine the morphology of residual particle cores and of internal pores.The mechanical tensile testing revealed a high variability of the ductility of the samples among the used machines and a distinctive anisotropic mechanical response. Especially the quite brittle characteristic along the building direction has shown to be still a crucial challenge for the process. However, one machine delivered samples with outstanding ductility with total elongation values of about 21% along the building direction and of about 32% planar to the layer. This result was back traced to a distinctive pore and residual particle morphology which is characterized by low pore concentration, the absence of coplanar pore or residual particle arrangements and the highest degree of particle melting measured. Furthermore, the analysis depicts that both features, pores and residual particles, contribute to the mechanical properties significantly and that they are not necessarily linked since they can vary independently in a certain range depending on the machine configuration.
Keywords: Additive manufacturing; Polymers; Polyamide-12; Selective Laser Sintering; Round Robin

A Round Robin study for selective laser sintering of polymers: Back tracing of the pore morphology to the process parameters - Stichel, Thomas; Frick, Thomas; Laumer, Tobias; Tenner, Felix; Hausotte, Tino; Merklein, Marion; Schmidt, Michael (Journal of Materials Processing Technology, 2018)
The mechanical properties of polymer parts built by Selective Laser Sintering are strongly related to the internal microstructure which differs with the applied production parameters. The paper focuses on the back tracing of the pore morphology of laser sintered polyamide-12 samples to the process parameters. Therefore, a data base is used which is supplied by a Round Robin initiative and includes mechanical tensile tests and the microstructural analysis of the pore morphology of several different sample charges built with different machines. The pore morphologies (porosity, pore density, pore shape and pore arrangement) measured by X-ray computed tomography are compared and discussed regarding the employed parameters and the resulting mechanical properties.The investigations point out that pore density is a superior indicator than porosity for mechanical issues. This is especially valid along the build direction since pore morphology has shown to be strongly anisotropic. Moreover, the analysis revealed that pore density is strongly affected by the process temperature, which is proved to be essential for the fabrication of mechanical robust parts using Selective Laser Sintering.
Keywords: Additive manufacturing; Polymers; Polyamide-12; Selective laser sintering; Round Robin; Porosity; Pore density; X-ray computed tomography

Artificial Intelligence in manufacturing: State of the art, perspectives, and future directions - Gao, Robert X.; Krüger, Jörg; Merklein, Marion; Möhring, Hans Christian; Váncza, József (CIRP Annals - Manufacturing Technology, 2024)
Inspired by the natural intelligence of humans and bio-evolution, Artificial Intelligence (AI) has seen accelerated growth since the beginning of the 21st century. Successful AI applications have been broadly reported, with Industry 4.0 providing a thematic platform for AI-related research and development in manufacturing. This paper highlights applications of AI in manufacturing, ranging from production system design and planning to process modeling, optimization, quality assurance, maintenance, automated assembly and disassembly. In addition, the paper presents an overview of representative manufacturing problems and matching AI solutions, and a perspective of future research to leverage AI towards the realization of smart manufacturing.
CRIS-Team Scopus Importer:2024-08-02
Keywords: Artificial intelligence; Machine learning; Smart manufacturing

Artificial intelligence in metal forming - Cao, Jian; Bambach, Markus; Merklein, Marion; Mozaffar, Mojtaba; Xue, Tianju (CIRP Annals - Manufacturing Technology, 2024)
Forming processes are known for their intricacies in prediction and control due to the complex loading conditions and material flow. This paper will first introduce the AI algorithms used or having potential to be used in forming, and then investigate the state-of-the-art advances of AI-based technologies in forming processes with four main pillars of process simulation, process design and optimization, in-situ process control, and qualification and certification of forming processes and formed products. Future directions of AI in forming for both academic research and industrial applications will be proposed to leverage digitalization and data science to explore new solutions in forming processes.
CRIS-Team Scopus Importer:2024-06-14
Keywords: Artificial intelligence; Machine learning; Material characterization; Process control; Process design

Assessing single and multi-step friction stir consolidated recycled billets through uniaxial upsetting test - Latif, Abdul; Ingarao, Giuseppe; Fratini, Livan; Hetz, Peter; Merklein, Marion (Materials Research Proceedings, 2024)
Friction stir consolidation (FSC) represents a solid-state recycling technique that directly transforms machining waste into billets by the stirring action and friction heat of the rotating tool. This technology has demonstrated superior energy efficiency compared to remelting based traditional recycling methods. Concerning the FSC process mechanics, they impart temperature, strain and strain rate gradients across the billet sections leading to variations in mechanical properties such as hardness values and grain size distribution. Therefore, multi-step FSC variants were introduced to eliminate this inherent inhomogeneity inside the billets of the single-step FSC approach. However, the billets manufactured by multi-step methods showed better mechanical properties, and gradation across the billet section still persisted. This property led to the evolution of friction stir consolidation as a new manufacturing method for developing functionally graded materials. Previously, the gradation was highlighted by the Vickers hardness test and grain size distribution. Therefore, in the ongoing study, an advanced characterization technique was adopted by extracting miniaturized samples from the section of FSC billets and subjected them to the upsetting test. Employing advanced characterization techniques to get insights into the gradation and quality of billets manufactured through various process variants and will allow to draw a better conclusion regarding adoption of a more suitable FSC process variant.
CRIS-Team Scopus Importer:2024-06-21
Keywords: Aluminum Alloys; Friction Stir Consolidation; Recycling; Upsetting Test

Assessment of springback behaviour of 800-1200 mpa dual-phase steel grades - Durmaz, Ulas; Heibel, Sebastian; Schweiker, Thomas; Merklein, Marion (Key Engineering Materials, 2021)
Springback occurs in sheet metal forming due to elastic strain recovery after removal of process forces respectively after opening of the tool. For this reason, a precise description of springback requires the elastic stress-strain relationship described by the Young’s modulus as well as the internal stress distribution of the part before unloading. In this context, the Bauschinger effect influences the stress state before springback due to premature plastification during load reversal or load path change. As is well known, the stress-strain curve of a material during unloading is nonlinear because of additional microplastic strain, which is reflected in a decrease of the Young’s modulus. The aim of this work is to characterize the aforementioned phenomena and their effect on springback for three dual-phase steels namely DH800, DH1000 and DP1200LY. For this purpose, cyclic tensile-compression tests as well as loading and unloading loops within uniaxial tensile tests are performed at different plastic strains. To evaluate the springback behaviour of the investigated materials, two different hat-profiles geometries are investigated. By comparing the springback of dual-phase steels on part level, the significance of different material influences with regard to springback is evaluated. The results show that the investigated dual-phase steels exhibit a pronounced Bauschinger effect and a considerable amount of microplastic strain with increasing total strain. However, the comparison between the springback of the hat-profiles and the determined material parameters proves a significant influence of the elastic strain on springback, while microplastic strain and the Bauschinger effect have a minor influence.
CRIS-Team Scopus Importer:2023-03-29
Keywords: Cold forming; Dual-phase steels; Springback

A Theoretical Study on Wear Simulation in Metal Forming Processes - Sobis, Tomasz; Engel, Ulf; Geiger, Manfred (Journal of Materials Processing Technology, 1992)
One of the main reasons of tool failure in industrial application of metal forming technologies is wear. Typical for this kind of failure is that it affects not only the costs of the process but also the tolerances of the formed parts. The only way to control these features is to develop methods which allow prediction of wear and which are suited to be used in the design stage in order to optimize the process. Starting with a survey of prediction methods, a new concept for the simulation of wear is presented in this paper. © 1992.
LFT Import::2019-07-15 (486)

Augmented Reality for Forming Technology - Visualisation of Simulation Results and Component Measurement - Lechner, Michael; Schulte, Robert Karl; Merklein, Marion (IOP Conference Series: Materials Science and Engineering, 2019)
In sheet and bulk forming, numerical simulation has become established over the last 20 years as an indispensable tool for research and industrial practice. The numerical calculation of forming processes supports a time- and cost-efficient development in the context of a virtual product evaluation. Currently, simulation and measurement results are mainly displayed on conventional screens. However, this approach has several disadvantages. On the one hand, only cut-outs can be displayed, especially in the case of large components. A visualisation of entire components in real size is often not possible. On the other hand, no direct comparison with the real components is possible. Augmented Reality is a promising approach to solve the challenges outlined above. As part of the contribution, an innovative approach for component validation based on Augmented Reality technology will be introduced. Thereby, the visualisation using different Augmented Reality devices and the feasibility of a measurement task with Augmented Reality devices will be presented.
CRIS-Team Scopus Importer:2020-02-21

Augmented Reality Technology for the Purpose of Sheet Metal Forming Simulation Evaluation - Lechner, Michael; Schulte, Robert Karl; Meckler, S.; Merklein, Marion (10th Forming Technology Forum 2017 - Model Based Control for Smart Forming Processes, 2017)
LFT Import::2019-08-05 (2276)

A unified model for isothermal and non-isothermal phase transformation in hot stamping of 22MnB5 steel - Hart-Rawung, Thawin; Buhl, Johannes; Horn, Alexander; Bambach, Markus; Merklein, Marion (Journal of Materials Processing Technology, 2023)
The hot stamping of tailored properties is widely established in the automotive industry. However, unlike conventional press hardening, this technique is designed to generate varying mechanical properties by controlling the cooling rate locally. Current material models cannot accurately represent the locally very different thermomechanical paths. This research aims to address this problem by developing a new phase transformation model capable of handling complicated thermal histories and the effects of deformation. A ’unified JMAK‘ model is proposed to capture various thermal-mechanical loading conditions. These conditions include the deformation effect and cooling paths where isothermal conditions range from 450° to 725°C and non-isothermal conditions range from 5° to 40°C/s. Furthermore, for the extension to linear and non-linear cooling paths, correction factors for the phase transformations are introduced into the model. Finally, the model's performance is compared to well-known transformation models, such as the non-isothermal JMAK and the K-V (Kirkaldy and Venugopalan), by comparing the results obtained from isothermal and non-isothermal dilatometer tests and a scaled-down b-pillar experiment. The results from the comparison are classified into 3 cases, isothermal, continuous cooling and non-linear cooling (b-pillar). Case 1 shows that the non-isothermal and K-V models provide low accuracy, while the proposed model yields an error below 2 %. For Case 2, the proposed models and non-iso JMAK are agreeable with the experiment, and the K-V model shows a maximum error of 15 %. Finally, in the b-pillar case study mean absolute errors of hardness predictions are 33.06 HV (mean relative error is 9 %), 43.92 HV (13 %), and 67.70 HV (20 %) for the unified JMAK, non-iso JMAK, and K-V model, respectively.
CRIS-Team Scopus Importer:2023-02-03
Keywords: 22MnB5; Austenite decomposition model; Hot stamping process; Johnson-Mehl-Avrami-Kolmogorov

Aus der Forschung in die Anwendung - RP-Technologien in der Zukunft - Coremans, Arjan; Dierken, R.; Hoffmann, Peter (Tagungsband Forum für innovative Produktentwicklung, 1998)
LFT Import::2019-08-05 (1367)

Ausgewählte Einflussgrößen auf die erzielbaren Verzahnungstoleranzen beim Kaltfließpressen. - Rohrmoser, Andreas; Heling, Björn; Schleich, Benjamin; Hagenah, Hinnerk; Merklein, Marion (Summer School Toleranzmanagement - Beiträge zur 4. Summer School - September 2020, 2020)

Auslegung und Anwendung prozessangepasster Halbzeuge für Verfahren der Blechmassivumformung - Schulte, Robert (Friedrich-Alexander-Universität Erlangen-Nürnberg, 2022)
In the area of tension between ecological and economic challenges, innovative processes are required in the field of production technology in order to be able to meet the increasing demands on new products. In this context, sheet-bulk metal forming represents a promising technology that combines the potentials of established sheet metal and bulk metal forming processes. The central challenges are mainly to ensure sufficient control of the locally varying biaxial and triaxial stress and strain states for the production of near-net-shape functional components. Against this background, the present work deepened and extended the understanding of the process with regard to the design and use of process-adapted semi-finished products in order to be able to increase the material flow control in accordance with the required component properties. As a basis for the investigations, the requirements-based design of a tool geometry to manufacture process-adapted semi-finished products was carried out using a numerical variant simulation, which was subsequently supplemented by a more efficient design approach. The central requirements include the avoidance of identified defect patterns on the externally toothed functional components, which are produced by the single-stage process combination of deep drawing and upsetting. The realisation of a sufficiently high material flow control is one of the basic prerequisites for the efficient production of defect-free functional components made of steel and aluminium alloys in sheet-bulk metal forming processe

Ausstrahlung des Bayerischen Forschungsverbundes Lasertechnik auf den Wirtschaftsstandort Bayern. - Geiger, Manfred; Hoffmann, Peter; Schultz, Markus (Präzisionslaserstrahlfertigungstechnik für den Maschinenbau. Abschlußbericht zum Bayerischen Forschungsverbund Lasertechnik FORLAS, 1996)
LFT Import::2019-08-05 (646)

Auswirkungen spezifischer Abkühlbedingungen auf den Wärmeübergang bei Presshärtprozessen - Svec, Thomas; Merklein, Marion (5. Erlanger Workshop Warmblechumformung, 2010)
LFT Import::2019-08-05 (769)

Automated Brazing of Sheet Metal Parts with Nd:YAG-Laser and 6-Axis-Robot - Hanebuth, Henning; Geiger, Manfred (Proc. of the 5th European Conference on Laser Treatment of Materials ECLAT 94, 1994)
LFT Import::2019-08-05 (610)

Automated Construction Methods for Press Brake Tools - Franke, Volker; Backes, Frank; Geiger, Manfred (Sheet Metal 1996: Proc. of the 4th Int. Conf. on Sheet Metal, 1996)
LFT Import::2019-08-05 (588)

Automated Laser Beam Brazing for the Automobile Body Construction. - Hanebuth, Henning; Hoffmann, Peter; Geiger, Manfred (CIRP-Proceedings - Manufacturing Systems, 1995)
LFT Import::2019-08-05 (561)

Automated Metal Foil LOM - A Novel Technology for Rapid Tooling - Prechtl, Martin; Otto, Andreas; Geiger, Manfred (LIM 2005, Proceedings of the 3rd International WLT-Conference on Lasers in Manufacturing, Munich, 2005)
LFT Import::2019-08-05 (1137)

Automated online planning of localized laser process parameters using simulated annealing - Geiger, Manfred; Klämpfl, Florian; Hagenah, Hinnerk (Production Engineering, 2008)
Today, the planning of the irradiation for most laser applications is carried out by determining global irradiation process parameters like spot size, traverse speed, hatch pattern and laser power. Locally changing properties of the irradiation area are not taken into account. The determination of the process parameters is done offline by simulation and experiments. However, there are situations where this is not feasible, the laser process must be planned in more detail. In this paper, the core algorithms used for a localized planning of the irradiation process will be presented. This planning is carried out using a heuristic optimization algorithm, so-called simulated annealing. Besides the description of the used algorithms and an overview of the surrounding algorithms and system technology of a sample application, results which demonstrate that the algorithms work well will be shown. © German Academic Society for Production Engineering (WGP) 2007.
LFT Import::2019-07-29 (261)
Keywords: Computer aided engineering; Laser process planning; Optimization

Automatische Arbeitsplanung für Blechbiegeteile - Geiger, Manfred; Backes, Frank; Franke, Volker; Greska, Wolfgang (Technica, 1994)
LFT Import::2019-07-15 (462)

Automatisiertes Schichtverfahren für metallische Folien - System- und Prozesstechnik - Prechtl, Martin (Friedrich-Alexander-Universität Erlangen-Nürnberg, 2006)
The new process chain of Automated Metal Foil LOM enables the rapid fabrication of Tools or tool Elements based on 3d CAD data. It is of Special importance in the field of injection moulding. As the manufacture is done layer by layer complex geometries outside the tool as well as integrated 3d ducts can be realized. Hence, the replacement of cost and time intensive eroding processes and the creation of moulds with a controllable thermal behaviour are the main potential of application. The latter subject is used for reducing the cycle time and for optimizing the resulting properties of the parts. Summing up, the Automated Metal Foil LOM may expand the Performance of mould and tool making in the future and therefore it could satisfy the current requirements of the Industry concerning this applicatio

Basic experimental and numerical investigations on chip pressing - Grüner, Martin; Merklein, Marion (Key Engineering Materials, 2013)
Aluminium alloys show a great potential for lightweight constructions due to their high strength and low density but the production of this material is very energy consuming. Also the recycling of aluminium alloys, e.g. chips from the milling process, shows different challenges. Beside contamination by cooling lubricant and oxidation of the surface of the chips the melting and rolling process for new semi finish products needs a high amount of energy. TEKKAYA shows a new approach for recycling of aluminium alloy chips by an extrusion process at elevated temperatures producing different kinds of profiles. A new idea is the production of components directly out of chips using severe plastic deformation for joining of the chips similar to the accumulative roll bonding process in sheet metal forming. In a first approach aluminium alloy chips out of a milling process were uniaxial compressed with different loads inside an axisymmetric tool installed in a universal testing machine. The compressed chip disks subsequently were tested with two experiments to gain information on their stability. First experiment is a disk compression test with the disk standing on its cylindrical surface, giving information on the stability perpendicular to the compression direction. Second experiment is a stacked disk compression test with three disks to investigate the stability parallel to compression direction. During all three tests force and displacement values are recorded by the universal testing machine. These data are also processed to calculate or identify input parameters for the numerical investigations. For numerical simulation ABAQUS in conjunction with the Drucker-Prager-Cap material model, which is often used for sintering processes, seems to be a good choice. By numerical simulation of the experiments and comparison with the experiments input parameters for the material model can be identified showing good accordance. This material model will be used in future numerical investigations of an extrusion process to identify tool geometries leading to high strains inside the material and by this to an increased stability of the parts. Copyright © 2013 Trans Tech Publications Ltd.
LFT Import::2019-07-29 (1890)
Keywords: Aluminum alloys; Chip pressing; Drucker-prager-cap; Recycling

Basic Investigations of Non-Pre-Punched Joining by Forming of Aluminium Alloy and High Strength Steel with Shear-Clinching Technology - Merklein, Marion; Meschut, Gerson; Müller, Martin; Hoerhold, Rejane (Key Engineering Materials, 2014)
LFT Import::2019-07-29 (2017)
Keywords: Clinching; FEM; Joining by forming; Lightweight design; Multi-material mix

Basic investigations on boundary lubrication in metla forming processes by in situ observation of the real contact area - Weidel, Stephan; Engel, Ulf; Merklein, Marion; Geiger, Manfred (Production Engineering, 2009)
LFT Import::2019-07-29 (1576)

Basic investigations on hot sheet metal forming of quenchable high strength steels - Geiger, Manfred; Merklein, Marion; Lechler, Jürgen; Bach, F.W.; Springer, R.; Kleiner, M.; Tekkaya, A.E.; Homberg, W.; Brosius, A.; Karbasian, H.; et al. (2nd International Conference on New Forming Technology, 2007)
LFT Import::2019-08-05 (1460)

Basic Investigations on Hot Stamping of Tailor Welded Blanks Regarding the Manufacturing of Lightweight Components with Functionally Optimized Mechanical Properties - Lechler, Jürgen; Stöhr, Thomas; Kuppert, Andreas; Merklein, Marion (Transactions of the North American Manufacturing Research Institute of SME, 2010)
The combination of two innovative technologies, the application of tailored products on the one hand and hot sheet metal forming on the other, allows to achieve final component properties, that could not be realized so far. Within this work major research activities are described concerning material engineering, which have been carried out within the scope of component and process development of hot stamping of tailor welded blanks (TWB). This includes basic analyses related to the selection of an appropriate steel grade. For the finally selected and with an aluminum-silicon layer pre-coated steel grade HX340 LAD+AS150 investigations have been performed to determine the thermo-mechanical properties of the material subject to the most important process parameters during hot stamping. In addition special emphasis is placed on the description of the weld seam properties and the forming and failure behavior of hot stamping TWBs under process relevant conditions.
LFT Import::2019-07-29 (1161)
Keywords: 22MnB5; Hot stamping; HX340 LAD+AS150; Mechanical properties; Tailor welded blanks

Basic investigations on the hot stamping steel 22MnB5 - Geiger, Manfred; Merklein, Marion; Hoff, Cornelia (Sheet Metal 2005, Proceedings of the 11th International Conference on Sheet Metal, 2005)
Basic research concerning the material properties of the hot stamping steel 22MnB5 has been carried out. A survey is given about the as-delivered conditions with hardness tests, micrographs and flow curves. The process window of the austenitization time, before hot stamping can take place, is defined by austenitization tests. Also a new experimental set-up to detect the cooling rate in dependency on the contact pressure is presented. In addition to that the cooling experiments were simulated with ABAQUS and the heat transfer coefficient for each contact pressure is determined by inverse modeling.
LFT Import::2019-08-05 (1130)
Keywords: Heat treatment; Hot stamping; Sheet metal

Basic numerical analysis of a “Samanta” based forward extrusion process - Kiener, Christoph; Andreas, Kolja; Merklein, Marion (Advanced Materials Research, 2016)
LFT Import::2019-07-29 (2181)

Basic research on cold and warm forging of microparts - Engel, Ulf; Egerer, Emil (Key Engineering Materials, 2002)
The application of metal forming to the manufacturing of microparts is still not widespread. The reason is that the know-how of conventional technologies cannot be simply transferred to the microscale. This is due to so-called size effects, which in cold forging can be observed in terms of effects on material flow, on tribological behavior, and on working accuracy. Scaled experiments reveal that there is a transition from homogeneous to inhomogeneous continuum which can be characterized by the ratio between grain size and part size. For a given ratio, the transition can be shifted by processing at elevated temperatures yielding a more homogeneous deformation, thus improving the accuracy and reproducibility of the microforming process.
LFT Import::2019-07-16 (1665)
Keywords: Cold forming; Micro forming; Warm forming

Basics for inline measurement of tribological conditions in series production of car body parts - Hansen, B.; Hoebler, M.; Purr, S.; Meinhardt, J.; Merklein, Marion (IOP Conference Series: Materials Science and Engineering, 2019)
The quality of car body parts in series production is strongly dependent on the tribological behavior. Fluctuating material properties such as the sheet roughness and the amount of lubricant have an influence on the forming process. On the basis of large amounts of data it is possible to investigate the friction behavior in series production and to make process adjustments if required. Therefore, inline measurement systems have a great potential to detect the sheet roughness during the cutting process of blanks in the coil line. Furthermore, contactless systems are advantageous as they do not damage the surface. Nevertheless, the optical measuring is influenced by the lubricant layer on top of the surface. Therefore, the previously unknown impact of the lubricant on the measuring result is investigated. Within this study, stationary optical roughness measurements have been conducted using different amounts of lubricant on hot-dip galvanized EDT steel. The results demonstrate the influence of different amounts of lubricant on the sheet roughness measurement. Hence, it is possible to correct the inline measuring results and gain knowledge of fluctuating surface roughness. In addition, strip drawing test has been carried out to investigate the effect of fluctuating tribological conditions.
CRIS-Team Scopus Importer:2020-02-21