Wear in wind turbine pitch bearings—A comparative design study - Schwack, Fabian; Halmos, Fabian; Stammler, Matthias; Poll, Gerhard; Glavatskih, Sergei (Wind Energy, 2021)
We tested two types of ball bearings with an outer diameter of 750 mm to learn more about the challenges of oscillating motions for pitch bearings. The experimental conditions are derived from aero-elastic simulations, long-term wind speed measurements and a scaling method that considers loads and pitch angles. As a result, the parameters relevant for pitch bearings are represented appropriately, and the findings are transferable to other bearing sizes. For the tested parameter sets, severe wear occurred for over 90% of the exposed contact areas after 12 500 oscillating cycles. Decreasing the number of cycles to 1250 leads to a mix of exposed areas with 13% severe wear, 32% mild wear and 55% no wear, with no apparent pattern. The results demonstrate that a comparatively small amount of consecutive cycles can lead to severe wear. A new type of bearing tested showed less wear for the selected operating conditions.
CRIS-Team Scopus Importer:2021-11-19
Keywords: bearing design; blade bearing; downscaled experiments; individual pitch control

Wear Mechanism of Superhard Tetrahedral Amorphous Carbon (ta-C) Coatings for Biomedical Applications - Rothammer, Benedict; Schwendner, Michael; Bartz, Marcel; Wartzack, Sandro; Böhm, Thomas; Krauß, Sebastian; Merle, Benoit; Schroeder, Stefan; Uhler, Maximilian; Kretzer, J. P.; Weihnacht, Volker; Marian, Max (Advanced Materials Interfaces, 2023)
Tetrahedral amorphous carbon (ta-C) coatings have the potential to protect biomedical implants from wear and increase their service life. This study elucidates the biocompatibility, mechanical properties, adhesion, and wear resistance of ta-C coatings fabricated by physical vapor deposition on cobalt-chromium-molybdenum (CoCr) and titanium (Ti64) alloys as well as ultrahigh molecular weight polyethylene (UHMWPE). Satisfactory cytocompatibility is verified using contact angle and surface tension measurements as well as indirect and direct cell testing. Scratch testing demonstrates excellent adhesion to the substrates and as confirmed by nanoindentation, the coatings represent an up to 13-fold and 182-fold increase in hardness on the hard and soft materials. In metal pin-on-UHMWPE disk sliding experiments under simulated body fluid lubrication, the wear rates of the disk are reduced by 48% (against CoCr) and 73% (against Ti64) while the pin wear rates are reduced by factors of 20 (CoCr) and 116 (Ti64) compared to uncoated pairings. From optical and laser scanning microscopy, Raman measurements, and particle analyses, it is shown that the underlying substrates remain well protected. Nonetheless, focused ion beam scanning electron microscopy revealed coating process-related and thermally driven subductions as well as tribologically induced near-surface fatigue, which can potentially constitute critical wear mechanism
Keywords: biotribology; diamond-like carbon; physical vapor deposition coatings; synovial joint; total knee replacements; wear-resistance

Wear Modeling of non-conformal Rolling Contacts subjected to Boundary and Mixed Lubrication - Winkler, Andreas; Bartz, Marcel; Wartzack, Sandro (23rd International Colloquium Tribology 2022, 2022)
Keywords: Verschleißsimulation; Mischreibung; Grenzreibung; Wälzlager

Web-Based Assessment of CAD Data in Undergraduate Design Education - Krüger, Daniel; Wartzack, Sandro (ASME 2014 12th Biennial Conference on Engineering Systems Design and Analysis Volume 1: Applied Mechanics; Automotive Systems; Biomedical Biotechnology Engineering; Computational Mechanics; Design; Digital Manufacturing; Education; Marine and Aerospace Applications, 2014)
In this contribution a web-based assessment framework for CAD data is proposed which has been developed based on the experience the authors made giving undergraduate courses at a German university. The framework is the backbone of a hybrid teaching concept combining conventional classroom lessons with e-learning elements. In-between the classroom lessons the students receive instructions on a particular modeling task via a web-interface. The same interface is used to hand in solutions in form of CAD files. Teachers who need to assess these solutions are supported by a semi-automated analysis of the CAD geometry. An algorithm compares each solution with a reference solution in order to reveal typical modeling mistakes. After the assessment is completed the students receive a feedback on their work. A case study on the application of the teaching concept in a course with 691 participants held during summer term 2013 reveals the positive experience the authors made using the system and points to some issues that need to be improved in the future.
UnivIS-Import:2015-04-16:Pub.2014.tech.FT.FT-KLMEFK.webbas
Keywords: Computer-aided design; Design education; E-assessment; Elearning; Virtual product development

Weight and cost reduction of the thermal management for traction batteries by using the DSM methodology - Luft, Thomas; Klein, Florian; Wartzack, Sandro (Proceedings of the DESIGN 2014, 2014)
This paper provides a methodology to reduce weight and costs of thermal management systems for traction batteries in vehicles by using value engineering approaches and a matrix-based product description. This allows product developers to analyze and to improve the complex dependencies and relationships between all requirements, functions, properties and characteristics of the product as well as the respective associated costs and weights. This methodology is used and validated in the contribution for a simplified sealing plate of one cell module.
UnivIS-Import:2015-04-16:Pub.2014.tech.FT.FT-KLMEFK.weight
Keywords: design optimization; matrix-based product description; DSM; lightweight design; cost reduction; decision making

Welche Bedeutung haben die Maschinenelemente (noch) im Internet der Dinge? - Tremmel, Stephan (Konstruktion, 2019)
Keywords: Maschinenelemente; smarte Maschinenelemente; virtuelle Sensoren

Welches Wissensmanagement-System passt zum Unternehmen? - Luft, Thomas; Frey, Dennis; Wartzack, Sandro (Wissensmanagement - Magazin für Führungskräfte, 2014)
• Die Software für einen effizienten Umgang mit Wissen muss auf die Organisation zugeschnitten sein. • Ein Evaluationsprozess zur Auswahl eines geeigneten Wissensmanagementsystems (WMS) erleichtert die Entscheidungsfindung. • Ein WMS muss gewisse funktionale Anforderungen erfüllen, um organisatorisches Lernen und organisatorische Effektivität zu gewährleisten.
Keywords: IT-Systeme; IT-Tools; Software-Auswahl

What does Design for Production mean? – From Design Guidelines to Self-learning Engineering Workbenches - Wartzack, Sandro; Sauer, Christopher; Küstner, Christof (Proceedings of the 11th International Workshop on Integrated Design Engineering, 2017)
Today, product developers are highly interested in designing and assembling lightweight parts, which subsequently leads to the development of new manufacturing technologies. In order to evaluate their designs, product developers depend on manufacturing knowledge. In the last decades the manufacturing knowledge has been shared as design guidelines. But, there are no guidelines for new manufacturing technologies. To face this challenge, we started with a mathematical description of the product’s properties (metamodels) by means of data mining methods. The data has been acquired by scientists for manufacturing technologies in experimental and numerical parameter studies. We utilized the metamodels in a knowledge-based design synthesis, which is based on evolutionary multi-objective optimization. Finally, we present an answer to the question of what “Design for Production” in context of new manufacturing technologies really means.
Keywords: design for X; self-learning; data mining; Pareto-optimal design

What should a metabolic energy model look like? Sensitivity of metabolic energy model parameters during gait - Gambietz, Markus; Nitschke, Marlies; Miehling, Jörg; Koelewijn, Anne (9th World Congress of Biomechanics 2022 Taipei, 2022)
Introduction Many experimental [1] and simulation [2] studies have shown that metabolic energy is minimized in human movement. This makes metabolic energy an important variable in movement studies, e.g. to assess the quality of a prosthesis. The measurement of metabolic energy consumption is time-consuming and associated with methodological limitations, while metabolic energy models could estimate it from kinematic and kinetic variables of a single gait cycle [3]. However, there is currently only limited validation of the empirically chosen model parameters. Different metabolic energy models with different levels of complexity exist, while it is unclear whether increased complexity, i.e. more input parameters, are beneficial. Here, we compared different levels of complexity using pseudo-optimized models based on Monte-Carlo (MC) simulation investigate the benefit of the additional complexity. Methods We performed a MC simulation on the empirical parameters of seven metabolic energy models (see [4]). We used a gait dataset with optical motion capturing and indirect calorimetry recordings from 12 participants at three inclines and two speeds [5]. We ranked the parameters according to their resulting sensitivity indices. Further, optimized metabolic models were obtained. Results The original metabolic models resulted in a root mean square error (RMSE) of 1.00 to 2.45 J/(kg*m) for the data set. In the MC simulation, the RMSE was reduced to 0.75 J/(kg*m) for the best performing model (Bhargava, 2004 [6]), while the differences between the models were small. Among all pseudo-optimized metabolic models, negative metabolic rates of muscles were observed for the best fits, although this would not be biologically possible [7]. We investigated the necessity of several relationships that were common between the different metabolic models, namely muscle-length dependencies, fiber-type differentiation and activation-time thresholding. Muscle-length dependencies and activation heat rate fiber-type distinction mostly showed high sensitivity indices. On the other hand, fiber-type distinction in the maintenance heat rate as well as the muscle activation-time dependencies turned out to be mostly non-significant (p>0.05) in this dataset. Discussion We showed that highly complex metabolic energy expenditure models only provide little advantage over simpler metabolic energy expenditure models using MC simulation. Specifically, we found that activation-time dependency was ranked low in terms of sensitivity, which could therefore be omitted in metabolic energy models. We also found that negative metabolic rates yielded more accurate results. These results could be explained by the shortcomings of the Hill model, which, for example, overlooks the role of titin [8,9]. In the future, assuming more data and better personalized musculoskeletal models exist, a deep-learning based metabolic model could be an alternative to the current metabolic models. Acknowledgements This work was funded by the DFG: SFB 1483 – Project-ID 442419336. References [1] Hatze, Buys (1977). Biological Cybernetics, (27):9–20. [2] Srinivasan, Ruina (2006). Nature, 439(7072), 72-75. [3] Miller (2014). J. Biomech., 47(6):1373-81. [4] Koelewijn et al. (2019). PLOS ONE 14(9):e0222037. [5] Koelewijn et al. (2018). Zenodo: 10.5281/zenodo.1973799. [6] Bhargava et al. (2004). J. Biomech., 37(1):81–88. [7] Woledge et al. (2003). Adv. Exp. Med. Biol., 538:627–34. [8] Kiisa et al. (2012). Proceedings. Biological sciences, 279(1730):981–990. [9] Winter (2009). Wiley, Hoboken, N.J, 4th ed. <br
Keywords: Metabolic Cost; Monte Carlo Simulation; Sobol sequence; Sensitivity Analysis

What’s more important for product design – usability or emotionality? An examination of influencing factors - Buker, Tina; Schmitt, Teresa; Miehling, Jörg; Wartzack, Sandro (Journal of Engineering Design, 2022)
Usability and emotionality are fundamental aspects of user experience. However, the actual creation of an equally usable and emotionally appealing product design is still challenging for product developers, not least because of competing objectives during such equal consideration of both aspects. In order to make a user-oriented decision between a more usable or more emotional product design, product developers need a profound understanding of what matters to the user in different usage situations. By conducting 22 semistructured interviews, we contribute to this aim by identifying and examining factors that influence a user’s perceived importance of usability and emotionality in product design. In total, 29 influencing factors were identified with the purpose of use, the type of product and other people’s attitudes towards a product being most relevant or both emotionality and usability. Nine influencing factors from the literature were additionally examined in terms of their strength and direction in which they influence the importance of emotionality and usability. Hereby, considerable differences within individual expressions of the influencing factors were revealed. Furthermore, the perceived importance of emotionality varied much more than that of usability.<br
Keywords: Usability; emotional design; user experience; user-centred design; interview

What the Statistics Tell Us—How to Use Empiric Data in Design for Emotional Impressions - Kett, Susan; Schmitt, Benedikt; Wartzack, Sandro (Research into Design for Communities, Volume 2, 2017)
Looking at technical consumer products like communication devices or pc accessory, we state high saturated markets in developed societies. This leads to a broad range of market offers not only in performance or financial aspects. The users seek for more individual products that differentiate on a subsequent, more qualitative level. User centered design approaches have been developed to handle the resulting high product variety and to keep them economically efficient. E.g., Universal Design supports the development of products for as many persons as possible, also including those with physiological or cognitive deficits. But to really raise the quality of life we also need to take other needs into account. Maslow’s hierarchy of needs states that with the fulfilment of physical needs the level shifts to psychological demands like emotional or attitudinal satisfaction. We will shortly introduce a framework that supports an emotional design optimization based on interdisciplinary findings (e.g. psychology, market research or Kansei Engineering) and statistical data analysis. For a valid forecasting, robust and transparent mathematical treatment of this data is required. To this, we give a first overview of possible approaches and their potential to ensure robust and transparent mathematical data treatment in design for emotional impressions.
Keywords: Emotional engineering; Kansei engineering; User segmentation

Wissensbasierte Navigation für die lärmreduzierte Auslegung rotierender Maschinen in der Produktentwicklung - Küstner, Christof; Wartzack, Sandro (Design for X - Beiträge zum 25. DfX-Symposium, 2014)
Today, product developer face the challenge taking not only the requirements for mechanical properties of a product into account, but also other requirements like the acoustical properties, for instance. The problem is that important product properties like the acoustical properties are only revealed in the later development phases. Normally product developers elicit knowledge from experts to fulfil these additional requirements. In this contribution, an approach for a knowledge-based navigation for the development of noise-reduced machines is presented. Therefore the knowledge identification, acquisition, formalization and the implementation in an assistant system are described. This approach contributes to the improvement of knowledge transfer from expert to product developer vice versa.
UnivIS-Import:2015-10-26:Pub.2014.tech.FT.FT-KLMEFK.wissen
Keywords: knowledge-based navigation; assistant system; noise-reduced development; activities and decisions

Wissensbasierter Aufbau konstruktionsbegleitender Finite-Elemente-Analysen durch ein FEA-Assistenzsystem - Kestel, Philipp; Wartzack, Sandro (Entwerfen Entwickeln Erleben – Beiträge zu virtuellen Produktentwicklung und Konstruktionstechnik, 2016)
Finite-Elemente-Analyse (FEA) gewinnen in der Produktentwicklung zunehmend an Bedeutung.Für eine effiziente Nutzung der FEA muss diese jedoch frühzeitig in der Produktentwicklung angewendet werden. Darüber hinaus wird für einen erfolgreichen Einsatz umfangreiches Expertenwissen vorausgesetzt. Dieses Wissen konzentriert sich in den Unternehmen hauptsächlich auf erfahrene Berechnungsingenieure, die aufgrund zeitlicher Engpässe Simulationen meist nur zur Nachrechnung bereits ausdetaillierter Produktmodelle durchführen.Konstruktionsbegleitende Simulationen werden hingegen zu selten eingesetzt oder sind nicht aussagekräftig genug, wenn diese nicht von Berechnungsexperten erstellt werden. Vor diesem Hintergrund wir ein FEA-Assistenzsystem entwickelt, durch das weniger erfahrener Simulationsanwender, wie Konstruktionsingenieure, unterstützt und die Erstellung aussagekräftiger, strukturmechanischer Simulationen automatisiert wird.

Wissensbasierte und berechnungsunterstützte Konzeptabsicherung in den frühen Phasen der Produktentwicklung am Beispiel des Elektromotors - Tüchsen, Johann; Richter, Michael; Heydenreich, Johannes; Koch, Matthias; Schleich, Benjamin; Wartzack, Sandro (2018)
In order to prevent costs and unneeded effort in product development, design verifications in early development phases are used to identify non-suitable designs and errors. Therefore, this contribution proposes a concept for a completely automated design check based on simplified one-dimensional calculations including knowledge-based correction factors optimized for electric drives. Using knowledge-based systems (KBS) structure in combination with compiled template computer scripts, a very fast and multidisciplinary solution is given to evaluate the suitability of the created solution regarding the requirements. Additionally this concept is expandable for additional modules or motors and easy to maintai
Keywords: Konzeptabsicherung; Knowledge-based Systems; KBS; analytische Modelle

Zur Notwendigkeit eines konstruktionsmethodischen Ansatzes für die zeitfeste Auslegung endlosfaserverstärkter Kunststoffbauteile - Hartwich, Tobias S.; Völkl, Harald; Franz, Michael; Witzgall, Christian; Krause, Dieter; Wartzack, Sandro (Design for X - Beiträge zum 30. DfX-Symposium, 2019)
Efficient and systematic design methods are indispensable aids on the way to effective lightweight solutions. In this article, the necessity of providing the product developer with a design method for the design of endless fibre-rein-forced plastic (FRP) components to fulfil fatigue requirements is highlighted. Existing damage models and test methods could be used and extended within such approaches. A suitable method should take into account particularly the variety of requirements for FRP components and consider other influences, e.g. from multi-layer composite design or load introduction, preferably sup-ported by CAE tools. The simple applicability of an effective approach should be demonstrated both on test specimens and on demonstrator components.<br
Keywords: Lightweight Design; Fibre-reinforced plastics; Fatigue; Design methods

Zustandsdiagnose von Maschinen im Kontext von Industrie 4.0 unter Einsatz von Data-Mining Methoden - Küstner, Christof; Mitsch, Jürgen; Hegwein, Matthias; Meintker, Nico; Mönks, Konrad; Fröhlich, Moritz; Wartzack, Sandro (Design for X - Beiträge zum 27. DfX-Symposium, 2016)
Today, the machine industry offers a range of After-Sales-Services, including the installation and commissioning of the purchased products, the provision of spare parts, inspections or comprehensive maintenance contracts. Studies prove that After-Sales-Services often generate revenues that are several times higher than the original purchase price, which is why these services significantly contribute to a company's balance sheet. Worldwide operation of machines could lead to long machine downtimes before service technicians reach the operating site. Therefore, companies are interested in machine prognostics and predictive maintenance techniques. To accomplish this, an approach for condition-based maintenance in context of the internet of things and the use of data mining is presented in this contribution.
Keywords: condition-based maintenance; machine prognostics; internet of things; data mining

転がり軸受部品における圧縮残留応力とその寿命に及ぼす影響の計算と実験的研究 (Deutsch: Rechnerische und experimentelle Untersuchung des Einflusses von Druckeigenspannungen in Wälzlagerkomponenten und deren Auswirkung auf die Lebensdauer) - Pabst, Alexander; Tremmel, Stephan; Wartzack, Sandro (Machine design, 2018)
Reibungsreduzierung und Leistungsverdichtung im Antriebsstrang von Fahrzeugen stellen einen aktiven beitrag zur CO2-Reduzierung dar. In der konsequenten Optimierung und Verwendung von reibungsarmen Wälzlagern im Antriebsstrang besteht ein großes Potential zur Effizienzsteigerung. Eine weitere Möglichkeit stellt das Downsizing von Wälzlagern dar. Aus dem Einsatz von kleineren und leichteren Wälzlagern resultieren im Anwendungsfall geringere Verlustleistungen. Es ist jedoch zu berücksichtigen, dass gleichzeitig die Tragfähigkeit des Lagers reduziert wird. Aus diesem Grund ist für eine reibungsreduzierte Ausführung die Steigerung der Ermüdungslebensdauer durch zusätzliche Werkstoff-, Wärmebehandlungs- oder Bearbeitungsmaßnahmen notwendig. Basierend auf diesem Ansatz setzt sich dieser Beitrag mit gezielt eingebrachten Druckeigenspannungen im wälzbeanspruchten Werkstoffbereich von Wälzlagerkomponenten zur Lebensdauersteigerung, am Beispiel von Planetenbolzen, auseinander. Es werden Ergebnisse aus Wälzlagerlebensdauerversuchen unter dem Einfluss von Druckeigenspannungen und den damit verbundenen Lebensdauersteigerungen präsentiert. Begleitend dazu werden die herstellseitig eingebrachten Druckeigenspannungen mit Hilfe einer Variante der Schubspannungsintensitätshypothese und durch Lebensdauermodelle rechnerisch bewertet. Das Ziel ist die Berücksichtigung solcher Eigenspannungen bei der Auslegung von Wälzlagern für unterschiedliche Anwendungsfälle
Keywords: Wälzlager; Druckeigenspannung; Verfestigung; Lebensdauer; Ermüdung

Simulation-Based Virtual Validation of Functional Limiting Positions - Ehlert, Matthias; Stockinger, Andreas (Research in Tolerancing, 2024)
In addition to a classical toleration of components and assemblies, Computer-Aided Tolerancing became an indispensable engineering discipline in recent years—especially in the context of a series manufacturing of a product. Taking 3D geometries, resulting lever ratios, assembly sequences and various reference systems as well as statistical approaches into account, it already enables complex tolerance calculations of products that are subject to variations arising from the manufacturing process. One of the main premises for these kinds of simulations refers to the presumed rigid behavior of all contributors. As a direct consequence of that assumption this chapter describes a virtual approach, based on specified Key Product Characteristics that takes both elasticities and a possible non-linear system behavior in the simulation into consideration. This proceeding to include materialities and interactions between tolerance affected components increases the forecast quality of the tolerance simulation in terms of a more realistic prediction. The demonstrator used is the entry area of an automobile, where the tightness of the system against water, dust, or other media needs to be ensure

Tolerances in Mechanisms - Husch, Julia; Walter, Michael S.J. (Research in Tolerancing, 2024)
The development of mechanisms is challenging due to the highly time-dependent key characteristics and the occurring random and systematic deviations. An integrated tolerance analysis-optimization-synthesis approach to cope with these challenges during the product development is presented. This approach is not limited to a pure functional tolerance analysis and optimization, in fact it also builds a bridge to economical evaluations and optimizations so that at the end a cost-optimal tolerance specification for a mechanism can be achieved. At the beginning of the chapter, the challenges related to mechanisms are highlighted, especially the time-dependent behavior of a mechanism during its operation and the different deviations occurring during the production and the operation of the mechanism. After that, the integrated approach for the statistical tolerance analysis of mechanisms is described, starting from the classic tolerance analysis of static assemblies and successively enlarging it to an integrated tolerance analysis approach for mechanisms taking into account different kinds of deviations. Based on the integrated analysis approach, the economical evaluation of the tolerance specification by the Walter-Hiller diagram, the functional and cost related optimization and the visualization by Tol/Mech—insight are presented. At the end, the applicability is demonstrated in a case stud