Basics of process design for 3d freeform-bending - Plettke, Raoul; Vatter, Peter; Vipavc, Daniel (Steel Research International, 2012)
Three-roll-push-bending is an innovative freeform bending process for the production of complex tube geometries with a variable distribution of curvature and torsion. The process design is complicated since there are a lot of parameters which have an impact on the formation of the bending arc. In industrial application a trial-and-error approach is commonly used. This paper presents a method for the process design of 3-dimensional freeform bended tubes. It defines a format to describe the associated geometries mathematically in a way that corresponds with the machine parameters. The mathematical description is based upon a discrete application of the Frenet-Serret formulations on common CAD file formats. The correlation between process parameters and resulting geometry, given by its curvature and torsion, has been examined. Moreover, the paper describes how to retrieve suitable process parameters using a characteristic map. The method can be utilized in process design, as well as to identify the parameters of a bended tube for quality control purposes. It was applied and first sampling points are presented. To describe the linear dependency between the rotation of the feeding arm and the tube's torsion, a new variable called the torsion adjustment coefficient will be introduced. © 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.
LFT Import::2019-07-29 (1784)
Keywords: Process design; Three-roll-push-bending; Tube bending

Basic Study on the Influence of Liquid Lubricant on Contact State in Cold Forging Processes - Weidel, Stephan (UTF-Science, 2009)
LFT Import::2019-07-29 (1577)

Beanspruchungsangepasste Bauteileigenschaften durch effiziente, optimierte Kaltumformprozesse - Völkl, Ralf; Werner, N.; Neher, R.; Engel, Ulf; Zimmermann, Andrea (Neuere Entwicklungen in der Massivumformung, 2013)
LFT Import::2019-08-05 (1918)

Beanspruchungsangepasste Kaltmassivumformwerkzeuge durch lokal optimierte Werkzeugoberflächen - Wagner, Kay (Friedrich-Alexander-Universität Erlangen-Nürnberg, 2012)
The scope of this work was the research of maximumstressed cold forging tools, where fatigue as well as wear arise and lead to an early tool failure. Therefore the treatments Hard Roller Burnishing, Heat Treatment by Laser as well as Laser Texturing were tested. On the basis of basic studies the effective applicability of the surface treatment procedures at high-strength materials in cold forging was proven and example tools were successfully used in serial productio

Beanspruchungserfassung für die Validierung von FE-Modellen zur Auslegung von Massivumformwerkzeugen - Noneder, Johannes (Friedrich-Alexander-Universität Erlangen-Nürnberg, 2014)
Validating FE-models for tool design of highly loadable tools for forming of very strain hardening materials is challenging. This thesis presents a methodology for enhancing validation of FE-models to achieve better tool load prediction of the FE-models. This is fundamental for designing of highly loadable tools for cold forging of high nitrogen steels. Using these materials enables the production of high strength components without the need of quenching and temperin

Beanspruchungsgerechte Oberflächenstrukturierung hartstoffbeschichteter Werkzeuge der Kaltmassivumformung - Geiger, Manfred; Engel, Ulf; Popp, Uwe (Bayerischer Forschungsverbund für Oberflächentechnik, 2000)
LFT Import::2019-07-15 (763)

Beanspruchungsgerechte Oberflächenstrukturierung hartstoffbeschichteter Werkzeuge der Kaltmassivumformung - Geiger, Manfred; Engel, Ulf; Popp, Uwe (Bayerischer Forschungsverbund für Oberflächentechnik, 2001)
LFT Import::2019-07-15 (862)

Bearbeitung von Blechteilen mit CO2-Hochleistungslasern - Geiger, Manfred; Hoffmann, Peter; Biermann, Stefan; Nuss, Rudolf (Laser/Optoelektronik in der Technik, 1989)
LFT Import::2019-07-15 (433)

Beeinflussung der Werkzeuglebensdauer durch werkzeugseitige Anpassungen - Andreas, Kolja (Tagungsband XXXIII. Verformungskundliches Kolloquium, 2015)
LFT Import::2019-08-05 (2106)

Behavior of the grain structure in micro sheet metal working - Eckstein, Ralf; Engel, Ulf (Metal Forming, 2000)
LFT Import::2019-07-15 (751)

Behaviour of a High Viscous Fluid and its Effect on the Flow Influenced Hydroformnig Process - Dal Bò, Paolo; Geiger, Manfred (Tagungsband der Femlab Konferenz: Neue Wege der Multiphysik-Simulation, 2006)
LFT Import::2019-08-05 (1346)

Beitrag zur automatisierten Handhabungsplanung komplexer Blechbiegeteile - Vormann, Bodo (Friedrich-Alexander-Universität Erlangen-Nürnberg, 1995)
The aim of this thesis was the determination of methods for the automated planning of handling operations for complex bending parts. To reach this aim an object-oriented modelling technique was used. By means of this method models for the static, dynamic and functional behaviour of handling components were derived. One of the features of these models is their high degree of flexibility to describe multiple variations of commercial handling components offered by the manufactures. The derived model was accomplished and integrated in an planning system for die bending parts. This system also included a component for the planning of bending sequences. By means of this system a fully automatic and flexible production planning of the bending process has been made possible with consideration of handling aspect

Beitrag zur Beurteilung des Bruchverhaltens von Hartmetall-Fließpreßmatrizen - Wissmeier, Hans-Jürgen (Friedrich-Alexander-Universität Erlangen-Nürnberg, 1990)
In der Arbeit wurden handelsübliche Hartstoffe auf Wolframkarbid-Basis auf ihr Bruchverhalten hin untersucht und Aufschlüsse über den Ablauf des Werkzeugbruchs bei Fließpressmatrizen gewonnen. Die mechanische Beanspruchung wurde mit Hilfe der Finite-Elemente-Methode berechnet. Die Rechnungen zeigten im Schultereinlaufradius eine Spannungsspitze mit Zug-Druck-Schub-Beanspruchung. Bei einem angenommenen Anriss wurde das Risswachstum berechnet. Der Vergleich von statischer und zyklischer Biegebruchfestigkeit zeigte, dass von der statischen nicht auf die Wechselfestigkeit geschlossen werden kann. Bruchversuche mit überlagerten Zug- und Druckspannungen ergaben, dass bei den praxisüblichen Druckspannungswerten bis ca. 2.000 N/mm2 für die betrachteten Werkstoffe die Normalspannungshypothese angesetzt werden kann. Bruchauslösend waren Gefügefehler unter der Probenoberfläche, es kam nicht zur Bildung von Oberflächenrissen. Eine Werkstoffoptimierung sollte daher die Verringerung der Zahl der Gefügefehler anstreben. Die Ergebnisse der Arbeit zeigten, dass ein „Leben mit dem Riss“ möglich ist, wenn dieser auf relativ kurzer Distanz auf eine Druckspannungszone stößt. Die praxisüblichen Werkzeugbelastungen liegen im groben Streubereich der Bruchfestigkeiten dieser Werkstoffe. Zur Auslegung von Fließpreßmatritzen sollten daher statistische Aussagen von Bruchversuchen, auch mit Unterstützung von Finite-Elemente-Rechnungen, einbezogen werde

Beitrag zur gezielten Beeinflussung des Werkstoffflusses beim Innenhochdruck-Umformen von Blechen - Vahl, Meik (Friedrich-Alexander-Universität Erlangen-Nürnberg, 2005)
Lightweight design is a strongly ongoing trend especially in the automotive industry that is pursued by the use of modern materials and manufacturing technologies, like sheet metal hydroforming. . Within this book, a systematic analysis by simulation and experiments of an active counter punch system used to influence the forming process of complex parts by sheet metal hydroforming is described. The effects of tribological conditions, non-linear strain paths and the used material model in the FE-analysis as well as the design of an efficient multi step forming process are described and deliver details for the process planning enginee

Beitrag zur Mikromaterialbearbeitung mit Excimerlasern - Systemkomponenten und Verfahrensoptimierungen - Rebhan, Thomas (Friedrich-Alexander-Universität Erlangen-Nürnberg, 1996)
The aim of the thesis is to increase the ablation rate of excimer laser material processing and thereby to promote the industrial applications. This should be realized by fundamental technology experiments and process optimization. For the first time a diffractive optical element (phase element) was used for XeCl excimer laser processing. The ablation rate increases by a factor of 3 to 4 for the used ring shaped focus in comparison to the conventional mask projection technique. The ablation rate of Al2O3-processing increases through the modification of the physical boundary conditions. If Al2O3 is processed in water the ablation rate is increased by an order of magnitude because water vaporizes explosively based on superheating. The application potential of excimer laser radiation in industry is improved because of the increase in efficiency (higher ablation rate, reduced optical losses

Beitrag zur rechnerunterstützten verursachungsgerechten Angebotskalkulation von Blechteilen mit Hilfe wissensbasierter Methoden - Knoblach, Jürgen (Friedrich-Alexander-Universität Erlangen-Nürnberg, 1999)
Excimer laser processing offers new possibilities for the surface finishing of ceramics which exceed and/or complete the variety of conventional finishing methods. In order to optimize the surface topography of ceramics for lubricated sliding applications, two different ways of surface treatment by excimer laser radiation are examined: One is the homogeneous modification of the surface topography, i.e. reducing or increasing the roughness or waviness of the ceramics depending on the laser processing parameters. The other possibility is the microstructuring of the surface by a mask projection technique. The surface structures act as lubricant pockets and generate hydrodynamic pressures in the lubricant at high sliding velocities and thus support a full lubricant-film separation of the contact bodies of the bearing. The experimental results indicate that the load-carrying capacity of ceramic bearings is improved both by a homogeneous modification of the surface topography and by the microstructuring of the surface. A significant increase of the lubricant film thickness can be achieved for both examined alternatives. The regime of elastohydrodynamic lubrication could possibly be extended to lower sliding velocities; this could minimize wear-intensive boundary lubrication at frequent starting and running-out procedure

Beitrag zur Untersuchung der tribologischen Bedingungen in der Blechmassivumformung - Bereitstellung von tribologischen Modellversuchen und Realisierung von Tailored Surfaces - Vierzigmann, Ulrich (Friedrich-Alexander-Universität Erlangen-Nürnberg, 2016)
Within this research work a methodology for investigating the tribological conditions within sheet-bulk metal forming has been developed and realized. For the first time it is possible to investigate the different appearing load cases within sheet-bulk metal forming operations with the same sheet metal raw material by using the strip drawing test and the specifically adapted ring and pin extrusion test. Thus, the friction coefficient as well as the friction factor can be determined under comparable conditions, which is essential for numerical investigations. With this methodology it is possible to recommend suited tribological systems for sheet-bulk metal forming by investigating different lubricants and workpiece topographies towards their applicability. Furthermore, the studies on tailored surfaces, which are locally adapted workpiece surfaces, have shown that it is possible to influence the material flow in sheet-bulk metal forming in a directed way and thus to achieve a significant increase in mold fillin

Bendability of advanced high strength steels - A new evaluation procedure - Kaupper, Markus; Merklein, Marion (CIRP ANNALS - Manufacturing Technology, 2013)
The significant lightweight engineering potential of advanced high strength steels (AHSS) is limited by its moderate formability and altered failure behavior compared to mild steel grades. Especially bendability is crucial in automotive applications. The failure phenomena and underlying damage mechanisms in small curvature bending of AHSS are revealed in this work. A new characterization approach based on optical strain measurement is presented to comprehensively identify the failure stages, critical strains and bending angles in a user-independent manner. The novel approach is generalized and broadly applicable. Thus it gives a prerequisite for improved and material specific industrial process design in future. © 2013 CIRP.
LFT Import::2019-08-05 (1891)
Keywords: Bending; Forming; High strength steel

Bend Better with Lasers - Vollertsen, Frank; Geiger, Manfred (Forming & Fabrication, 1995)
LFT Import::2019-07-15 (577)

Bending behavior of a hot stamped complex phase steel with tailored properties by local carburization - Horn, Alexander; Merklein, Marion (IOP Conference Series: Materials Science and Engineering 1157, 2021)
CRIS-Team WoS Importer:2021-11-05

Bending of high-strength low-alloyed steel with respect to edge crack sensitivity caused by shearing operations - Tsoupis, Ioannis; Hildering, Sven; Merklein, Marion (Procedia Engineering, 2014)
LFT Import::2019-07-29 (2036)
Keywords: Bending; Blanking; Fracture analysis

Berechnung der Wechselwirkungen zwischen Umformmaschine und -prozess auf Basis der Integration eines Pressenmodells in die FE-Fließpresssimulation - Kroiß, Thomas; Völkl, Ralf; Engel, Ulf (Proc.12th Dresdner Werkzeugmaschinen-Fachseminar, 2007)
LFT Import::2019-08-05 (495)

Berücksichtigung funktionsrelevanter Gestaltabweichungen bei der Auslegung von Umformprozessen zur Herstellung von Stirnrädern mit Sonderverzahung durch Fließpressen - Rohrmoser, Andreas; Hagenah, Hinnerk; Merklein, Marion (Industriekolloquium der Forschungsgruppe FOR 2271, 2019)
LFT Import::2019-08-05 (2355)

Berücksichtigung von produktionsspezifischen Abweichungen im interdisziplinären Toleranzmanagement - Heling, Björn; Oberleiter, Thomas; Rohrmoser, Andreas; Kiener, Christoph; Schleich, Benjamin; Hagenah, Hinnerk; Merklein, Marion; Willner, Kai; Wartzack, Sandro (Industriekolloquium der Forschergruppe FOR 2271, 2019)
LFT Import::2019-08-05 (2353)

Berührungslose Formgebung mit Laserstrahlung - Holzer, Stefan (Friedrich-Alexander-Universität Erlangen-Nürnberg, 1996)
Depending on the parameters laser forming shows three different mechanisms, which allow concave and convex bendings and in-plane contraction. The development of suitable FEM models and a systematic experimental validation improved the knowledge about this process especially by the calculation of quantities, which cannot be acquired by experiments. The temperature-gradient-mechanism (TGM) uses the temperature difference between the irradiated and the non-irradiated surface in order to obtain a concave bending, which is defined by a movement of one bending leg towards the heat source. For high-precision bending with the TGM a closed-loop was designed. Several control strategies were discussed, which allow in principle any desired accuracy. A totally different mechanism is working if the irradiation time increases and the temperature gradient lowers. If the diameter of the heated area is big compared to the sheet thickness, the thermal stresses may cause buckling. This buckling mechanism allows convex bendings. The third mechanism is activated also by a homogenous heating of the total sheet thickness. If the diameter of the heated area is too small in order to cause buckling, the thermal stresses will cause an in-plane contraction. Analytical and numerical calculation models for these effects meet the basic requirements for a successful usage of laser forming for accurate alignment and rapid-prototypin

Beschichtungssysteme auf AlCrN-Basis für das Presshärten - thermische Kennwertermittlung für Werkzeug und Werkstoff - Wieland, Michael; Merklein, Marion (4. Erlanger Workshop Warmblechumformung, 2009)
LFT Import::2019-08-05 (308)

Beschreibung des mechanischen Werkstoffverhaltens beim Warmumformen höchstfester Stähle - Stöhr, Thomas; Merklein, Marion (Tagungsband 5. Erlanger Workshop Warmblechumformung, 2010)
LFT Import::2019-08-05 (744)

Beschreibung des mechanischen Werkstoffverhaltens beim Warumumformen höchstfester Vergütungsstähle - Geiger, Manfred; Merklein, Marion; Lechler, Jürgen (1. Erlanger Workshop Warmblechumformung, Tagungsband zum Berichts- und Industriekolloquium der FOR552, Erlangen, 7. November 2006, 2006)
LFT Import::2019-08-05 (1340)

Beschreibung und Modellierung des Werkstoffverhaltens von presshärtbaren Bor-Manganstählen - Lechler, Jürgen (Friedrich-Alexander-Universität Erlangen-Nürnberg, 2009)
Within the scope the thesis methodologies regarding the characterization of the forming and phase transformation behaviour of the quenchenable high strength steel 22Mn85 under process relevant conditions of hot stamping will be presented. The main focus of the work hereby deals with the description and modelling of the flow behaviour of the boron-manganese steel in dependency of the influencing process characteristic

Bestimmung des Brechungsindex des Schmiermittels Beruforge 152DL unter Verwendung eines dafür entwickelten Dünnschichtnormals - Metzner, Sebastian; Reuter, Tamara; Wirthmann, Elisa; Hausotte, Tino (20. GMA/ITG-Fachtagung Sensoren und Messsysteme 2019, 2019)
Für eine Messung von blechmassivumgeformten Bauteilen möglichst nahe am Fertigungsprozess spielen systematische Abweichungen durch den darauf noch verbliebenen Schmierstoff eine signifikante Rolle. Die erwartete Schichtdicke dieses Schmierstoffs liegt bei den betrachteten Bauteilen in einem Bereich von unter 35 μm. Für die Bestimmung des Brechungsindex des Schmiermittels und somit die Auswirkungen des Schmierstoffs auf die interferometrische Messung, wird ein Dünnschichtnormal vorgestellt, welches in einem Bereich von 6 bis 100 μm einen kontinuierlichen Messbereich abbildet. Mit dem eingesetzten Messverfahren, einer koaxialen interferometrischen Schichtdickenmessung, können so in verschiedenen Abständen die optische Dicke bestimmt werden. Daraus lässt sich im Anschluss der Brechungsindex näherungsweise bestimmen. Zudem können die Abweichungen der angezeigten Schichtdicke bei bekanntem Brechungsindex nun bewertet werde

Beurteilung des Glanzgrades an Blechen durch 3D-Oberflächenanalyse - Geiger, Manfred; Engel, Ulf; Leopold, J.; Krauß, Hans-Joachim; Günther, H.; et al. (Blech, Rohre, Profile, 1999)
LFT Import::2019-07-16 (2008)

Bewertung des Vorspannungszustandes von armierten Werkzeugsystemen - Putz, Alexander (UTF-Science, 2001)
LFT Import::2019-07-15 (829)

Bewertung von Fertigungsplänen der Blechverarbeitung in Abhängigkeit von der erreichbaren Bauteilgenauigkeit - Hagenah, Hinnerk; Knoblach, Jürgen (Qualitätsfaktor Umformtechnik: Tagungsband der 5. Sächsischen Fachtagung Umformtechnik in Freiberg, 1998)
LFT Import::2019-08-05 (1149)

Biegen mit Excimerlasern. - Becker, Wolfgang; Geiger, Manfred (Europäischer Laser-Markt, 1996)
LFT Import::2019-07-15 (586)

Biegen von höhenfesten Stahlblechwerkstoffen - Umformverhalten und Grenzen der Biegbarkeit - Kaupper, Markus (Friedrich-Alexander-Universität Erlangen-Nürnberg, 2012)
Das Leichtbaupotenzial von höherfesten Stahlblechwerkstoffen wird durch deren moderate Umformbarkeit und das veränderte Versagensverhalten im Vergleich zu konventionellen Stählen eingeschränkt. In der Arbeit wurden deshalb das Umformverhalten und die Umformgrenzen beim scharfkantigen Biegen derartiger moderner Stähle grundlegend untersucht, ein vertieftes Verständnis für die auftretende Schädigung und deren Beeinflussbarkeit geschaffen sowie eine neue Methodik zur quantitativen und benutzerunabhängigen Analyse der Versagensstadien beim Biegen entwickelt und werkstoffübergreifend validiert. Damit liegen neue Methoden und Erkenntnisse für die industrielle Praxis der Biegeumformung vor, welche die Grundlage für eine verbesserte und werkstoffgerechte Prozess- und Bauteilgestaltung darstelle

Biegeumformen mit Elastomerwerkzeugen : Modellierung, Prozessauslegung und Abgrenzung des Verfahrens am Beispiel des Rohrbiegens - Nock, Marco (Friedrich-Alexander-Universität Erlangen-Nürnberg, 2005)
Decreasing product cycle times as well as more and more individual prospects on products make modern manufacturing technologies necessary which enable an efficient and flexible production of parts. A group of technologies fulfilling these demands is forming using an elastomere tool. This work shows, exemplarily for bending of tubes using an elastomere pad, strategies for a virtual process design as well as for an online process control. For a virtual process design by using finite element simulation, suitable methods for the characterisation, for the choice of a material model and the modelling of the process are presented. Within the scope of a process control a foil measurement system has been realised. By using this system contact stresses between elastomere tool and workpiece can be detected and monitored. The potential of the technology of bending using an elastomere tool is shown on the basis of the resulting properties of the produced part

Biegewerkzeuge aus laserstrahlgeschnittenen Lamellen - Geiger, Manfred; Franke, Volker (Blech, Rohre, Profile, 1995)
LFT Import::2019-07-15 (469)

Blank hydroforming using granular material as medium - investigations on leakage - Grüner, Martin; Gnibl, Tobias; Merklein, Marion (Procedia Engineering, 2014)
LFT Import::2019-07-29 (2032)
Keywords: Granular material; Hydroforming; Leakage

Blechbearbeitung an der Schwelle zum 21. Jahrhundert - einige Visionen aus jüngster Forschung. - Geiger, Manfred; Hoffmann, Peter; Vollertsen, Frank; Müller, Burkhard (20 Jahre Umformtechnik in Darmstadt (1996), 1996)
LFT Import::2019-08-05 (648)

Blechbearbeitung durch Laserstrahlschneiden - Beeinflussung der Werkstoffeigenschaften durch den Schneidvorgang - Geiger, Manfred; Bergmann, H.W.; Nuss, Rudolf (Blech, Rohre, Profile, 1988)
LFT Import::2019-07-15 (274)

Blechmassivumformung - Stand der Technik und Ausblick - Merklein, Marion; Hagenah, Hinnerk; Schneider, Thomas (2. Workshop Blechmassivumformung, 2013)
LFT Import::2019-08-05 (1925)

Blechmassivumformung – vom Halbzeug zum Funktionsbauteil - Merklein, Marion; Schneider, Thomas; Gröbel, Daniel; Nürnberger, F. (21. Umformtechnisches Kolloquium Hannover, Industrie und Wissenschaft – Gemeinsam die Zukunft gestalten, 2014)
LFT Import::2019-08-05 (2010)

Blockchain for forming technology - Tamper-proof exchange of production data - Frey, Philipp; Lechner, Michael; Bauer, T.; Shubina, Tatyana; Yassin, Antonia; Wituschek, Simon; Virkus, Maximilian; Merklein, Marion (IOP Conference Series: Materials Science and Engineering, 2019)
An increasingly connected production in the sense of Industry 4.0 allows completely new possibilities in regard to improved and more efficient production and higher product quality. But a key factor to Industry 4.0 is a consistent data flow along the production chain. However, the exchange of data, especially between companies, still is a major obstacle to overcome in order to achieve the aforementioned advantages. Currently, there are increasing efforts to record and analyse data. But there is a lack of a holistic system to handle data, therefore commonly company databases or other inefficient methods are used. These solutions are limited with regard to data exchange since the ownership of data cannot be proven, production data has no unforgeable timestamp, which in turn hinders the generation of complete production history from the final product (e.g., car door) back to the semi-finished product (e.g., steel sheet). As a result, there is insufficient to no data exchange along the production chain. In order to solve these problems blockchain is a promising approach. At the Institute of Manufacturing Technology, an operational blockchain system was developed and implemented using standard production machines. With the combination of a quarto rolling mill and a 400t - press, representing the sheet metal supplier and a forming company, respectively, the typical process chain of sheet metal processing is represented, which allows the detailed investigation of the established blockchain in this field of application. Within this contribution, the conceptual approach of a blockchain system for forming technology will be presented. The nature and the classification of occurring data throughout the production chain will be addressed.
CRIS-Team Scopus Importer:2020-02-21

Blockchain in sheet metal processing. - Lechner, Michael; Christ, T.; Frey, Philipp; Wituschek, Simon; Arzhanov, A.; Petrov, F.; Merklein, Marion (wt Werkstattstechnik - Online, 2020)
The ability to both track physical products and to gather a production data record are important elements of modern manufacturing processes and crucial requirements for an end-to-end digital production. This work presents a solution for both challenges based on the combination of two systems: While a blockchain-based data exchange platform ensures that the requirements towards networked processes are met, an optical technology for marker-free identification of component parts is used.
CRIS-Team Scopus Importer:2021-04-19

Blockchain-Systeme für den manipulationssicheren Datenaustausch in der industriellen Fertigung: Distributed Ledgers für den Materialdatenaustausch - Lechner, Michael; Frey, Philipp; Kreß, Maximilian; Christ, T.; Charlet, C.; Merklein, Marion (wt Werkstattstechnik - Online, 2021)
Modern industrial manufacturing processes have to meet ever-increasing requirements in terms of material and resource efficiency, quality and product variety. The cross-company consolidation of integrity-secured data is a prerequisite for the retrospective identification of quality problems, the documentation of compliance with standards and the allocation of resource consumption along the value chain. This paper uses the example of a material characterization process for hybrid lightweight construction processes to discuss how blockchain technology can be used to implement a tamper-proof storage concept.
CRIS-Team Scopus Importer:2023-03-29
Keywords: Digitalisierung; Industrie 4.0; Werkstoffe

Bruchkriterien für die Auslegung von Hartmetall-Fließpressen - Geiger, Manfred; Engel, Ulf; Wissmeier, Hans-Jürgen (Neuere Entwicklungen in der Massivumformung, 1989)
LFT Import::2019-08-05 (443)

Bruchkriterien für die Auslegung von Hartmetall-Fließpreßmatrizen - Wissmeier, Hans-Jürgen; Engel, Ulf; Geiger, Manfred (Draht, 1990)
LFT Import::2019-07-15 (741)

Bruchverhalten von WC Co Hartmetallen unter wechselnder Belastung. - Wissmeier, Hans-Jürgen; Engel, Ulf (DVM Berichtsband der Tagung "Werkstoffprüfung 1988", 1988)
LFT Import::2019-08-05 (1958)

Bulk forming of sheet metal - Merklein, Marion; Allwood, Julian; Behrens, Bernd-Arno; Brosius, Alexander; Hagenah, Hinnerk; Kuzman, Karl; Mori, Ken-ichiro; Tekkaya, A. Erman; Weckenmann, Albert (CIRP Annals - Manufacturing Technology, 2012)
Ever increasing demands on functional integration of high strength light weight products leads to the development of a new class of manufacturing processes. The application of bulk forming processes to sheet or plate semi-finished products, sometimes in combination with conventional sheet forming processes creates new products with the requested properties. The paper defines this new class of sheet-bulk metal forming processes, gives an overview of the existing processes belonging to this class, highlights the tooling aspects as well as the resulting product properties and presents a short summary of the relevant work that has been done towards modeling and simulation. © 2012 CIRP.
UnivIS-Import:2015-03-09:Pub.2012.tech.FT.FT-QMFMT.bulkfo
Keywords: Forming; Processes; Sheet-bulk

Bulk Metal Forming of Additively Manufactured Elements - Papke, Thomas; Junker, Daniel; Schmidt, Michael; Kolb, Tobias; Merklein, Marion (190, 2018)
Current trends in the industry go towards individualised parts in high volume production. Facing the high amount of different parts, efficient processes with a high flexibility are necessary. Within this context, laser-based additive manufacturing of metal parts become more important. These processes enable the production of individual geometries using a variety of metal materials. However, main challenges of this technology are rough surfaces, limited geometric precision and varying material properties. Therefore machining after the additive manufacturing process is a common approach for improving surface quality and geometric accuracy. However, the machining process affects the grain structure at the edges of the part. Using forming instead leads to a deformation of the grains but does not create new interfaces. Furthermore, the material properties can be improved due to work hardening and fibre flow. Within this work, a bulk metal forming process of an additively manufactured element of stainless steel 316L will be analysed. The aim of the investigation is a fundamental understanding of the forming behaviour and the material flow of an additively built metal part compared to the conventionally manufactured material. Therefore mechanical properties of both materials will be identified by upsetting tests. Additionally, fibre flow and Vickers hardness before and after the forming operation are analysed. It is detected that the forming behaviour of the additively manufactured material is strongly influenced by the layer-wise building process.<br

Bulk Microforming from Sheet Metal—A Promising Approach for the Mass Production of Cold-Formed Metallic Micro Parts - Kraus, Martin; Merklein, Marion (Minerals, Metals and Materials Series, 2021)
Every year billions of micro parts are produced. In mass production, cold bulk forming offers considerable technological, economical, and ecological potentials compared to alternative production methods. Due to the occurrence of scale effects, high tool stresses, and handling problems, cold bulk forming is not used for the mass production of multi-stage formed metallic micro parts. Within this paper, multi-stage bulk microforming from sheet metal is investigated on the laboratory scale with the material Cu-OFE. Throughout this process, the sheet metal strip serves both as a semi-finished product and as a handling aid. In the first forming stage, a pin is extruded from sheet metal, which is then extruded in a cup during the second stage. For the identification of size effects and the evaluation of such effects on the part quality, the tests are carried out on macro- and micro-scale. In the first step, the process-influencing variable of the blank holder pressure is investigated in the first forming stage in order to derive measures for the highest possible material utilization. The two-stage forming of the pin with cup is compared with a single-stage process to assess the part quality and material utilization depending on the process strategy. Using the correct geometric scaling, size effects are identified and their effects on the forming process are evaluated. The experimental results reveal that it is possible to fabricate micro parts with a diameter of 470 µm and a minimum wall thickness of 36 µm reproducible by using the presented cold bulk microforming process strategy.
CRIS-Team Scopus Importer:2021-09-03
Keywords: Bulk microforming; Material flow; Metallic micro parts; Pin extrusion; Sheet metal; Size effects

Bulk Microforming from Sheet Metal—A Promising Approach for the Mass Production of Cold-Formed Metallic Micro Parts - Kraus, Martin; Merklein, Marion (Proceedings of the 13th International Conference on the Technology of Plasticity, 2021)

Carburization behavior at elevated temperatures and mechanical properties of a hot stamped complex phase steel - Risse, Jan Henning; Sippel, Frank; Merklein, Marion (IOP Conference Series: Materials Science and Engineering, 2023)
As a lightweight construction strategy, hot stamped parts of ultra-high-strength steels with tailored properties are increasingly used for crash relevant components in car bodies, e.g., as B-pillars. With the process of tailored carburization, parts can be reinforced locally without increasing the sheet metal thickness. Thus, this process has the potential to be applied to lightweight components for no deformation zones, e.g., in the battery housings. Standardly, carburization is performed at 950 °C, with the highest strengths achieved at long times of up to 6 h, which prolongs the total process time. By raising the temperature, the carbon diffusion increases, which enables a reduced heat treatment time and, consequently, a shorter process time. Therefore, the objective of this study is to investigate the influence of elevated carburization temperatures on the mechanical properties of a carburized and hardened complex phase steel, CP-W® 800. A single carburization step at the enhanced temperatures leads to an embrittlement of the samples. Hence, an additional diffusion-annealing step is implemented to homogenize the carbon content, without enlarging the total heat treatment time. Depending on the time allocation of carburization and diffusion, the application of the diffusion annealing step results in higher strengths and ductility compared to only carburized samples.

Ceramic Adapted Tool Design in Cold Forging - Consideration of Thermal Effects on Prestressing System - Arbak, Murat; Engel, Ulf; Geiger, Manfred (4th International Conference and Exhibition on Design and Production of Machines and Dies/Molds, 2007)
LFT Import::2019-08-05 (1462)

Characterisation of a laser droplet formation process by acoustic emission - Govekar, E.; Klemencic, J.; Kokaja, T.; Jahrsdörfer, Bernd; Muzic, P.; Grabec, I. (Ultrasonics, 2004)
The aim of this article is to describe an application of acoustic emission to characterise a process of laser droplet formation from a metal wire. Laser droplet formation is a crucial process in new laser droplet welding technology, where parts are joined by means of the heat content of a liquid metal droplet deposited onto the parts to be joined. A laser beam is used for heating and melting the wire tip, and for detaching the molten pendant droplet. Depending on the process parameters, three different outcomes of the process can be observed: (1) no droplet formed; (2) a droplet formed but not detached; (3) a droplet formed and detached from the wire. It is shown that AE can be used to monitor the process and to indicate the different process outcomes. © 2004 Elsevier B.V. All rights reserved.
LFT Import::2019-07-16 (1088)
Keywords: Acoustic emission; Droplet detachment; Droplet formation; Laser beam

Characterisation of kinematic hardening and yield surface evolution from uniaxial to biaxial tension with continuous strain path change - Merklein, Marion; Suttner, Sebastian; Brosius, Alexander (CIRP Annals - Manufacturing Technology, 2014)
With respect to multistage forming processes the material behaviour and the history of the strain path during the process is of special interest for the improvement of the numerical prediction of forming processes. While different researchers investigated the Bauschinger effect during a load reversal and biaxial loading with pre-strained specimens, in this paper the yield locus evolution in the first quadrant of the principles stress space under biaxial loading of a modified cruciform specimen without test interruption is presented. The movement of the yield surface centre caused by kinematic hardening is approximated by an alternative approach based on experimental results. © 2014 CIRP.
LFT Import::2019-07-29 (2026)
Keywords: Kinematic hardening; Sheet metal; Stress

Characterisation of mechanical properties of laser welded tailored and patchwork blanks - Lamprecht, Klaus; Merklein, Marion (Proceedings of the 4th International Conference on Laser Assisted Net Shape Engineering, 2004)
LFT Import::2019-07-16 (1061)

Characterisation of new lubrication systems for hot forming of high strength aluminum alloys - Rigas, Nikolaos; Degner, Julia; Berendt, E.; Junker, F.; Merklein, Marion (OP Conference Series, Materials Science and Engineering, 2019)
LFT Import::2019-08-05 (2381)

Characterisation of strain rate dependency of sheet metals under biaxial loading with a strain rate controlled hydraulic bulge test - Lenzen, Matthias; Suttner, Sebastian; Merklein, Marion (7. WGP-Jahreskongress Aachen, 5.-6. Oktober 2017, 2017)
LFT Import::2019-08-05 (2247)

Characterisation of the flattening behaviour of idealised asperities - Weidel, Stephan; Engel, Ulf (Proceedings of the 11th International Conference on Metrology and Properties of Engineering Surfaces, 2007)
LFT Import::2019-08-05 (1417)

Characterisation of the flattening behaviour of modelled asperities - Weidel, Stephan; Engel, Ulf (Wear, 2009)
In metal-forming processes tribological conditions between tool and workpiece are of greatest importance for process quality and process feasibility. This is even truer for microforming applications, where at least two dimensions of the workpiece are in the sub-millimetre range, due to increasing friction when process dimensions are scaled down. This effect can be explained by the model of open and closed lubricant pockets characterising the workpiece surface and the invariance of topography to scaling. As the number of workpiece asperities contacting the tool is drastically reduced the flattening behaviour of single asperities is of major interest for characterising tribology in microforming processes in more detail. Especially, a topography emerging on top of flattened asperites, the so-called nanotopography and its impact on the friction conditions has to be considered. Modelled asperities represented by pyramids with a base area of 120 μm × 120 μm and a height of 32 μm are flattened with a high-resolution experimental setup which enables in situ observation of the contact area. In-process measurement is complemented by post-process analysing the topography by confocal microscopy and scanning probe microscopy. This paper will show that a nanotopography on top of flattened asperities can emerge under certain geometrical conditions and that it has an impact on the friction conditions in the tool/workpiece interface. The detailed knowledge about the evolution of surface topography is relevant in particular to microforming but also for an improved understanding of tribological phenomena in general. © 2008 Elsevier B.V. All rights reserved.
LFT Import::2019-07-29 (1542)
Keywords: Asperity; Metal forming; Surface characterisation; Tribology

Characterisation of the flow behavior of deep drawing steel grades in dependency of the stress state and its impact on FEA - Merklein, Marion; Sturm, Vera (International Journal of Material Forming, 2009)
In numerical simulation the flow behavior of the material is described by the flow curve under uniaxial stress condition. As within the tensile test experimental values can only be determined up to low strains, further experiments are applied in order to obtain higher strains. The alternative experiments are generally carried out under different stress conditions in comparison to the stress condition of the tensile test. Within this paper the differences in flow behavior under the respective stress conditions are figured out. Apart from the optical strain analysis of the tensile test after the onset of necking, the bulge test and the layer compression test are applied. Furthermore the work hardening of materials under different test conditions is compared. © Springer/ESAFORM 2009.
LFT Import::2019-07-29 (310)
Keywords: Deep drawing steel grades; Flow behavior; Stress condition

Characterisation of the flow properties of the quenchable ultra high strength steel 22MnB5 - Merklein, Marion; Lechler, Jürgen; Geiger, Manfred (Annals of the CIRP, 2006)
LFT Import::2019-08-05 (1268)

Characterisation of the Forming Behaviour of Patwork Blanks - Lamprecht, Klaus; Geiger, Manfred (Steel Research International, 2005)
LFT Import::2019-07-16 (1134)

Characterisation of the mechanical behaviour and the forming limits of metal foils using a pneumatic bulge test - Diehl, Alexander; Vierzigmann, Ulrich; Engel, Ulf (International Journal of Material Forming, 2009)
LFT Import::2019-07-29 (286)
Keywords: Forming limit diagram; Micro forming; Pneumatic bulge test

Characterisation of the Tensile Bonding Strength of Ti-6Al-4V Hybrid Parts Made by Sheet Metal Forming and Laser Beam Melting - Papke, Thomas; Huber, Florian; Geyer, Georg; Schmidt, Michael; Merklein, Marion (8th Congress of the German Academic Association for Production Technology (WGP), 2019)

Characterisation of the transition area at partial hot stamped car body components by the 3-point bending test - Hezler, Christian; Kopp, C.; Bader, M.; Griesbach, B.; Merklein, Marion; Russ, F. (Proceedings SCT2011, 2011)
LFT Import::2019-08-05 (1649)

Characterisation of Yielding BEhvior of Sheet Metal under Biaxial Stress Condition at Elevated Temperatures - Merklein, Marion; Hußnätter, Wolfgang; Geiger, Manfred (Annals of the CIRP, 2008)
LFT Import::2019-08-05 (1512)

Characterization and Description of Friction Conditions for Hot Stamping and Partial Hot Stamping of Ultra High Strength Steel - Schwingenschlögl, Patrik; Hildering, Sven; Merklein, Marion (Proceedings METEC & 2nd ESTAD, 2015)
LFT Import::2019-08-05 (2104)

Characterization and Modelling of Sheet Material with Graded Strength for More Accurate Finite Element Analysis - Lenzen, Matthias; Kraus, Martin; Merklein, Marion (Key Engineering Materials, 2022)
Many sheet materials do not exhibit constant properties over the sheet thickness. On the one hand, this can be caused by a rolling process with a pass reduction of 1-2%, the so-called skin pass rolling. This is mainly used for deep drawing steel grades to eliminate the pronounced yield strength of the base material. Another possibility is abrasive blasting or shot peening of sheet metal. This causes plastic deformation of the sheet surface and material strengthening. The grading can be used to locally strengthen components or locally adapt the roughness. Since many production processes today are designed numerically, the mapping of such a grading is necessary but currently not implemented in FE code. The aim of this research is, to correlate the material hardness to a plastic pre-strain with a newly developed characterization method. For this purpose, graded material properties are generated by means of abrasive blasting as an example process. The resulting locally varying work hardening over the sheet thickness is further integrated in finite element analysis by the assignment of a starting condition of a 2d-shell element formulation. With this approach, it is possible to map the graded material properties easily in FE simulations with a very good accuracy.
CRIS-Team Scopus Importer:2022-11-04
Keywords: abrasive blasting; Graded material properties; material modelling; sheet metal forming

Characterization of a magnetorheological fluid and simulative design of a magnetic field with respect to its suitability for hydroforming - Rösel, Sebastian; Merklein, Marion (Proceedings of the 5th International Conference on ADVANCES IN PRODUCTION ENGINEERING, 2010)
LFT Import::2019-08-05 (140)

Characterization of a Magnetorheological Fluid with Respect to its Suitability for Hydroforming - Rösel, Sebastian; Merklein, Marion (International Journal of Material Forming, 2010)
Nowadays the global warming and the shortage of resources represent big challenges. To cope with these deviances it is the duty of the automotive industry, to build up light weight constructions for high efficient vehicles. For example forming parts as components of exhaust systems or chassis components could be realized by hydroforming, a new flexible technology, which enables the realisation of undercuts and increases the forming limits. Thereby comparatively complex part geometries can be produced. Using this process the blank is deformed by gases or fluids as pressure media. In this case a magnetorheological fluid could be used. The key property of magnetorheological media is an increasing viscosity under magnetic fields. Thus they can not only serve as a pressure medium, but also act as a sealing in the flange area to prevent leakage. For a better understanding of the process a basic characterisation has to be done. Therefore an experimental setup is built up. Different parameters like feed rate and magnetic flux density are varied to get information about the behaviour of the tested fluid. The achievable cavity pressure is perhaps the most important parameter, because it determines the geometry of the part at the end of the forming step, especially at the small radii of the component. Another result of these tests is the fundamental potential of magnetorheological fluids for the process of hydroforming of blanks. © 2010 Springer-Verlag France.
LFT Import::2019-07-29 (137)
Keywords: Forming technology; Hydroforming; Magnetorheological fluid

Characterization of an additively manufactured coating using an upsetting test with miniaturized cylindrical specimen - März, Raphaela; Hetz, Peter; Bartels, Dominic; Schmidt, Michael; Merklein, Marion (Proceedings of the Institution of Mechanical Engineers Part L-Journal of Materials-Design and Applications, 2024)
In order to reduce CO2 emissions in production industry, the combination of several manufacturing processes is coming to the fore. One example is the combination of metal additive manufacturing with the forming technology, whereby the advantages of both process technologies can be used. The process combination can be applied to produce hybrid barrel sleeves, for example. Using a laser-based directed energy deposition (DED-LB/M), a circular coating is first applied to a blank, which is then deep-drawn in a second step. The additive layer serves as a wear-resistant coating. One way to increase process understanding for this process combination is numerical simulation. An important part of setting up the simulation model is characterizing the material in terms of its mechanical behavior. In order to avoid long building times, small sample geometries are suitable for characterizing the additive material. In the context of the paper, the upsetting test is therefore carried out with miniaturized specimens, whereby not only the base material Bainidur AM but also the addition of tungsten carbide microparticles and carbon nanoparticles is investigated. The in-situ modification of the material significantly increases the yield strength, but at the same time reduces the ductility. The microhardness of the material is also increased by the addition of carbon or tungsten carbid
Keywords: DED-LB/M; hybrid parts; material characterization

Characterization of damage and fracture of high strength steels within air bending - Kaupper, Markus; Tsoupis, Ioannis; Merklein, Marion; Weidinger, P. (Proc. 6th Int. Conf. and Exhibition on Design and Production of Machines and Dies/Molds, 2011)
LFT Import::2019-08-05 (1638)

Characterization of friction stir consolidated recycled billet by uniaxial compression tests with miniaturized cylindrical specimen - Latif, Abdul; Ingarao, Giuseppe; Fratini, Livan; Hetz, Peter; Merklein, Marion (Materials Research Proceedings, 2023)
Friction stir consolidation (FSC) is a solid-state recycling method that directly converts machining scraps into semifinished billets. This process has been proven to be a more energy efficient and environmentally friendly technique compared to remelting based conventional recycling methods. During FSC, machining chips are transformed into a solid billet by the stirring action and friction heat of the rotating tool. Due to process mechanics, especially temperature gradient and strain rate, billets have shown different hardness values and grain size distribution across their sections. Therefore, in this research, miniaturized upsetting samples are extracted from the FSC billet. The purpose of minimizing the sample size is to get the local properties of a particular position. The intensive characterization was performed with future goals to find a more accurate numerical modelling and ultimately assign FSC billet to a potential industrial application.
CRIS-Team Scopus Importer:2023-08-04
Keywords: Aluminum Alloys; Compression Test; Friction Stir Consolidation; Recycling

Characterization of Heat Transfer Coefficients of Tool Materials and Tool Coatings for Hot Stamping of Boron-Manganese Steels - Wieland, Michael; Merklein, Marion (Key Engineering Materials, 2010)
LFT Import::2019-07-29 (1017)
Keywords: Heat transfer coefficient; Hot stamping; Tool coating

Characterization of hybrid components consisting of SEBM additive structures and sheet metal of alloy Ti-6Al-4V - Schaub, Adam; Jüchter, Vera; Singer, Robert; Merklein, Marion (Key Engineering Materials, 2014)
Within this paper the characterization of hybrid components consisting of selective electron beam melting (SEBM) additive structures and sheet metal of alloy Ti-6Al-4V will be presented. Key idea of the new production approach is the combination of the advantages of two different manufacturing processes. On the one hand the very high flexibility of the additive manufacturing process and on the other hand the economic production of conventional geometries by deep drawing operations. Main challenge within this new and innovative process is the identification and quality of the properties of the new hybrid components after the manufacturing process. The necessary evaluation consists of three parts: the analysis of the deep drawing blanks, the additive manufactured structure and finally the connection between both. Whereas standardized testing methods are available for the testing of the blanks and the additive structure, there are hardly scientific publication which deals with the investigation of the connection between them. Therefore, a new testing methods and consequently a new tool design was developed in order analyze the specimens in dependency of different strain- and stress conditions. At the end microstructural investigations were performed to identify the fundamental mechanisms which lead to the different properties on macroscopic scale. The result proofed that in particular the electron beam power has a high influence on the production process and thereby the connection quality. © 2014 Trans Tech Publications, Switzerland.
Keywords: Additive manufacturing; Selective electron beam melting; Sheet metal; Ti-6Al-4V

Characterization of kinematic hardening with a hydraulic bulge test - Lenzen, Matthias; Schmid, Harald; Merklein, Marion (Procedia Manufacturing, Special Issue, 2020)

Characterization of material behaviour under pure shear condition - Hußnätter, Wolfgang; Merklein, Marion (Proceedings of ESAFORM 2008, 2008)
In the last decades the design of sheet metal manufacturing processes and products has been mainly influenced by modern tools, e. g. the large field of numerical simulations based on the finite element (FE-) method. Since the modeling of the material behavior is essential for the quality of the calculated results both the determination of characteristic material data and the transformation of these into material models are of high relevance for the whole process-chain. New materials, e. g. light weight sheet metals often show anisotropic and sometimes also some special forming behavior like the twinning effect of magnesium alloys. Furthermore, car body components become more and more complex concerning the geometry and that leads to a mixture of different stress conditions during forming, e. g. deep drawing, stretching and shearing. As a consequence of these reasons also the material models have to be enhanced and therefore especially the yield locus diagram and the real stress-strain curve must include the relevant material characteristics and data. Nevertheless, the forming behavior of sheet metal under pure shearing condition is not sufficient described. In 1984 Miyauchi proposed a new kind of shear test that is characterized by a symmetrical loading of the specimen and homogenous areas of shearing. In this paper a new tool and a new specimen's geometry are introduced with which shear tests have been done in the style of Miyauchi for different materials. The forming behavior is analyzed using an optical strain measurement system, in order to obtain detailed information on the onset of plastification as well as the homogeneity of the plastification itself. It can be shown that the two shear zones are constant and homogenous during the forming process. Basing on the experimental investigations the real stress-strain curves and the yield loci under pure shear conditions are obtained. © Springer/ESAFORM 2008.
LFT Import::2019-08-05 (1511)
Keywords: Anisotropy; Material characterization; Shear Test; Yield Loci; Yielding

Characterization of mechanical properties in processed friction stir welded high-strength aluminum alloy blanks - Gnibl, Tobias; Merklein, Marion (Procedia Engineering, 2014)
LFT Import::2019-07-29 (2034)
Keywords: Material characterization; Recrystallization; Rolling

Characterization of sheet metal components by using an upsetting test with miniaturized cylindrical specimen - Hetz, Peter; Kraus, Martin; Merklein, Marion (CIRP Annals - Manufacturing Technology, 2022)
Especially for safety-relevant components local characterization of the mechanical properties is necessary for product testing. For sheet metal parts with a complicated geometry conventional specimens for standardized tests cannot be extracted due to size limitations. Thus, a novel extraction procedure of miniaturized upsetting specimens is investigated. Taking a miniaturized upsetting specimen out of the sheet component allows for the first time the characterization of sheet metals in a standardized upsetting test under uniaxial compression stresses. Furthermore, this enables the analysis of strain hardening behavior of components and a direct validation of finite element simulations based on the true stress.
CRIS-Team Scopus Importer:2022-08-12
Keywords: Material characterization; Metal forming; Wire EDM

Characterization of temperature-dependent tension-compression asymmetry for high-strength aluminium alloys - Hetz, Peter; Merklein, Marion (Production at the leading edge of technology. Proceedings of the 9th Congress of the German Academic Association for Production Technology (WGP), 2019)
In the course of lightweight construction, modern materials with high strength and low density are essential. High-strength aluminium alloys such as 7000 series aluminium alloys meet these requirements but are only limited formable at room temperature. Thus, different heat assisted sheet metal forming processes are used to increase the formability. First investigations on the highstrength aluminium alloy AA7075 show a temperature-dependent and tensilecompressive asymmetric material behaviour. Since both tensile and compressive forces occur in sheet metal forming processes, an understanding of temperaturedependent tension-compression asymmetry is vital to set up material models for process design. Until now, the tension-compression asymmetry has barely been investigated for high-strength aluminium alloys at different temperatures. Therefore, further experimental studies are necessary. Within this contribution, the material behaviour of AA7020-T6 and AA7075-T6 is hence examined under uniaxial tensile and compressive load at different temperatures. For this purpose, both tensile and compressive tests are carried out on flat specimens between room temperature and 200 °C.<br
Keywords: Tension-compression asymmetry; High-strength aluminium alloy; Warm forming

Characterization of the Bauschinger effect and identification of the kinematic Chaboche model by tension-compression tests and cyclic shear tests - Suttner, Sebastian; Merklein, Marion (Proc. International Deep Drawing Research Group Conf. IDDRG 2014, 2014)
LFT Import::2019-08-05 (2025)

Characterization of the shear stress state under non-proportional strain paths realized by biaxial stretching in the Marciniak Test - Suttner, Sebastian; Merklein, Marion (Materials Today: Proceedings, 2015)
Complex parts with sharp corners are on the rise to satisfy increasing customer demands on the design. To realize these parts in single or multistage forming processes the information of the material behavior under linear and non-linear strain paths is essential. As Bauschinger already showed for the material behavior under cyclic loading, a reduction of the subsequent beginning of plastic yielding can be observed. Different research works studied the Bauschinger effect under cyclic proportional loading or non-proportional strain paths mostly with uniaxial pre-straining of the material. In this paper the material behavior under shearing after previous biaxial stretching in the Marciniak test is analyzed for the aluminum alloy AA5182 and the advanced high strength steel DP600. The Marciniak test is suited for biaxial pre-straining due to an almost almost equibiaxial strain state and a homogeneous strain distribution in-plane on the bottom of the specimen up to higher strains than in a biaxial tensile test. The subsequent shear test is realized with a modified shear test specimen according to the ASTM standard. Finally, the influence of biaxal pre-straining on the beginning of plastic yielding under shear condition, the hardening behavior and the maximum reachable shear strain is investigated for a better understanding of the material behavior under non-proportional loading paths.
LFT Import::2019-07-29 (2101)
Keywords: Bauschinger effect; Material characterization; Non-linear strain paths

Characterization of the Tribological Behavior of Different Tool Coatings and Dry Lubricant for High-Strength Aluminum Alloys at Elevated Temperatures - Rigas, Nikolaos; Merklein, Marion (Advanced Engineering Materials, 2023)
Keywords: high-strength aluminum; wear; tool coatings; hot form quench

Characterization of tribological and thermal properties of metallic coatings for hot stamping boron-manganese steels - Merklein, Marion; Lechler, Jürgen; Stöhr, Thomas (Tagungsband The Coatings, 2008)
LFT Import::2019-08-05 (194)

Characterization of tribological conditions within direct hot stamping - Schwingenschlögl, Patrik; Merklein, Marion (Journal of Materials Processing Technology, 2020)
The aim of this study is to create a detailed process understanding regarding the tribological conditions within direct hot stamping. Hot stamping has established as a common technology for manufacturing safety-relevant components in modern car bodies. However, due to the high forming temperatures within hot stamping applications, no suitable lubricants have been developed yet. As a consequence, high friction and severe wear occur during the forming. This affects the tool wear as well as the resulting part quality. For improving the robustness and the efficiency of industrial hot stamping processes, future measures to reduce the tribological loads have to be found. The key to the development of such measures is a detailed process understanding of the tribological conditions. Within this study, friction and wear are analyzed for different workpiece and tool temperatures, relative velocities and contact pressures. Based on the experimental results, detailed knowledge of the critical cause-effect relations between process parameters and tribological behavior is acquired. The friction behavior is analyzed via strip drawing experiments under hot stamping conditions. The amount of wear is determined via confocal microscopy measurements before and after the experiments. The results of this study help to improve the process understanding of the tribological conditions within the hot stamping process and to develop future measures for reducing tool wear.
CRIS-Team Scopus Importer:2019-12-17
Keywords: 22MnB5; AlSi; Friction; Hot stamping; Strip drawing test; Wear

Characterization of Work Hardening Behavior of Additively Manufactured Stainless Steel 316L (1.4404) Using Bulk Metal Forming at Elevated Temperature. - Papke, Thomas; Merklein, Marion (Lasers in Manufacturing Conference 2019, 2019)

Characterization of yielding and hardening of AA6016 - Hußnätter, Wolfgang; Merklein, Marion (Proceedings of IDDRG Conference, 2006)
LFT Import::2019-08-05 (1276)

Characterization of Yielding Magnesium Alloy AZ31 with BBC2005 - Hußnätter, Wolfgang; Banabic, D.; Merklein, Marion; Geiger, Manfred (Proceedings of ICTP2008, 2008)
The finite element analysis (FEA) is getting more and more important in fields of sheet metal forming for process design and parts' dimensioning. But the reliability and the quality of the numerical results strongly depend on the model that has to be built for the calculations. Especially the modelling of the elastic-plastic material behaviour is of main importance, since it shows a wide impact on the numerically calculated stresses and strains in sheet metal parts. Therefore, the material data have to be determined using experiments and have to be modelled basing on the experimental results. Most of semi-finished products are characterized by anisotropic material properties which can be approximated by yield criteria like those of Hill'48 for common steels or Barlat'89 and various BBC-models for some aluminium alloys. The diversity of new materials, in particular light weight materials like magnesium sheet metals may cause the necessity of new yield criteria, but in some cases the material behaviour can also be modelled by existing ones. In this paper the material behaviour of the magnesium alloy AZ31 under plane tensile stress conditions is investigated. The experimental investigations have been done at the Chair of Manufacturing Technology (LFT) of the University of Erlangen using a novel experimental setup. The yielding behaviour is determined basing exclusively on real material data out of experiments so that no FE-calculations are necessary to detect strains and stresses. Using these data different yield criteria are applied to model the real material characteristics, whereas the criterion of BBC2005 gives to the best approximation for uniaxial yield stresses, the anisotropy coefficients and also the yield locus diagram.
LFT Import::2019-08-05 (1514)

Characterization of yielding of sheet metal at elevated temperatures - Hußnätter, Wolfgang; Merklein, Marion; Geiger, Manfred (Journal of Materials Processing Technology, 2007)
In times of highest significance of process modeling and numerical simulation characterization of material properties is of special importance for components' and tools' dimensioning. Especially in fields of sheet metal forming the mechanical behavior of components highly differ according to real stress condition. In particular yield loci combine the information of beginning of yielding with biaxial stress conditions. Although these data are essential, they are unknown for many different sheet metals, mainly new materials used for light-weight constructions, e.g. aluminum and magnesium alloys. In this paper investigations done on a novel concept of experimental setup, which has been developed at the Chair of Manufacturing Technology (LFT) and which enables the determination of yield loci at elevated temperatures, are presented. The strategy for local heating is based on FE-calculations and verified afterwards. A 210 W-diode laser is used for the local heating of the specimens up to temperatures in the range of 300 °C. During forming process a constant temperature is guaranteed by a closed-loop temperature-control (CLTC), the homogeneous distribution of temperature in the forming zone is realized using a special optical system. © 2007 Elsevier B.V. All rights reserved.
LFT Import::2019-07-16 (1381)
Keywords: Diode laser; FE-simulation; Materials' characterization; Yield locus

Charakterisierung der Fließeigenschaften von Aluminium- und Magnesiumblechwerkstoffen - Geiger, Manfred; Merklein, Marion; Hußnätter, Wolfgang (Tagungsband 12. Sächsische Fachtagung Umformtechnik (SFU) - Leichtbau durch Umformtechnik, 2005)
LFT Import::2019-08-05 (1192)

Charakterisierung der Umformbarkeit und mechanischen Eigenschaften von additiv gefertigtem Ti6Al4V - Papke, Thomas; Huber, F.; Heimes, M.; Schmidt, M.; Merklein, Marion (XXXVIII. Verformungskundliches Kolloquium, 2019)
LFT Import::2019-08-05 (2359)

Charakterisierung der Umformeigenschaften von Blechwerkstoffen - Trends und Möglichkeiten der Prüftechnik - Merklein, Marion; Hußnätter, Wolfgang; Staud, Detlev; Kuppert, Andreas (Tagungsband Werkstoffprüfung 2007, 2007)
LFT Import::2019-08-05 (289)

Charakterisierung des Formänderungsvermögens von hoch- und höchstfesten Karosseriestählen mit dem 3-Punkt Biegeversuch - Einfluss der Probenpräparation - Kopp C.; Schaller L.; Jessen, B.; Merklein, Marion; Hezler, Christian (Tagungsband Werkstoffprüfung 2009, 2009)
LFT Import::2019-08-05 (253)

Charakterisierung des Umformverhaltens von Magnesiumblechen bei erhöhter Temperatur - Hecht, Joachim; Merklein, Marion (Tagungsband XXIV. Verformungskundliches Kolloquium, 2005)
LFT Import::2019-08-05 (1252)

Charakterisierung des Verfestigungsverhaltens der Magnesiumlegierung AZ31 im Scherspannungszustand bei erhöhter Temperatur - Suttner, Sebastian; Merklein, Marion (Tagung Werkstoffprüfung 2015, 2015)
LFT Import::2019-08-05 (2124)

Charakterisierung des Versagens von hochfesten, mehrphasigen Stahlwerkstoffen in Abhängigkeit der Dehnungshistorie - Merklein, Marion; Lechler, Jürgen; Lupino, Roberto (Tagungsband Werkstoffprüfung, 2009)
LFT Import::2019-08-05 (717)

Charakterisierung einer magnetorheologischen Flüssigkeit für die Innenhochdruck-Umformung von Rohren - Dal Bò, Paolo; Blankl, Andreas; Geiger, Manfred (Tagungsband der Femlab Konferenz: Neue Wege der Multiphysik-Simulation, 2005)
LFT Import::2019-08-05 (1248)

Charakterisierung und Modellierung des Fließverhaltens höchstfester Vergütungsstähle bei erhöhten Temperaturen - Merklein, Marion; Lechler, Jürgen; Geiger, Manfred (Umformtechnik im Spannungsfeld zwischen Plastomechanik und Werkstofftechnik, 2008)
LFT Import::2019-07-29 (1560)

Charakterisierung und Modellierung des spannungszustandsabhängigen Werkstoffverhaltens der Magnesiumlegierung AZ31B für die numerische Prozessauslegung - Suttner, Sebastian (Friedrich-Alexander-Universität Erlangen-Nürnberg, 2017)
The use of light-weight materials, such as magnesium alloys, offers great potential in the area of sheet metal forming. In addition, the complex material behavior is to be modeled exactly in the process design. In the scope of the work, the stress statedependent material behavior of the magnesium alloy AZ31 B was investigated to improve the prediction accuracy of sheet metal forming processes. The focus of the investigations was the development, verification and validation of a novel material model for the consideration of anisotropic hardening at a forming temperature of 200° C. In order to determine the material characteristic under stretch forming, an innovative hydraulic bulge test (HB V) with online strain rate control by means of an optical strain measurement system was implemente

Charakterisierung von lasererzeugten Mikrostrukturen - Popp, Uwe; Weidel, Stephan; Engel, Ulf (LEF 2003, Laser in der Elektronikproduktion & Feinwerktechnik - Tagungsband des 8. Erlanger Seminars LEF (2003), 2005)
LFT Import::2019-08-05 (1168)

Classification Problems in Manufacturing of Sheet Metal Parts - Geiger, Manfred; Greska, Wolfgang; Franke, Volker (Reprints of the 2nd International Workshop on Learning in Intelligent Manufacturing Systems, 1995)
LFT Import::2019-08-05 (542)

Clinching of Aluminum Materials – Methods for the Continuous Characterization of Process, Microstructure and Properties - Kupfer, Robert; Köhler, Daniel; Römisch, David; Wituschek, Simon; Ewenz, Lars; Kalich, Jan; Weiß, Deborah; Sadeghian, Behdad; Busch, Matthias; Krüger, Jan; Neuser, Moritz; Grydin, Olexandr; et al. (Journal of Advanced Joining Processes, 2022)
Clinching as a mechanical joining technique allows a fast and reliable joining of metal sheets in large-scale production. An efficient design and dimensioning of clinched joints requires a holistic understanding of the material, the joining process and the resulting properties of the joint. In this paper, the process chain for clinching metal sheets is described and experimental techniques are proposed to analyze the process-microstructure-property relationships from the sheet metal to the joined structure. At the example of clinching aluminum EN AW 6014, characterization methods are applied and discussed for the following characteristics: the mechanical properties of the sheet materials, the tribological behavior in the joining system, the joining process and the resulting material structure, the load-bearing behavior of the joint, the damage and degradation as well as the service life and crack growth behavior. The compilation of the characterization methods gives an overview on the advantages and weaknesses of the methods and the multiple interactions of material, process and properties during clinching. In addition, the results of the analyses on EN AW 6014 can be applied for parameterization and validation of simulations.<br
Keywords: Mechanical joining; Clinching; Aluminum; Characterization methods; Process-structure-property relationships

Closed Loop Control of Laser Beam Welding - Otto, Andreas; Hohenstein, Ralph; Dietrich, Simon (Proceedings of the XIV. International Symposium on Gas Flow and Chemical Lasers & High Power Laser Conference, 2007)
A closed loop control for the laser beam welding process requires the collection of process parameters relevant for the machining result by means of suitable sensors, the identification of the control path as well as the feedback of the acquired data via a control algorithm and suitable actors into the process. The present paper describes such a control with the sensors respectively actors used and shows first results of controlled laser beam welding.
LFT Import::2019-08-05 (1386)
Keywords: Actors; Closed loop control; Laser beam welding; Laser material processing; Quality control; Sensors

Closed-Loop-Control of the Focus-Parameters of rf-Excited CO2 High Power Lasers. - Kauf, Michael; Schuberth, Stefan; Hutfless, Joachim; Geiger, Manfred (Tagungsband zu Mechanik und Optik - Hochleistungslaser im Maschinenbau, 1995)
LFT Import::2019-08-05 (571)

CO2-Laser Cutting Fiber Reinforced Plastics - Müller, Roland; Nuss, Rudolf; Geiger, Manfred (Tagungsband Congress on Optical Science and Engineering (ECO2): High Power Lasers and Laser Machining Technology, 1989)
LFT Import::2019-08-05 (437)

CO2-Laserstrahlschneiden kurzglasverstärkter Verbundwerkstoffe - Müller, Roland (Friedrich-Alexander-Universität Erlangen-Nürnberg, 1992)
Im Rahmen dieser Arbeit wurden der Schneidprozess, die Vorgänge in der Schnittfuge sowie die erzielbare Bearbeitungsqualität beim Laserstrahlschneiden von kurzglasverstärkten Verbundwerkstoffen eingehend untersucht. Der Schwerpunkt lag bei umfangreichen technologischen Schneidversuchen im Hinblick auf das Erzielen optimaler Bearbeitungsqualität. Dabei wurden die Einflüsse maßgeblicher Prozessparameter auf die Feingestaltabweichung der Schnittfläche, die Schnittfugengeometrie, sowie die Maß- und Formabweichung ausgewählter Prüfgeometrien bestimmt. Aus diesen Ergebnissen wurden Kennfelder für die erzielbare Bearbeitungsqualität erstellt, die in ihrer Tendenz allgemeingültig sind und sich qualitativ auf andere CO2-Laserstrahlwerkzeugmaschinen übertragen lassen. Das so gewonnene grundlegende Verständnis über die Veränderung der Bearbeitungsqualität bei gleichzeitiger Variation mehrerer Prozessparameter ermöglicht das rasche Abschätzen der Grenzen des Schneidprozesses sowie das schnelle Auffinden optimaler Schneidparameterbereiche. Für das Laserstrahlschneiden von kurzglasverstärkten Verbundwerkstoffen wurde ein analytisches Abtragsmodell entwickelt, mit dessen Hilfe sich das Bearbeitungsergebnis auf eine Genauigkeit von ca. 6% vorausberechnen läss

Cold forging of closely-tolerated functional components out of blanks – possibilities of the new process class sheet-bulk metal forming - Koch, Johannes Peter Karl; Merklein, Marion (Proc. 6th JSTP Int. Seminar Precision Forging, 2013)
LFT Import::2019-08-05 (1903)

Combination of laser beam cutting and welding for car body manufacturing: welding with wire as filler - Geiger, Manfred; Hoffmann, Peter; Deinzer, Günter (Proceedings of the 3rd European Conference on Laser Treatment of Materials (ECLAT), Erlangen, 1990)
LFT Import::2019-08-05 (731)

Combination of versatile self-piercing riveting processes - Wituschek, Simon; Kappe, Fabian; Meschut, Gerson; Lechner, Michael (Materials Research Proceedings, 2023)

Combined tube and double sheet hydroforming for the manufacturing of complex parts - Merklein, Marion; Geiger, Manfred; Celeghini, Martino (Annals of the CIRP 2005, 2005)
LFT Import::2019-08-05 (1222)
Keywords: Hydroforming; Sheet metal; Tube

Comparative study of two different laser forming mechanisms regarding the mechanical properties of aluminium alloys - Merklein, Marion; Geiger, Manfred (Laser Assisted Net shape Engineering (LANE), 2001)
LFT Import::2019-07-15 (872)

Comparison between Laser Sintering of PEEK and PA using Design of Experiment Methods - Rechtenwald, T.; Eßer, Gerd; Schmidt, Michael; Pohle, D. (Proceedings of the 3rd International WLT-conference on Lasers in Manufacturing, 2005)
PEEK (Polyetheretherketone) as well as Polyamide - the standard laser sintering material - are both semi-crystalline thermoplastics. Moreover, PEEK offers outstanding temperature resistance, mechanical strength and stiffness. PEEK possesses an outstanding chemical resistance, which leads to an excellent biocompatibility making the material a good choice especially for the manufacturing of medical instruments or even implants. Up to now these parts typically are produced by conventional manufacturing methods like injection moulding. But especially the production of individually shaped parts like implants would benefit a lot from a more flexible manufacturing technique. Laser Sintering (LS) can offer the required flexibility. Moreover, it is the most promising Rapid Prototyping Technology for the production of thermoplastic parts with a good geometrical accuracy on one hand and satisfying mechanical properties on the other. LS consequently is the ideal production technology for individual parts. It enables the direct manufacturing of products with complex geometries, including undercuts and defined porosity. Due to its high melting temperature of about 343°C laser sintering PEEK is a challenge compared to the standard polymer polyamide with a moderate melting point of about 172°C. This paper describes results on selective laser sintering of PEEK in comparison to laser sintering of the standard polymer, polyamide, using paired comparison and a full factorial design. The investigated influence coefficients on the process include the operating parameters of the laser system, the properties of the applied PEEK powder and the preheating temperature of the powder bed. Their effects on the sintering results are described and discussed in detail. © 2005 Taylor & Francis Group.
LFT Import::2019-08-05 (1196)

Comparison of different forming methods on deep drawing and springback behavior of high-strength aluminum alloys - Rigas, Nikolaos; Schmid, Harald; Merklein, Marion (INTERNATIONAL DEEP-DRAWING RESEARCH GROUP CONFERENCE (IDDRG 2021), 2021)
High-strength aluminum alloys of the 7XXX series have a high potential for safety and crash-relevant components due to their advantageous density-to-strength ratio. Currently, the use of these alloys is limited because of the low formability at room temperature. By using thermal supported forming strategies, failure-free deep drawing is possible for these materials. At present, several thermal-assisted forming processes exist, but so far there is no comparison between these forming operations. For this purpose, this study compares the deep drawing behavior of the alloy AA7075 by using different thermally-assisted forming operations. Aim of this work is to enhance the understanding and comparability between different thermally-assisted forming processes for high-strength aluminum alloys. First, a thermal simulator is used to investigate the mechanical material behavior according to different temperature-time curves by using uniaxial tensile tests. Subsequently, the formability and springback behavior is determined numerically and experimentally in a model test. Finally, for one thermally assisted forming method, the experiments are scaled up to a real size process with drawbeads to validate the transferability. This study can help to improve the scientific knowledge for the use of these materials in future.<br
CRIS-Team WoS Importer:2021-11-05
Keywords: High Strength Aluminum; Drawbead; Springback; Finite Element Simulation

Comparison of extrusion processes in sheet-bulk metal forming for production of filigree functional elements - Pilz, Florian; Merklein, Marion (CIRP Journal of Manufacturing Science and Technology, 2019)
Increasing demands on forming processes with regard to the functional integration of components and lightweight construction pose a challenge to conventional processes. The application of bulk forming operations on sheet metal semi-finished products, also called sheet-bulk metal forming (SBMF), is a suitable approach to meet these challenges. Insufficient die filling and high tool loads are limiting factors in SBMF processes. In order to overcome these limitations in the future, it is necessary to provide appropriate measures. The basis for this is a comprehensive understanding of the manufacturing process for lock and gear toothing by extrusion on sheet metal. This paper identifies requirements for extrusion processes and establishes two corresponding processes. In addition to carrying out experimental investigations, numerical models are developed and validated with the aid of forming tests. In combination with experimental analysis, the simulation models are then used to investigate similarities and differences between both processes. During the processing of the steel 1.0338 (DC04), the investigations showcase a process class specific material flow, demanding tool loads and challenges in the production of filigree functional elements.
CRIS-Team Scopus Importer:2019-07-19
Keywords: Extrusion; Process design; Sheet forming; Sheet-bulk metal forming; Simulation; Tool load

Comparison of forming processes for micro textured cups - Reck, Manuel; Merklein, Marion (51st SME North American Manufacturing Research Conference, 2023)

Comparison of forming processes for micro textured cups - Reck, Manuel; Merklein, Marion (Manufacturing Letters, 2023)
Friction losses are present in all kinds of technical systems. This is always associated with additional energy consumption, which can be partly avoided as it arises. Energy savings can be achieved by a wide range of approaches. The application of friction reducing coatings on bodies in relative motion is widespread. The coating of parts is however only suitable to a limited extent for the production in large batches. Therefore, research approaches consider alternative methods to achieve friction reductions. A promising approach is the integration of miniaturized pockets on the surface of the component. In lubricated contacts, the lubricant can then accumulate in these indentations. The relative motion between two bodies thus builds up a hydrodynamic pressure and consequently reduces friction. Forming technology is suitable for the efficient production of metallic components in large quantities. The aim of this study is therefore to identify challenges in the integration of micro coining in established forming processes. Two processes from sheet metal forming and bulk metal forming are investigated. In a combined experimental and numerical approach, process-specific challenges are derived regarding the texturing process and the numerical process modelling for combined micro coining. The analysis is carried out on a cup geometry, as used in the automotive sector as tappets in the valve train. The case hardening steel 16MnCr5 (1.7131) is used as workpiece material.
CRIS-Team Scopus Importer:2023-10-20
Keywords: Extrusion; Modelling; Sheet metal; Texture

Comparison of new analytical an numerical approaches to model the three-roll-push-bending process - Plettke, Raoul; Vatter, Peter (International Journal of Mechatronics and Manufacturing Systems, 2014)
Freeform bent tubes can be produced with the highly flexible three-roll-push-bending. The process has been fundamentally investigated in recent research by numerical simulation using shell or volume elements. However, because of the large aspect ratio of tube length to wall thickness, computation time required is high. This prohibits the integration in analysis routines to predict the resulting geometry online. In this contribution, the basics of two new approaches are presented to compute the resulting bending radius of two-dimensional freeform bends requiring significantly less computation time. The first approach is based on an analytically derived moment-curvature relationship considering realistic flow behaviour. In the second one, a numerical method is developed using beam elements. The results are compared to experimental data and to numerical results using shell elements for steel and aluminium tubes.
LFT Import::2019-07-29 (1967)
Keywords: Aluminium tubes; Beam elements; Bending theory; Finite-element-model; Flexible manufacturing system; Freeform bending; Modelling; Shell elements; Steel tubes; Three-roll-push-bending; Tube bending

Comparison of numerical simulation and measurement of shear test and uniaxial compression test to verify material model for granular material used as medium for hydroforming - Grüner, Martin; Merklein, Marion (Proc. 5th International Conference on Advances in Production Engineering, 2010)
LFT Import::2019-08-05 (494)

Comparison of process characteristics and resulting microstructures of maraging steel 1.2709 in Additive Manufacturing via Laser Metal Deposition and Laser Beam Melting in Powder Bed - Karg, Michael; Hentschel, Oliver; Ahuja, Bhrigu; Junker, Daniel; Haßler, Ulf; Schäperkötter, Claus; Haimerl, Andreas; Arnet, Horst; Merklein, Marion; Schmidt, Michael (6th International Conference on Additive Technologies, 2016)
Laser Metal Deposition (LMD) with Blown Powder and Laser Beam Melting (LBM) in Powder Bed are two Additive Manufacturing technologies that can produce high-quality metal parts in principle. Both technologies are based on melting of fine metal powders employing highintensity laser radiation. Apart from the obvious differences defined by system technology, LMD and LBM differ largely in fundamental boundary conditions of laser-materialinteraction. Process conditions in LMD and LBM and corresponding microstructures were compared on the example of martensitic aging steel 1.2709. This material has been one of the most popular ones in industrial use with LBM for about a decade, typically processed with laser powers below 400 W in continuous wave (cw) mode. With LMD, 1.2709 has not been commonly used so far. LMD typically engages higher cw laser powers of around 1000 W, larger laser spot diameters and smaller feed rates than LBM. Increased laser power kindles hopes for increased productivity, which is a key factor for economic viability. For a more comprehensive comparison, 1.2709 processed by LBM with 1000 W was also considered. Samples were analyzed metallographically, by computed x-ray tomography, hardness testing before and after heat treatment. Chemical compositions of powder and built samples were compared.
Keywords: Maraging Steel; 1.2709; microstructure; Laser Beam Melting; Laser Metal Deposition

Comparison of Strain-path Indicators for Analysis of Processes in Sheet-bulk Metal Forming - Gutknecht, Florian; Vogel, Manfred; Schulte, Robert Karl; Merklein, Marion; Rosenbusch, Daniel; Koch, Sergej; Hübner, Sven; Behrens, Bernd Arno; Tekkaya, Erman; Clausmeyer, Till (The 13th International Conference on Numerical Methods in Industrial Forming Processes, 2019)

Component residual stress control in forward rod extrusion by material flow and tribology—experiments and modeling - Jobst, Andreas; Floros, Dimosthenis; Steinmann, Paul; Merklein, Marion (Forschung Im Ingenieurwesen-Engineering Research, 2021)
The forward rod extrusion of ferritic stainless steel X6Cr17 (DIN 1.4016) is here investigated with the objectives to experimentally identify and numerically verify the effect of the lubrication system and die opening angle on residual stresses. Three lubricants – MoS2, soap and polymer – are considered whose tribological properties are characterized via double cup extrusion tests. The effect of material flow is also studied by forming in conical dies featuring three different opening angles. The extrusion experiments revealed a decrease in the near-surface tensile stresses with decreasing friction for all the considered opening angles. An opening angle of 2α = 90° led to the highest tensile residual stresses. Both an increase to 2α = 120° and a decrease to 60° resulted in reduced tensile stresses and even a shift to compressive stresses. Furthermore, a previously developed numerical model of forward rod extrusion is optimized and validated against the experimentally measured residual stresses. The effect of the spatial and temporal discretizations of the model on the predicted residual stresses is investigated. Based on the experimental and numerically verified results, the recommendation to reduce friction in forward rod extrusion is derived as a means to obtain a less detrimental to the lifecycle of extruded parts residual stress state.

Comprehensive approach for process modeling and optimization in cold forging considering interactions between process, tool and press - Kroiss, Thomas; Engel, Ulf; Merklein, Marion (Journal of Materials Processing Technology, 2012)
LFT Import::2019-07-29 (1847)

Comprehensive material characterization for an intermediate heat treatment - Lechner, Michael; Kuppert, Andreas; Merklein, Marion (Key Engineering Materials, 2013)
Encouraged by increasing climate regulations there is a trend to lightweight constructions in the transportation sector, particularly in the automotive industry. An auspicious possibility to reduce the weight of the vehicle is the substitution of conventional steel by aluminum alloys. However, aluminum has a low formability and therefore new technologies have to be found in order to enhance the materials spectrum of application. A new strategy to extend the process limit is the short-term aluminum intermediate heat treatment between two forming operations. Key idea is the partial adaption of the mechanical properties with a short term heat treatment. By the interaction of soft and hard areas the material flow during the forming operation can be improved and the formability can be enhanced. Prerequisite for a successful application of the technology and the numerical simulation is a comprehensive knowledge about the interaction of pre-straining and a subsequent short term heat treatment. Within this paper the mechanical properties in dependency of the two parameters will be presented and a process window for the heat treatment after first forming operations will be derived. Moreover, the influence of batch fluctuations and the impact of ageing will be demonstrated. © (2013) Trans Tech Publications.
LFT Import::2019-07-29 (1855)
Keywords: Intermediate heat treatment; Material characterization; Precipitation hardenable aluminum alloy

Compression testing of martensitic stainless steel with superimposed ultrasonic vibration - Michalski, Markus; Piott, Florian; Merklein, Marion (Procedia Engineering, 2017)
LFT Import::2019-07-29 (2233)
Keywords: Finite element method (FEM); high strength steel; metal forming; ultrasonic

Computer aided estimation of achievable accuracy for bending parts - Hagenah, Hinnerk; Backes, Frank (Sheet Metal 1998: Proceedings of the 6th International Conference on Sheet Metal, 1998)
LFT Import::2019-08-05 (1148)

Computer-Aided Generation of Bending Sequences for Die-Bending Machines - Hoffmann, Martin; Geißler, Uwe; Geiger, Manfred (Journal of Materials Processing Technology, Nr. 30, 1992)
The planning of bending sequences and the assigning of tools is a task that has to be done manually at the present time. As part of a computerized process-planning tool for sheet-metal parts, a bending-sequence generator has been developed. The bent part can be developed into the plane part automatically, technological data and know-how about the bending process and the press brake being included in this tool. The bending sequence generated by the computer can be simulated and altered ad libitum on a graphics screen. © 1992.
LFT Import::2019-08-05 (482)

Computer assisted design of actuators for high precision adjustment in micro technology - Hagenah, Hinnerk; Wurm, Thomas; Geiger, Manfred (Advances in Integrated Design and Manufacturing in Mechanical Engineering, 2005)
LFT Import::2019-08-05 (276)

Computer assisted design of actuator systems for laser micro adjustment - Plettke, Raoul; Hagenah, Hinnerk; Geiger, Manfred (Key Engineering Materials, 2007)
The adjustment of micro system components with laser forming using especially designed sheet metal actuator systems is a new and promising technology. However, due to the complexity of the design challenge and the contradicting targets that have to be considered computer assistance for the design of the actuator systems is needed. In order to build such a system several steps have to be taken. First, the actuators have to be modeled with all necessary data. Second, quality criteria have to be defined and fully automated assessment modules for every single objective have to be implemented. And third, an optimization system which utilizes the assessment modules must be developed to improve an initial design. This paper presents a solution for each of these steps. It closes with first results of a reduced version of the system as well as an outlook on the next development steps.
LFT Import::2019-07-11 (141)
Keywords: Actuator design; Evolutionary algorithm; Laser micro adjustment; Multi-criteria optimization

Computer assisted, knowledge based process design for sheet metal hydroforming using finite element simulation - Geiger, Manfred; Hagenah, Hinnerk; Kohlbauer, Rainer (Enterprises, production networks, 2004)
LFT Import::2019-08-05 (1034)

Concept for a closed loop control system for laser bending of extrusions - Menzel, Thomas; Geiger, Manfred; Brandt, Volker; Otto, Andreas (CIRP Journal of Manufacturing Systems, 2000)
LFT Import::2019-07-15 (789)

Concurrent Manufacturing of Parts and Tools for Sheet Metal Industry - Backes, Frank; Franke, Volker; Geiger, Manfred (The Second World Congress on Intelligent Manufacturing Processes & Systems IMP & S, Budapest, Ungarn, 10.06-13.06.1997, 1997)
LFT Import::2019-08-05 (691)

Connection strength of additive manufactured tool elements to the substrate - Junker, Daniel; Fedorov, Aleksandr; Hentschel, Oliver; Schmidt, Michael; Merklein, Marion (Trans Tech Publications Ltd, 2016)
In industry the increasing variety of products leads to shorter product life cycles. For parts made by forging processes this trend results in very high prizes, as the tool costs have to be assimilated with only few parts. To reduce the tool costs new, flexible processes have to be investigated and established in tool manufacturing. Laser based additive manufacturing is noted for its high flexibility and especially laser metal deposition (LMD) gets in the focus of the research as it allows adding material on free formed surfaces. Therefore it is already used for coating and repairing of forming tools. New investigations are made to qualify this process for the production of forging tools. The aim is to generate active elements onto a geometrical simple base unit. Within first investigations the manufacturing of high carbon hot work tool steel 1.2343 was analysed. The measured mechanical properties were similar to those of conventional manufactured material. The focus of this paper is the connection strength of the additively built structures to the substrate. Therefore cylindrical specimens for tensile tests are manufactured with the linkage zone in the parallel area, in which the highest tension will be achieved. To assess the strength of the connection a comparison with conventional manufactured steel will be made. Furthermore specimens produced with various settings will be tested to analyse the influence of the LMD process. Additionally post heat treated samples will be analysed to recognize the effect of the hardening on the strength of the specimens.
LFT Import::2019-08-05 (2264)
Keywords: Additive Manufacturing; Tool Manufacturing; Tool Steel Welding

Consideration of elastic tool deformation in numerical simulation of hydrofroming with granular material used as a medium - Grüner, Martin; Merklein, Marion (Key Engineering Materials, 2011)
LFT Import::2019-07-29 (1653)

Consideration of the manufacturing history of sheet metal components for the adaptation of a clinching process - Heyser, Per; Wiesenmayer, Sebastian; Frey, Philipp; Nehls, Thomas; Scharr, C; Flügge, Wilko; Merklein, Marion; Meschut, Gerson (Proceedings of the Institution of Mechanical Engineers Part L-Journal of Materials-Design and Applications, 2022)
The process chain for the manufacturing of sheet metal components in mass production includes various cutting and forming operations, which influence the resulting properties of the parts and therefore subsequent manufacturing steps, such as clamping and joining. It is shown that clamping of the components leads to superimposed residual stresses and geometry changes. Therefore, the part properties differ from the initial state of the semifinished products, which has to be considered in the design of clinched joints. This paper presents an approach for coupled determination of the properties of semifinished and finished parts during deep drawing and clamping as well as their effects on the joint quality during clinching. One method for the effective and efficient determination of the properties of semifinished products and components during production is using process data from the preceding manufacturing processes, which is concretely presented in this work. In addition to the interconnection of the entire production chain, it is necessary to define relevant process data for each individual manufacturing step and to correlate the data with the material properties reliably. Therefore, the cross-process interactions of different steps of the process chain for the manufacturing of sheet metal components and the effect of process variations on subsequent manufacturing steps are investigated. Consequently, the boundary conditions for a mechanical joining process based on data from preceding process steps can be predicted.<br
Keywords: Deep drawing; clamping; joining; process chain; manufacturing history

Constitutive Friction Law for the Description and Optimization of Tailored Surfaces - Henneberg, Johannes; Beyer, Florian; Löffler, Maria; Willner, Kai; Merklein, Marion (Sheet Bulk Metal Forming, 2021)

Contact Mask Technique for Laser Structuring of 3-D MID - Roth, Stephan; Dietel, C.; Eßer, Gerd; Geiger, Manfred (Proceedings of the IEMT Europe Symposium, Electronics Manufacturing and Development for Automotives, 1998)
Molded Interconnect Devices (MID) are promising polymer parts for many industrial applications to make possible complex functional components containing circuits, and to avoid costs in material and production. Already existing examples in the automotive field are a car dash board and a rear stop light. For suitable large scale production technologies for complex three-dimensional MID, development of new manufacturing processes is essential. Different technologies are used to generate circuit patterns on the substrate by photoimaging. The geometrical information can be transformed by using different mask technologies. Besides the common mask projection technique, a contact mask which contains the circuit geometry is also suitable. Therefore the circuits are generated in original scale by IR laser radiation on a polyvinyl chloride (PVC) sheet. The blackened polymer is non-transparent for UV radiation of common UV lamps and especially excimer lasers, used for imaging of photosensitive resists. For three-dimensional masks the sheet is formed by a deep drawing process.
LFT Import::2019-08-05 (1618)

Contact pressure-dependent friction characterization by using a single sheet metal compression test - Kraus, Martin; Lenzen, Matthias; Merklein, Marion (Wear, 2021)
Tribology has a major impact on process stability, product quality and tool life in metal forming processes. Today, the complex system of friction is simplified by the Coulomb friction coefficient or friction factor model for analytical and numerical process analysis. These friction values are determined in laboratory tests and assumed to be constant. Due to smoothing of the surface, displacement of lubricant from the active joint and locally different relative velocities, the friction state changes while forming. To achieve a high accuracy of finite element analysis, it is essential to consider these changing boundary conditions. Identifying strain-dependent friction coefficient or friction factor models by conventional characterization tests, such as the pin extrusion test or ring compression test, require a high number of experiments. Besides that, these tests are not suitable for low plastic strains due to their poor sensitivity. The sheet metal compression test, analyzed in this contribution, enables the description of the strain and contact pressure dependent progression of the friction values in one simple experimental setup. To determine the friction coefficients, the experimentally measured force-displacement curves will be assigned to friction coefficients in a numerically determined nomogram. The calibration of the nomogram is done analytically for the friction-free condition by using the flow curve determined in the uniaxial tensile test. The sheet metal compression test reacts sensitive to changes of the tribological system due to the high ratio of surface to specimen volume and the direct measuring of the press force as an evaluation quantity. The characterization of friction value progression is done for the materials DP600, DC06, Cu-OFE and CuZn30 with different tribological conditions. The results confirm that the friction values and thus the friction condition is changing during the forming process. Additionally, the validity limit of the friction coefficient model can be easily identified by analysing the friction coefficient progression.
CRIS-Team Scopus Importer:2021-03-05
Keywords: Contact mechanics; Contact pressure dependent friction model; Friction progression; Tribology; Tribophysics

Contact pressure-dependent friction compensation in upsetting tests with miniaturized specimens - Hetz, Peter; Rentz, Marcel; Merklein, Marion (Materials Research Proceedings, 2023)
Components produced by sheet metal forming can so far only be characterized locally to a limited extent using conventional tests, such as the tensile test or the hydraulic cupping test, due to the size of the specimen. A new approach based on miniaturized upsetting specimens taken from the sheet plane allows to determine the material properties of semi-finished products locally, for example in radii. However, in addition to this specific advantage, challenges such as friction between the specimen and the tool also appear with this testing method. For an accurate determination of the material parameters, it is therefore necessary to correct the test force by the friction coefficient. According to the state of the art, a variety of tests for friction coefficient characterization exist. By using a novel numerical method, friction coefficients for upsetting tests can be calculated contact pressure-dependent by means of an experimental single layer upsetting test. Therefore, in this paper, this method will be used for the first time to compensate the friction part in an upsetting test with miniaturized specimens as a function the contact pressure. This can improve the experimental mapping of the material behavior in the uniaxial compression stress state with increasing strain and hardening, since share of friction force increases with a higher deformation in the upsetting test. In contrast, a friction coefficient compensation based on an average value is provided in order to analyze, whether or in which case a contact pressure-dependent friction compensation is appropriate. In particular, for upsetting tests with miniaturized specimens, these results are relevant, since a major advantage of this test compared to conventional tests besides the local component characterization is the determination of material properties at high strains.
CRIS-Team Scopus Importer:2023-04-28
Keywords: Friction; Metal Forming; Upsetting Test

Controlled Rivet Deformation During Self-piercing Riveting Through a Tailored Strength Distribution Within the Rivet Material - Uhe, Benedikt; Kuball, Clara-Maria; Merklein, Marion; Meschut, Gerson (Proceedings of the 14th International Conference on the Technology of Plasticity - Current Trends in the Technology of Plasticity. ICTP 2023. Lecture Notes in Mechanical Engineering., 2023)

Controlled Section Bending by Using a Neural Network - Arnet, Horst; Geiger, Manfred (Proceedings of the 29th CIRP International Seminar on Manufacturing Systems, Osaka, Japan, 11.05.-13.05.1997, 1997)
LFT Import::2019-08-05 (685)

Controlled Stretchbending of Aluminium Extrusions - Sprenger, Axel (Sheet Metal 1998, 1998)
LFT Import::2019-08-05 (1622)

Control of a Hydroforming Press with Bayesian Networks - Deventer, R.; Niemann, H.; Celeghini, Martino (Proceedings of the ECAI 2004 16th Conference on Artificial Intelligence, 22.-27.08.2004, Valencia, Spain, 2004)
LFT Import::2019-08-07 (1083)

Control of the material flow in sheet-bulk metal forming using modifications of the tool surface - Löffler, Maria; Schulte, Robert Karl; Freiburg, D.; Biermann, Dirk; Stangier, D.; Tillmann, W.; Merklein, Marion (International Journal of Material Forming, 2019)
Sheet-bulk metal forming (SBMF) processes are characterized by a successive and/or simultaneous occurrence of different load conditions such as the stress and strain states. These conditions influence the material flow and often lead to a reduced geometrical accuracy of the produced components. To improve the product quality, a control of the material flow is required. One suitable approach, the local adaption of tribological conditions by means of surface modifications of tool or workpiece, so-called tailored surfaces. To control the material flow and thus to improve the component accuracy, methods to reduce and to increase friction are needed. The aim of this study is to determine requirements for necessary adaptions of the friction, the identification of tribological mechanisms for different types of tool-sided tailored surfaces as well as the verification of the effectiveness of these surface modifications to improve the results of a specific SBMF process. The numerical analysis of a combined deep drawing and upsetting process revealed that this process is characterized by two areas of varying tribological load conditions. Using a numerical analysis, the friction factor gradient between these two areas was identified as a main influencing factor on the material flow. Based on this finding, Chromium-based hard coatings for the reduction of the friction and high-feed milled surfaces for an increase of the friction were investigated regarding their frictional behaviour. The results of the ring-compression tests revealed that the carbon content and the post treatment of coated tool surfaces are relevant to reduce the friction. The increased profile depth of the milled surfaces was identified as the main influencing factor on the tribological behaviour of this kind of tailored surfaces. The effectiveness of both types of tailored surfaces was verified for the combined deep drawing and upsetting process.
CRIS-Team Scopus Importer:2019-05-28
Keywords: Coating; Milling; Sheet-Bulk Metal Forming; Surface Modification; Tribology

Correcting non circular dents by means of laser beam forming - Hutterer, Angelika; Hagenah, Hinnerk (Laser Assisted Net shape Engineering 4 - Proceedings of the LANE 2004, 2004)
LFT Import::2019-08-05 (1044)

Corrosion behaviour of self-piercing riveted joints with uncoated rivets in high nitrogen steel - Uhe, Benedikt; Kuball, Clara-Maria; Merklein, Marion; Meschut, Gerson (Production Engineering, 2024)

Cost estimation for large scale production of sheet metal parts using artificial neural networks - Geiger, Manfred; Knoblach, Jürgen; Backes, Frank (Production Engineering, 1998)
LFT Import::2019-07-16 (1150)

Coupling of analytical and numerical models for laser adjustment - Geiger, Manfred; Müller, Burkhard (Lasers in Engineering, 1998)
Miniaturisation in mass production requires more and more accuracy. Economic production of the demanded tolerances cannot be achieved with the available joining technology. The only possibility is laser beam adjustment of the already joined structural component. Modelling the behaviour of complex three-dimensional structures during laser adjustment becomes more and more necessary for building up a closed loop system which is designed to reach the accuracy of less than 0.1 μm. The model which is presented in this paper can be characterised by the fact that the plastic strain field after the laser irradiation is analytically calculated and included into a FEM program. The analytical solution includes the solution of the one-dimensional transient temperature field by pulsed irradiation assuming pulse durations in the range of nanoseconds. Based on this transient temperature field, a local maximum temperature is calculated. This non-time-dependent function is the basis of the calculation of the plastic deformation. Both elastic deformation and restraining is taken into account. The so-calculated plastic deformation is a residual stress source. For simple geometries like stripes, this plastic strain is used for calculating the bending angle by integrating over all three directions. On the other hand it is linearised and builds the input for the FE calculation. This method makes a fast calculation of the three-dimensional forming of complex geometries in short calculation times possible.
LFT Import::2019-07-16 (1592)
Keywords: Analytical model; Excimerlaser beam adjustment; FEM; Laser beam adjustment; Laser forming; Modelling

Coupling Respirometric HER and ORR Monitoring with Electrochemical Measurements - Strebl, Michael; Bruns, Mark; Virtanen, Sannakaisa (Electrochimica Acta, 2022)
An experimental setup for respirometric real-time monitoring of the kinetics of the H2 evolution reaction and the O2 reduction reaction coupled with electrochemical control is presented. Cathodic polarization of different metal electrodes was carried out to verify the accuracy, and sensitivity of this approach. It was found that the respirometric response was in excellent agreement with the applied electrical signal. Dissolution of H2 in the liquid phase can lead to a delayed detection of the evolved H2 in the gas phase. However, reducing the volume of electrolyte in the setup can diminish this lag in response time. The influence of H2 oxidation on reactive Pt and the generation of H2O2 on Au on the respirometric monitoring of cathodic reactions was investigated. Finally, the combined respirometric and electrochemical approach was applied to quantify dissolution of Al during cathodic polarization by relating the total cathodic charge with the electrical signal.
CRIS-Team Scopus Importer:2022-03-18
Keywords: Cathodic corrosion; Electrode kinetics; HER and ORR real-time monitoring; Respirometric Method

Crash behviour of various modern steels exposed to high deformation - Laumann, T.; Pfestorf, Markus; Beil, A.; Geiger, Manfred; Merklein, Marion (Key Engineering Materials, 2007)
LFT Import::2019-07-16 (1466)

Creation of the Data Base for the Process Design of the Three-Roll-Push Bending Process - Hagenah, Hinnerk; Vipavc, Daniel; Vatter, Peter; Cojutti, Massimo; Plettke, Raoul (7th CIRP Int. Conf. Intelligent Computation in Manufacturing Engineering, 2010)
LFT Import::2019-08-05 (136)

Cross-process chain influence of process variations in self-piercing riveting with regard to semi-finished product dimensions - Kuball, Clara-Maria; Uhe, Benedikt; Meschut, Gerson; Merklein, Marion (Journal of Advanced Joining Processes, 2024)

Cross-profile deep drawing of magnesium alloy AZ31 sheet metal for springback analysis under various temperatures - Suttner, Sebastian; Schmid, Harald; Merklein, Marion (18th International Conference on Sheet Metal, SHEMET 2019, 2019)
LFT Import::2019-08-05 (2363)

Cross Transport in a Multi-Station Former for Microparts - Geiger, Manfred; Egerer, Emil; Engel, Ulf (Production Engineering, 2002)
LFT Import::2019-07-16 (1664)

Customized Exposure Strategies for Manufacturing Hybrid Parts by Combining Laser Beam Melting and Sheet Metal Forming - Huber, Florian; Papke, Thomas; Kerkien, Melanie; Tost, Florian; Geyer, Georg; Merklein, Marion; Schmidt, Michael (2018)

Customized exposure strategies for manufacturing hybrid parts by combining laser beam melting and sheet metal forming - Huber, Florian; Papke, Thomas; Kerkien, Melanie; Tost, Florian; Geyer, Georg; Merklein, Marion; Schmidt, Michael (Journal of Laser Applications, 2019)

Cutting of sandwich aluminium structures by laser beam and abrasive waterjet cutting - Maros, Z.; Polak, H.; Kach, Andreas (Gépgyártás, 2001)
LFT Import::2019-07-15 (911)

Cyber-Physical Systems in the Context of Industry 4.0: A Review, Categorization and Outlook - Oks, Sascha Julian; Jalowski, Max; Lechner, Michael; Mirschberger, Stefan; Merklein, Marion; Vogel-Heuser, Birgit; Möslein, Kathrin (Information Systems Frontiers, 2022)
Cyber-physical systems (CPS) offer great potential for the digital transformation of industrial value creation in the context of Industry 4.0. They unify and integrate several technological approaches, including big data analysis and artificial intelligence, enhancing real-time monitoring and control of manufacturing processes. An extensive knowledge base formed by various disciplines, including information systems, engineering, and computer science, already exists for CPS. However, this knowledge has not been holistically captured and structured to date. To address this research gap, this study conducts a large-scale literature review of 2365 papers representing the current state of the research and then develops a novel categorization on industrial CPS with 10 sections, 32 areas, and 246 fields. The categorization is presented in hierarchical graphical form and can also be utilized as a web tool. To conclude, a perspective on future research needs and potentials to enhance Industry 4.0 in both research and practice are offere
Keywords: Cyber-physical systems; Industry 4.0; State of research; Categorization

Cyclic tension test of AZ31 magnesium alloy at elevated temperature realized in a miniaturized uniaxial tensile test setup - Suttner, Sebastian; Merklein, Marion (Materials Science Forum, 2016)
The use of new materials, e.g. aluminum and magnesium alloys, in the automotive and aviation sector is becoming increasingly important to reach the global aim of reduced emissions. Especially magnesium alloys with their low density offer great potential for lightweight design. However, magnesium alloys are almost exclusively formable at elevated temperatures. Therefore, material characterization methods need to be developed for determining the mechanical properties at elevated temperatures. In particular, cyclic tests at elevated temperatures are required to identify the isotropic-kinematic hardening behavior, which is important for numerically modeling the springback behavior. In this contribution, a characterization method for determining the cyclic behavior of the magnesium alloy AZ31B at an elevated temperature of 200 °C is presented. The setup consists of a miniaturized tensile specimen and stabilization plates to prevent buckling under compressive load. The temperature in the relevant area is introduced with the help of conductive heating. Moreover, the complex kinematic model according to Chaboche and Rousselier is identified, to map the transient hardening behavior of AZ31B after load reversal, which cannot be modeled with a single Bauschinger coefficient.
LFT Import::2019-07-29 (2186)
Keywords: Bauschinger effect; Characterization; Cyclic testing; Magnesium alloy

Das Verbundprojekt -3D-Bearbeiten mit CO2-Hochleistungslasern- im Überblick - Geiger, Manfred; Hoffmann, Peter (3D-Bearbeiten mit CO2-Hochleistungslasern, 1992)
LFT Import::2019-07-15 (472)

Data acquisition and control at the edge: a hardware/software-reconfigurable approach - Streit, Franz-Josef; Wituschek, Simon; Pschyklenk, Michael; Becher, Andreas; Lechner, Michael; Wildermann, Stefan; Pitz, Indra; Merklein, Marion; Teich, Jürgen (Production Engineering, 2020)
Today’s manufacturing facilities and processes offer the potential to collect data on an unprecedented scale. However, conventional Programmable Logic Controllers are often proprietary systems with closed-source hardware and software and not designed to also take over the seamless acquisition and processing of enormous amounts of data. Furthermore, their major focus on simple control tasks and a rigid number of static built-in I/O connectors make them not well suited for the big data challenge and an industrial environment that is changing at a high pace. This paper, advocates emerging hardware- and I/O reconfigurable Programmable System-on-Chip (PSoC) solutions based on Field-Programmable Gate Arrays to provide flexible and adaptable capabilities for both data acquisition and control right at the edge. Still, the design and implementation of applications on such heterogeneous PSoC platforms demands a comprehensive expertise in hardware/software co-design. To bridge this gap, a model-based design automation approach is presented to generate automatically optimized HW/SW configurations for a given PSoC. As a case study, a metal forming process is considered and the design automation of an industrial closed-loop control algorithm with the design objectives performance and resource costs is investigated to show the benefits of the approac
Keywords: FPGA; PSoC; Hardware/software co-design; Model-based engineering; Industrial automation; Manufacturing technology; Forming process; Motor control

Data-Based Control of A Multi-Step Forming Process - Schulte, Robert Karl; Frey, Philipp; Hildenbrand, Philipp; Vogel, Manfred; Betz, C.; Lechner, Michael; Merklein, Marion (Proc. International Deep Drawing Research Group Conf. IDDRG 2017, 2017)
LFT Import::2019-08-05 (2253)

Data-driven analysis of cold-formed pin structure characteristics in the context of versatile joining processes - Römisch, David; Zirngibl, Christoph; Schleich, Benjamin; Wartzack, Sandro; Merklein, Marion (IOP Conference Series, 2021)
Due to increasingly strict emission targets and regulatory requirements, especially for companies in the transport industry, the demand for multi-material-systems is continuously rising in order to lower energy consumption. In this context, mechanical joining processes offer an environmentally friendly and flexible alternative to established joining methods, especially in the field of lightweight design. For example, cold-formed cylindrical pin structures show high potentials in joining multi-material-systems without auxiliary elements. The pin structures are joined either by pressing them directly into the joining partner or by caulking with a pre-punched part. However, to evaluate the strength of the joint and to ensure the joining reliability for versatile processes, such as changing joining partners or batch variations, engineering designers currently have only limited design principles available compared to thermal joining processes. Consequently, the design of an optimal pin joint requires cost- and time-intensive experimental investigations and adjustments to design or process parameters. As a solution, data-driven methods offer procedures for structuring data and identifying dependencies between varying process parameters and resulting pin structure characteristics. Motivated by this, the paper presents an approach for the data-driven analysis of cold-formed pin structures and offers a deeper understanding of how versatile processes affect the pin characteristics. Therefore, the application of an intelligent design of experiment in combination with several machine learning methods enable the setup of a best-fitting meta-model. Resulting, the determination of a mathematical model provides the opportunity to accurately estimate the pin height considering only relevant geometrical and process parameters with a prediction quality of 95

Data-driven inline optimization of the manufacturing process of car body parts - Purr, S.; Wendt, A.; Meinhardt, J.; Moelzl, K.; Werner, A.; Hagenah, Hinnerk; Merklein, Marion (IOP Conference Series: Materials Science and Engineering, 2016)
LFT Import::2019-07-29 (2213)

Data-driven Model Development for Quality Prediction in Forming Technology - Kirchen, Iris; Vogel-Heuser, Birgit; Hildenbrand, Philipp; Schulte, Robert Karl; Vogel, Manfred; Lechner, Michael; Merklein, Marion (15th IEEE International Conference on Industrial Informatics (INDIN), 2017)
this investigation data recorded from a flexible rolling process is processed by data driven methods to develop a quality prediction model for manufactured blanks. A concept for an incremental prediction method is proposed, which takes into account the specific character of the discrete manufacturing process. The method is evaluated based on a data set of process and quality data provided by a test rig. By the example of a specific quality parameter the effectiveness of the proposed method is confirmed. A precise quality prediction model is developed, which predicts the quality value with a high accuracy.
LFT Import::2019-08-05 (2252)
Keywords: automated Production Systems; data analytics; quality prediction

Data driven prognosis of clinch joints in multi-material design - Ludwig, Jean-Patrick; Lontsi, Seraphin Tsi-Nda; Neumann, Jonas; Kappis, Lukas; Scharr, Christian; Flügge, Wilko; Merklein, Marion; Meschut, Gerson (ESAFORM2025, 2025)
Clinching is a conventional mechanical joining process used in Multi-Material Design in the automotive sector. To receive the desired geometrical characteristics in clinch joints, correct process design is required. To reduce the cost of finding fitting process parameters, numerical simulation of the joining process can be used to predict the geometrical characteristics, such as interlock, instead of an experimental approach. These numerical simulation models consume computational resources and time. In this paper machine learning is used to find correlations between features of the joining process and geometrical characteristics in the joint. This serves the purpose of predicting the joint’s target values more resource-efficiently. Modelling with machine learning requires a structured dataset with sufficient parameter variation. To create this data base the following procedure was used. For joining partners, a HC340LA steel alloy with 2 mm material thickness was used punch-sided and an EN AW 5182 aluminum alloy with 1.5 mm thickness was used die-sided. For this combination a suitable tool combination and punch distance was experimentally identified. A finite element model was created to reproduce the joining process. For the modelling of the material of both joining partners flow curves determined by Vallaster et al. were used [1]. The punch and die were recreated digitally by opto-electronic measurements and transformed into a mesh suitable for numerical simulation. The model was validated by comparing process values like the maximum force applied by the punch and geometrical values in the joints cross section. Additionally, a process window for suitable punch distances was experimentally determined. Afterwards a variation of 70 different process designs was conducted with variants inside and outside the process window. The results were used for training, testing and validating various machine learning models. All models competed against each other to find the must suited model to predict every geometric value. To ensure good model performances and prevent the model from overfitting, a tenfold cross validation was used for validating the models. Analysis of the results gives the following key findings: i) Good predictability is reached for the interlock and sheet thickness of the joint. ii) Prediction neck thickness showed low error values, but also low correlation. iii)The prediction of those key values for evaluating clinch joint characteristics by machine learning models positively impacts needed resources in comparison to numerical model

Data Flow for the Development of Laser Manufactured Products - Geiger, Manfred; Kach, Andreas (35th CIRP-International Seminar on Manufacturing Systems ISMS, 2002)
LFT Import::2019-08-05 (1675)

Datenerfassung für die Anwendung lernender Algorithmen bei der Herstellung von Blechformteilen - Purr, Stephan (Friedrich-Alexander-Universität Erlangen-Nürnberg, 2020)
The process of industrially producing shaped sheet metal parts is influenced by a large number of fluctuating factors. Therefore, quality problems appear to occur randomly and cause defective parts and a loss of productivity. A suitable way to improve these processes is the application of data analysis and statistical methods like machine learning, which require a large amount of data. So far, the data base and suitable methods for data acquisition are lacking for the use of these methods. Therefore, in this work, a generally valid and transferable method for recording and saving relevant influencing and resultant variables during the series production of sheet metal parts has been developed. This method and the resulting data are the basis for the analysis of correlations in the process, the prediction of quality by learning algorithms and the calculation of suitable press settings. These use cases were tested in the work and the results were evaluated. Thus, the functionality of the data acquisition and the expected potentials could be confirme

Datenorganisation in einem wissenbasierten System zur Biegestadienplanung - Geiger, Manfred; Hoffmann, Martin (CIM-Management, 1990)
LFT Import::2019-07-15 (729)

Deep Drawing of Friction Stir Welded Aluminium Tailored Blanks - Geiger, Manfred; Merklein, Marion; Giera, Artur (Proceedings of IDDRG, 24.-26.05., 2001)
LFT Import::2019-08-05 (1064)

Deep drawing of friction stir welded thin sheet aluminium-steel tailored hybrids - Merklein, Marion; Giera, Artur; Geiger, Manfred (Steel Research International, 2005)
LFT Import::2019-07-16 (1223)
Keywords: Aluminium steel tailored hybrids; Deep drawing; Forming behaviour; Friction stir welding

Definition and validation of a customized classification system for sheet metal bending parts - Schmid, Daniel; Merklein, Marion (Materials Research Proceedings, 2023)
The industry demands an increasing individualization, which leads to a rising variety of sheet metal parts. The consequence for sheet metal manufacturers are larger amounts of product data, smaller batch sizes and a larger quantity of different parts per year. The challenge for an efficient company is the availability and use of the corporate product data. Classification is a suitable tool for organizing corporate product data sets. In order to better reflect the individualization of customer demands and the resulting flexible manufacturing processes in a classification system, a method is needed to adapt the classification system based on the frequently used feature list. In the context of this paper, features are defined and parts are classified that are manufactured with the technology of air bending. It is a contribution to the creation of more precise approaches to the sheet metal part classification with simultaneous validation by a measurable characteristic. Focus is placed on the validation of the system with empirical measurement data. This allows every company to optimize and validate their own classification system.
CRIS-Team Scopus Importer:2023-04-28
Keywords: Bending; Optimization; Sheet Metal

Der Einsatz des Festkörperlasers zum Laserstrahl-Mikroschweißen in der Elektronikfertigung - Geiger, Manfred; Glasmacher, Matthias; Pucher, Hans-Jörg; Hutfless, Joachim (Laser, 1994)
LFT Import::2019-07-15 (589)

Der SFB 396 im Überblick- Beiträge zum Berichts- und Industriekolloquium - Geiger, Manfred; Hagenah, Hinnerk (Robuste, verkürzte Prozessketten für flächige Leichtbauteile: Tagungsband zum Industriekolloquium, 2006)
LFT Import::2019-08-05 (264)

Design and Implementation of an Additively Manufactured Reactor Concept for the Catalytic Methanation - Hauser, Alexander; Neubert, Michael; Feldner, Alexander; Horn, Alexander; Grimm, Fabian; Karl, Jürgen (Applied Sciences, 2022)
The methanation process is discussed as one way to chemically store renewable energy in a future energy system. An important criterion for its application is the availability of compact, low-cost reactor concepts with high conversion rates for decentralized use where the renewable energy is produced. Current research focuses on the maximization of the methane yield through improved temperature control of the exothermic reaction, which attempts to avoid both kinetic and thermodynamic limitations. In this context, traditional manufacturing methods limit the design options of the reactor and thus the temperature control possibilities. The use of additive manufacturing methods removes this restriction and creates new freedom in the design process. This paper formulates the requirements for a novel methanation reactor and presents their implementation to a highly innovative reactor concept called ‘ADDmeth’. By using a conical reaction channel expanding from Ø 8 to 32 mm, three twisted, expanding heat pipes (Ø 8 mm in evaporation zone, Ø 12 mm in condenser zone) and a lattice structure for feed gas preheating and mechanical stabilization of the reactor, the design explicitly exploits the advantages of additive manufacturing. The reactor is very compact with a specific mass of 0.36 kg/kW and has a high share of functional volume of 52%. The reactor development was accompanied by tensile tests of additively manufactured samples with the used material 1.4404 (316 L), strength calculations for stability verification and feasibility studies on the printability of fine structures. Ultimate tensile strengths of up to 750 N/mm2 (at room temperature) and sufficiently high safety factors of the pressure-loaded structures against yielding were determined. Finally, the paper presents the manufactured bench-scale reactor ADDmeth1 and its implementation.
CRIS-Team Scopus Importer:2022-10-07
Keywords: additive manufacturing; catalytic methanation; conic reaction channel; heat pipes; reactor design

Design and Implementation of Neural Networks for Matching Contours in CAD Models - Wilke, Peter; Geiger, H; Greska, Wolfgang; Behrendtz, Jürgen (Proceedings of the International Conference on Artificial Neural Networks (ICANN 94), 1994)

Design and Realization for a Micro Optical Rotary Joint - Stark, Markus; Eßer, Gerd; Lamott, A.; Poisel, H. (Proceedings O.M.P. OPTO-Conference, 2004)
LFT Import::2019-08-05 (1116)

Designing, manufacturing and processing of Tailored Blanks in a sheet-bulk metal forming process - Schulte, Robert Karl; Hildenbrand, Philipp; Lechner, Michael; Merklein, Marion (45th SME North American Manufacturing Research Conference, NAMRC 45, LA, USA, 2017)
Sheet-bulk metal forming is an innovative method for the manufacturing of functional components by applying bulk metal forming processes or combined sheet and bulk metal forming processes to sheet metal. The investigated process combines deep drawing and upsetting. Occurring 2D and 3D stress and strain states lead to challenges regarding the material flow control during the forming process to ensure a high die filling and accurate part geometry. Regarding these challenges, the application of conventional semi-finished products is not expedient wherefore Tailored Blanks with a process adapted sheet thickness distribution are applied to the forming process. The Tailored Blank geometry is designed by a numerical analysis and manufactured by an orbital forming process considering the resulting geometric part properties during deep drawing and upsetting. Therefore, the whole process chain from the conventional circular blank to the finished functional component is linked and modelled. This enables a realistic description of the part properties as the effective plastic strain caused in the manufacturing of semi-finished products is taken into account in the processing of the material. Subsequently the results are verified by experimental tests.
LFT Import::2019-08-05 (2231)
Keywords: Deep drawing; Finite element method (FEM); Forming; Sheet metal

Design, Manufacturing and Tribological Performance of Microtextured Bucket Tappets for Friction Reduction in the Valve Train - Marian, Max; Zahner, Michael; Tremmel, Stephan; Andreas, Kolja; Merklein, Marion; Wartzack, Sandro (6th World Tribology Congress, 2017)
In order to improve lubricating conditions as well as friction and wear behavior, the surfaces of contacting bodies in lubricated tribological contacts can be microtextured. While this approach has already reached industrial application for lower loaded contacts, the effects for higher loaded contacts, where elastic deformation plays a significant role, are still topic of basic research. For this reason, microtextures are adapted to the conditions of the tribological system of the bucket tappet/camshaft contact in the valve train as a demonstrator and major contributor to combustion engine losses. The tribological performance of various microtexture geometries and arrangements is analyzed on a one bucket tappet/one cam test-rig using series production valve train parts. A resistive measurement system is first applied to the highly dynamic tappet/camshaft contact and allows the investigation of the correlation between lubricating conditions and friction force. In the tests, a significant friction force reduction using microtextured surfaces compared to polished surfaces is achieved. Additionally, quantitative ex-situ wear characterization is carried out for long-run test cycles, using Laser Scanning Microscopy. Thus, wear mechanisms and rates are compared with the measurements of lubricating conditions and friction force. Besides the identification of advantageous microtexture geometries and arrangements regarding the tribological performance, possibilities and limitations of the manufacturing technology are examined. In order to realize high-volume production, a micro coining process was studied. In this regard the manufacturing of the coining punch using µEDM and the coining process itself were analyzed with respect to accuracy and reproducibility. Additionally, the durability of the pins was investigated for the micro coining process. The limitations of the manufacturing process and of the micro coining process are summarized in a process windo
Keywords: Microtextures; Micro Coining; EHL Contact

Design of Manufacturing Processes for the Cold Bulk Forming of Small Metal Components from Metal Strip - Stellin, Tommaso (Friedrich-Alexander-Universität Erlangen-Nürnberg, 2017)
The major objective of the work is to generate a basic understanding of manufacturing small metal component from metal strip, in order to reduce the handling limits in multi-stage microforming processes. The design supported by FE-modelling allows a simultaneous analysis of microforming process and strip deformation, in order to ensure a precise handling system. The selection of appropriate process parameters, together with the adoption of harder and thinner raw material, improves the material flow-control and an increase of the microscopic workpiece volume with a simultaneous achievement of a stable process conforming to mass-productio

Design of Micro Forming Proces¬ses Fundamentals, Mate¬rial Data and Friction Behaviour. - Geiger, Manfred; Meßner, Arthur; Engel, Ulf; Kals, Roland; Vollertsen, Frank (Chipless 2000 Advancing Chipless Component Manufacture, Proceedings of the 9th International Cold Forging Congress, 1995)
None
LFT Import::2019-08-05 (1971)

Design of Micro-Forming Processes - Fundamentals, Material Data and Friction Behaviour - Geiger, Manfred; Meßner, Arthur; Engel, Ulf; Kals, Roland; Vollertsen, Frank (Proceedings of the 9th International Cold Forging Congress, 1995)
LFT Import::2019-08-05 (550)

Design Principles of Tailored Heat Treated Blanks for the manufacturing of complex car body parts - Merklein, Marion; Vogt, Uwe (Proceedings of the IDDRG 2008, 2008)
LFT Import::2019-08-05 (1528)

Detection and Prevention of Hot Cracks during Laser Welding of Aluminium Alloys Using Advanced Simulation Methods - Komlodi, Attila (Friedrich-Alexander-Universität Erlangen-Nürnberg, 2006)
Hot cracking, especially in alloys with increased hot crack susceptibility, is quite difficult to prevent, since there existed so far no adequate method to detect satisfactory welding parameters. Within this thesis a method, based on FE- simulations, is introduced, which can help the technologist to identify welding parameters advantageous to prevent hot cracking. Thus, with the help of this method time and costs can be saved during the technology desig

Detection of the real plastification in a biaxial tension test - Hußnätter, Wolfgang (Key Engineering Materials, 2007)
The dimensioning of tools and components in fields of metal forming is more and more based on process modeling and numerical simulation and therefore the material data are of main importance. Since the mechanical behavior of components in sheet metal forming processes highly differs according to real, i.e. biaxial stress condition because of anisotropic effects, the knowledge of material properties based on experimental investigations by biaxial loading is essential. Therefore, a novel experimental setup for the determination of yield loci has been developed at the Chair of Manufacturing Technology (LFT) in Erlangen. In this paper this setup is introduced. In comparison to existing setups me design of kinematics of the LFT-setup is sniplified and therefore the controllability of loading and measuring devices is enhanced. On the one hand the strains are directly measured by an optical measurement system, but on the other hand the regarding yield stresses cannot experimentally be determined, they have to be calculated from the quotient of force and the representative cross-sectional area of the specimen. Thus, a very detailed determination of both forces and cross section of the sheet is necessary. Since the specimens are not actively loaded, the reaction forces in rolling direction (RD) and transverse direction (TO) have to be calculated from the measured contact forces between tool and sheet to achieve the first component for the quotient. Using the results of the thinning analysis of the sheets it can be noticed, that the area of plastification is not constant for increasing forming. Therefore, the calculation of the yield stress must contain a variable formulation for the cross-sectional area.
LFT Import::2019-07-16 (1384)
Keywords: Hardening; Material characterization; Sheet metal forming; Yielding

Determination of contact stresses in the boundary area considering elastomere-pad bending as example - Geiger, Manfred; Merklein, Marion; Trägler, Horst; Nock, Marco (Production Engineering - Annals of the WGP, 2005)
LFT Import::2019-08-05 (1218)

Determination of Data for the Hot Stamping Process - Geiger, Manfred; Merklein, Marion; Hoff, Cornelia (Production Engineering. Annals of the German Academic Society for Production Engineering, 2006)
LFT Import::2019-08-05 (1344)

Determination of Forming Limit Curves - Strain Path and Failure Analysis - Kohl, Doris; Merklein, Marion (Key Engineering Materials, 2022)
With the goal to define a cost-effective and efficient process to identify adequate materials for sheet metal forming processes, it is crucial to evaluate the formability of materials. Forming limit curves (FLC) are used to analyze the forming and failure limits of sheet metals and dependence of the major (ε1) and minor strain (ε 2) from the uniaxial stress-strain area through the plane-strain point to the biaxial strain area. According to ISO 12004-2, the FLC is performed by Nakajima or Marciniak tests. Due to the experimental setup and the preconditions, pre-stretching occurs in the specimens and bending and friction effect are the result. The determination of the onset of necking (FLC) results mathematically from a “best-fit inverse parabola” on section lines. In addition, the failure point, i.e. the maximum strain value one frame before failure, is also analyzed. In contrast, tensile, notched tensile and hydraulic bulge tests, which are known in the literature as basic tests for the determination of the FLC, exhibit a linear strain path evaluation. These tests are used in this investigation as an alternative for the determination of the FLC. The behavior of the various strain paths of Nakajima and the alternative methods are examined for necking and cracking. Furthermore, the fracture surfaces are investigated by confocal laser scanning microscopy to identify influences of the different FLC methods on the fracture mechanics. FLCs were conducted with the Nakajima and the alternative FLC characterization method for a ductile steel (DX54D). To ensure transferability, the tensile tests are also performed with a high-strength steel (DP800). The FLC of the ductile steel, generated through the alternative method, exhibits a similar shape to the Nakajima generated FLC with the advantage of a constant strain rate leading to linear strain paths and a lower number of tests. The same results are achieved for the uniaxial strain tests with DP800.<br

Determination of forming limit diagrams? a new analysis method for characterization of materials' formability - Geiger, Manfred; Merklein, Marion (CIRP Annals - Manufacturing Technology, 2003)
LFT Import::2019-07-16 (1007)

Determination of forming limit diagrams at elevated temperatures for failure prediction within hot stamping of quenchenable ultra high strength steels - Lechler, Jürgen; Merklein, Marion (Tagungsband International Conference on Plasticity, 2008)
LFT Import::2019-08-05 (1552)

Determination of Forming Limits in Sheet Metal Forming Using Deep Learning - Jaremenko, Christian; Ravikumar, Nishant; Affronti, Emanuela; Merklein, Marion; Maier, Andreas (Materials, 2019)
The forming limit curve (FLC) is used to model the onset of sheet metal instability during forming processes e.g., in the area of finite element analysis, and is usually determined by evaluation of strain distributions, derived with optical measurement systems during Nakajima tests. Current methods comprise of the standardized DIN EN ISO 12004-2 or time-dependent approaches that heuristically limit the evaluation area to a fraction of the available information and show weaknesses in the context of brittle materials without a pronounced necking phase. To address these limitations, supervised and unsupervised pattern recognition methods were introduced recently. However, these approaches are still dependent on prior knowledge, time, and localization information. This study overcomes these limitations by adopting a Siamese convolutional neural network (CNN), as a feature extractor. Suitable features are automatically learned using the extreme cases of the homogeneous and inhomogeneous forming phase in a supervised setup. Using robust Student's t mixture models, the learned features are clustered into three distributions in an unsupervised manner that cover the complete forming process. Due to the location and time independency of the method, the knowledge learned from formed specimen up until fracture can be transferred on to other forming processes that were prematurely stopped and assessed using metallographic examinations, enabling probabilistic cluster membership assignments for each frame of the forming sequence. The generalization of the method to unseen materials is evaluated in multiple experiments, and additionally tested on an aluminum alloy AA5182, which is characterized by Portevin-LE Chatlier effects.
CRIS-Team WoS Importer:2019-05-07

Determination of frictional and thermal characteristics for hot stamping with respect to a numerical process design - Stöhr, Thomas; Merklein, Marion; Lechler, Jürgen (Proceedings 1st International Conference Hot Sheet Metal Forming of High-Performance Steel - CHS2, 2008)
LFT Import::2019-08-05 (213)

Determination of Friction Coefficients for the FE Analysis of Sheet Forming of Tailored Welded Blanks - Tolazzi, Massimo; Merklein, Marion (Sheet Metal 2005, Proceedings of the 11th International Conference on Sheet Metal; Advanced Materials Research, 2005)
The finite element analysis of sheet forming processes needs precise and reproducible data of the tribological conditions, which influence the material flow during the process. In this work the friction coefficient and its dependency on the hardness and surface topography of the blank are investigated. The selected materials are four steels with different surface qualities and coatings, FeP04, ZStE340, DP450 and TRIP800, which are joined by laser welding. Moreover, each material both with and without weld seam, was tested at three different values of normal contact pressure in a strip drawing test. The topography of both the base material and the weld line was obtained by measuring the surface roughness and implementing the data in a surface analysis software. Micro-hardness profiles along the tailored welded blanks were also determined. The strip drawing test was used to measure the friction coefficient between sheet metal and tool both in the case of tailored welded blanks and base material. The comparison between the results obtained for base materials and tailored welded blanks shows that the presence of the weld seam causes a clear increase of the friction between blank and tool.
LFT Import::2019-08-05 (1128)
Keywords: Sheet metal; Tailored blank; Tribology

Determination of friction coefficients for the finite element analysis of double sheet hydroforming with a modified dup test - Tolazzi, Massimo; Vahl, Meik; Geiger, Manfred (ESAFORM, 2003)
LFT Import::2019-07-15 (950)

Determination of friction coefficients in deep drawing by modification of Siebel's formula for calculation of ideal drawing force - Grüner, Martin; Merklein, Marion (Production Engineering, 2014)
LFT Import::2019-07-29 (2031)

Determination of Influencing Parameters of the Hot Stamping Process - Merklein, Marion; Lechler, Jürgen (Tagungsband AsiaSteel 06 conference, Fukuoba, Japan, 2006)
LFT Import::2019-08-05 (1267)

Determination of Material and Process Characteristics for Hot Stamping Processes of Quenchenable Ultra High Strength Steels with Respect of a Numerical Process Design - Merklein, Marion; Lechler, Jürgen (Sae World Congress 2008, 2008)
LFT Import::2019-08-05 (1554)

Determination of material intrinsic length and strain gradient hardening in microbending process - Li Hezong,; Dong Xianghuai,; Wang Qian,; Shen Yu,; Diehl, Alexander; Hagenah, Hinnerk; Engel, Ulf; Merklein, Marion (International Journal of Solids and Structures, 2011)
Microbending experiments of pure aluminum show that the springback angles increase with the decrease of foil thickness, which indicates obvious size effects and attributes to plastic strain gradient hardening. Then a constitutive model, taking into accounts both plastic strain and plastic strain gradient hardening, is proposed to analyze the microbending process of thin foil. The model is based on the relationship between shear yield stress and dislocation density, in which the material intrinsic length is related to material properties and average grain numbers along the characteristic scale direction of part. It is adopted in analytical model to calculate the non-dimensional bending moment and predict the springback angle after microbending. It is confirmed that the predictions by the proposed hardening model agree well with the experimental data, while those predicted by the classical plasticity model cannot capture such size effects. The contribution of plastic strain gradient increases with the decrease of foil thickness and is independent on the bending angle. © 2010 Elsevier Ltd. All rights reserved.
LFT Import::2019-07-29 (720)
Keywords: Gradient of effective plastic strain; Material intrinsic length; Microbending; Springback

Determination of Mechanical Properties for the Hydroforming of Magnesium Sheets at Elevated Temperature - Hecht, Joachim; Pinto, S.; Geiger, Manfred (Sheet Metal 2005, Proceedings of the 11th International Conference on Sheet Metal, 2005)
LFT Import::2019-08-05 (1143)
Keywords: Hydroforming; Magnesium; Sheet metal