@article{63391, abstract = {{This study addresses the challenge of insufficient weld penetration in the outer thin low-carbon steel during resistance spot welding of three-layer dissimilar stack-ups containing advanced high-strength steels. To overcome thermal imbalance constraints, an innovative strategy leveraging plastic shell containment is proposed to elevate the expulsion-free heat input threshold. By applying a combined preheating and ramping current profile, a coordinated “shell-first, nugget-second” sequence is achieved. This mechanism creates a solid-state barrier prior to rapid fusion, effectively preventing expulsion. Experimental results demonstrate that while the reference constant-current schedule fails to maintain a process window under a 2 mm initial gap (IG) disturbance, the proposed strategy significantly enhances process stability. It increases the maximum expulsion-free heat input by 24 % (to 6338 J) under normal conditions and by 77 % (to 6482 J) under the IG condition. Crucially, the increased heat input drives nugget growth across all interfaces, achieving a penetration depth of 0.38 mm (48 % penetration ratio) in the low-carbon steel sheet under the gap condition. These findings validate the strategy’s effectiveness in ensuring weld quality and robustness, which is further confirmed by its transferability to a lowerresistivity DX54D cover sheet.}}, author = {{Yang, Keke and Männer, Leonhard and Wang, Zhuoqun and Olfert, Viktoria and Böhm, Yannic and Hein, David and Meschut, Gerson}}, issn = {{1526-6125}}, journal = {{Journal of Manufacturing Processes}}, number = {{Special issue entitled: ‘Trends on spot joining’ published in Journal of Manufacturing Processes.}}, pages = {{984--1000}}, publisher = {{Elsevier BV}}, title = {{{Process window expansion with transferable applicability in three-layer dissimilar steel resistance spot welding via expulsion prevention}}}, doi = {{10.1016/j.jmapro.2025.12.036}}, volume = {{157}}, year = {{2026}}, } @article{63418, abstract = {{Manufacturing tolerances have a measurable influence on the structural integrity of self-piercing riveted (SPR) joints in automotive applications, yet their quantitative impact on load-bearing behavior remains insufficiently resolved. This study establishes a validated hierarchical methodology to predict tolerance-dependent failure behavior of SPR joints, progressing from coupon to sub-component scale through an integrated experimental–numerical approach. Five critical manufacturing tolerances, including rivet length (±0.5 mm), rivet head position (±0.3 mm), orthogonality deviation (2.8° and 5°), lateral offset (up to 1.2 mm), and flange overlap reduction (up to 7.5 mm), were investigated. Steel–steel joints exhibited a higher sensitivity to tolerances by a factor of 2–3 compared to steel–aluminum joints. A unified effective rivet length concept was developed to consolidate the geometric effects of all tolerances into a single physically meaningful parameter, enabling load-bearing capacity prediction with R2 > 0.95 across all evaluated loading directions. The sub-component validation employing T-joint specimens indicates a 2–3 fold amplification of tolerance effects at critical structural regions, providing experimental evidence for the hierarchical scaling principle. The methodology was implemented in a tolerance-dependent CONSTRAINED_SPR3 formulation, providing >99 % computational efficiency improvement while maintaining a deviation in maximum force prediction within ±7 %. This framework enables the physically consistent representation of manufacturing variation within large-scale simulations and establishes a transferable basis for tolerance-resilient virtual vehicle development.}}, author = {{Olfert, Viktoria and Yang, Keke and Rochel, Philip and Bähr, Philipp and Hein, David and Sommer, Silke and Meschut, Gerson}}, issn = {{1526-6125}}, journal = {{Journal of Manufacturing Processes}}, number = {{Special issue entitled: ‘Trends on spot joining’ published in Journal of Manufacturing Processes.}}, pages = {{1250--1273}}, publisher = {{Elsevier BV}}, title = {{{Predictive modeling of tolerance-dependent failure behavior of self-pierce riveted joints: From coupon-level tests to sub-component validation}}}, doi = {{10.1016/j.jmapro.2025.12.058}}, volume = {{157}}, year = {{2026}}, } @article{58535, author = {{Yang, Keke and Wang, Zhuoqun and Haak, Viktor and Olfert, Viktoria and El-Sari, Bassel and Hein, David and Biegler, Max and Rethmeier, Michael and Meschut, Gerson}}, issn = {{1526-6125}}, journal = {{Journal of Manufacturing Processes}}, pages = {{306--319}}, publisher = {{Elsevier BV}}, title = {{{A novel welding schedule for expanding the expulsion-free process window in resistance spot welding of dissimilar joints with ultra-high strength steel}}}, doi = {{10.1016/j.jmapro.2025.02.009}}, volume = {{137}}, year = {{2025}}, } @article{61526, author = {{Olfert, Viktoria and Bähr, Philipp and Schuster, Lilia and Westhoff, Julia and Yang, Keke and Ibeski, Enes and Hein, David and Sommer, Silke and Meschut, Gerson}}, journal = {{Journal of Manufacturing Processes}}, pages = {{311--331}}, publisher = {{Elsevier}}, title = {{{Failure behavior prediction for resistance spot-welded three-layered dissimilar joints with advanced high-strength steel}}}, doi = {{https://doi.org/10.1016/j.jmapro.2025.09.077}}, volume = {{154}}, year = {{2025}}, } @inproceedings{59091, abstract = {{Abstract. Liquid Metal Embrittlement (LME) cracking is a well-documented issue encountered during resistance spot welding (RSW) of zinc-coated advanced high-strength steels (AHSS) in automotive manufacturing. Given that existing research has predominantly focused on laboratory-scale samples and lacks investigation into the load-bearing capacity of joints under crash conditions, this study aims to fill these gaps by analyzing third-generation zinc-coated AHSS. S-Rail components were produced through stamping to replicate real-world manufacturing conditions and geometries of automotive parts. To account for the disturbances typically encountered in production, samples with LME cracks were intentionally fabricated. Subsequently, a modified three-point bending test, assisted by numerical simulations, was developed to effectively apply loads to the weld spots of the S-Rail components. Results from crash tests demonstrated that observed light crack severity does not significantly compromise the joint's load-bearing capacity or lead to earlier joint failure.}}, author = {{Yang, Keke and Biegler, Max and Happe, Linus and Striewe, Marius and Olfert, Viktoria and Hein, David and Rethmeier, Michael and Meschut, Gerson}}, booktitle = {{Materials Research Proceedings}}, issn = {{2474-395X}}, publisher = {{Materials Research Forum LLC}}, title = {{{Influence of Liquid metal embrittlement on load-bearing capacity of resistance spot welds under crash loads: A study based on S-Rail components}}}, doi = {{10.21741/9781644903551-42}}, volume = {{52}}, year = {{2025}}, } @inproceedings{60604, abstract = {{Abstract. In the field of online condition monitoring, non-destructive testing methods using active acoustic testing [1] emerged as innovative tools. These techniques are particularly effective because damage in joined structures leads to significant changes in their vibrational characteristics. However, the consistent use of online condition monitoring through active acoustic testing combined with complex pattern recognition for early crack detection in joined components has not yet been fully established. This research aims to develop an online crack detection system employing pattern recognition techniques under cyclic loading during fatigue tests, utilizing non-contact active acoustic testing with laser vibrometry. Due to the wide range of materials that can be joined, mechanical joining processes can be used in many different industry branches. Self-pierce riveting (SPR), in particular, is a well-established joining process. Therefore, the investigations for online crack detection initially focus on SPR joints. To achieve this, the fatigue behavior of SPR joints in a lap-shear configuration was characterized. Experimental fatigue testing demonstrated that SPR joint failure occurs either through cracks propagating in the sheet material away from the rivet or in the rivet foot, depending on the material combination. Laser vibrometry has been successfully used as a crack detection system and has proven to be effective in detecting crack initiation in SPR joints. Cracks can be detected without contact regardless of the material combination, the damage location, the size of the damage, or the type of damage. The optimization of the crack detection system involved several key enhancements, including adjusting data acquisition to improve crack detection, incorporating principal component analysis (PCA) to reduce dimensionality, and implementing a classification model based on a global training dataset. An intuitive, problem-specific software demonstrator for analyzing the crack initiation behavior of SPR joints under cyclic loading was developed and iteratively optimized. Future work will focus on the implementation of an autoencoder network to further enhance crack detection capabilities.}}, author = {{Olfert, Viktoria and Yang, Keke and Gollnick, Maik and Krause, Jacob and Hein, David and Meschut, Gerson}}, booktitle = {{Materials Research Proceedings}}, issn = {{2474-395X}}, publisher = {{Materials Research Forum LLC}}, title = {{{Analysis of fatigue behaviour of self-piercing riveted joints under cyclic loading using laser vibrometry}}}, doi = {{10.21741/9781644903599-154}}, volume = {{54}}, year = {{2025}}, } @article{50726, abstract = {{Resistance spot‐welded joints containing press‐hardened steels are seen to exhibit a fracture mode called total dome failure, where the weld nugget completely separates from one steel sheet along the weld nugget edge. The effect of weld nugget shape and material property gradients is studied based on damage mechanics modeling and experimental validation to shed light on the underlying influencing factors. For a three‐steel‐sheet spot‐welded joint combining DP600 (1.5 mm)–CR1900T (1.0 mm)–CR1900T (1.0 mm), experiments under shear loading reveal that fracture occurs in the DP600 sheet along the weld nugget edge. In subsequent numerical simulation studies with damage mechanics models whose parameters are independently calibrated for every involved material configuration, three variations of the geometrical joint configuration are considered—an approximation of the real joint, one variation with a steeper weld nugget shape, and one variation with a less pronounced gradient between weld nugget material and heat‐affected zone material properties. The results of the finite‐element simulations show that a shallower weld nugget and a more pronounced material gradient lead to a faster increase of plastic strain at the edge of the weld nugget and promote the occurrence of total dome failure.}}, author = {{Schuster, Lilia and Olfert, Viktoria and Sherepenko, Oleksii and Fehrenbach, Clemens and Song, Shiyuan and Hein, David and Meschut, Gerson and Biro, Elliot and Münstermann, Sebastian}}, issn = {{1611-3683}}, journal = {{steel research international}}, keywords = {{Materials Chemistry, Metals and Alloys, Physical and Theoretical Chemistry, Condensed Matter Physics}}, publisher = {{Wiley}}, title = {{{Influences of Weld Nugget Shape and Material Gradient on the Shear Strength of Resistance Spot‐Welded Joints}}}, doi = {{10.1002/srin.202300530}}, year = {{2024}}, } @inproceedings{58382, author = {{Striewe, Marius and Bähr, Philipp and Meschut, Gerson and Hein, David and Sommer, Silke}}, booktitle = {{14. Kolloquium: Gemeinsame Forschung in der Mechanischen Fügetechnik}}, title = {{{Ersatzmodellentwicklung zur Berücksichtigung der lokalen Fügeelementkinematik in mechanisch gefügten Verbindungen für die Bauteilauslegung im stahlintensiven Karosseriebau}}}, year = {{2024}}, } @article{57311, author = {{Yang, Keke and Sowada, Matthias and Olfert, Viktoria and Seitz, Georg and Schreiber, Vincent and Heitmann, Marcel and Hein, David and Biegler, Max and Jüttner, Sven and Rethmeier, Michael and Meschut, Gerson}}, issn = {{2238-7854}}, journal = {{Journal of Materials Research and Technology}}, publisher = {{Elsevier BV}}, title = {{{Influence of liquid metal embrittlement on the failure behavior of dissimilar spot welds with advanced high-strength steel: A component study}}}, doi = {{10.1016/j.jmrt.2024.11.166}}, year = {{2024}}, } @inproceedings{52688, author = {{Bähr, Philipp and Striewe, Marius and Meschut, Gerson and Sommer, Silke and Hein, David}}, booktitle = {{13. Kolloquium: Gemeinsame Forschung in der Mechanischen Fügetechnik}}, title = {{{Ersatzmodellentwicklung zur Berücksichtigung der lokalen Fügeelementkinematik in mechanisch gefügten Verbindungen für die Bauteilauslegung im stahlintensiven Karosseriebau}}}, year = {{2023}}, } @inbook{52689, author = {{Striewe, Marius and Teutenberg, Dominik and Hein, David and Meschut, Gerson and Schmelzle, Lars and Mergheim, Julia and Possart, Gunnar}}, booktitle = {{Klebtechnische Doktorandenseminare 2020 - 2022}}, isbn = {{978-3-96144-139-6}}, location = {{Blankenburg (Harz)}}, title = {{{Methode zur Simulation des temperaturabhängigen Crashverhaltens von strukturellen Klebverbindungen}}}, volume = {{369}}, year = {{2023}}, } @inproceedings{50727, abstract = {{Die aktuellen politischen und wirtschaftlichen Rahmenbedingungen zur Reduzierung der CO2-Emissionen sowie der Trend zur flächendeckenden Elektromobilität führen zu einer Vielzahl an neuen Herausforderungen für die Auslegung zukünftiger Fahrzeugkonzepte. Eine besondere Herausforderung ist das durch die Batterie ins Fahrzeug eingebrachte Zusatzgewicht. Hierdurch ergibt sich ein Konflikt zu der bestehenden Kundenerwartung nach einer hohen Reichweite. Durch den umfangreichen Einsatz von höchstfesten Stählen in dünnen Blechdicken im Karosseriebau soll die Reduzierung des Gesamtfahrzeuggewichts vorangetrieben werden. Vor allem im stahlintensiven Leichtbau ist das Widerstandspunktschweißen aufgrund des hohen Automatisierungsgrads, der Prozesssicherheit und der damit verbundenen Wirtschaftlichkeit das dominierende Fügeverfahren. Um Begrenzungen des Bauraums der Karosserie zu begegnen und um den Materialeinsatz im Leichtbau möglichst effizient zu gestalten, werden mehrschnittige Punktschweißverbindungen eingesetzt. Hieraus ergeben sich neue Herausforderungen für die Vorhersage des Trag- und Versagensverhaltens unter Crashbelastung. Dieser Beitrag stellt eine systematische Charakterisierung von 3-Blechverbindungen zur Auffindung von formelmäßigen, empirischen Zusammenhängen zwischen der Festigkeit der Verbindung und den Einflussgrößen vor. Nach der Identifikation geeigneter Einflussgrößen, wie zum Beispiel Blechfestigkeit, Blechanordnung, Blechdickenkombination sowie Belastungsart und Lasteinleitung, auf das Trag- und Versagensverhalten, werden numerische Simulationen durchgeführt, um Ursachen für auftretende Phänomene aus den experimentellen Ergebnissen aufzuklären. Weiterhin wird untersucht, inwieweit das Verhalten von 2-Blechverbindungen auf 3-Blechverbindungen übertragbar ist. Die gefundenen Zusammenhänge sollen schnelle und kostengünstige Abschätzungen über die Festigkeit von 3-Blechbverbindungen ermöglichen. Darüber hinaus werden Ersatzmodelle für die Crashsimulation von 3-Blechverbindungen entwickelt, die recheneffizient für die Sicherheitsbewertung von großen, geschweißten Bauteilen eingesetzt werden können. Dabei sollen insbesondere die Einflüsse des Lastangriffs an jeweils einer oder beiden Fügebenen auf die Festigkeit und Energieabsorption unter verschiedenen Belastungen wie Zug, Scherung sowie Biegung abbildbar sein. }}, author = {{Olfert, Viktoria and Schuster, Lilia and Bähr, Philipp and Hein, David and Meschut, Gerson and Sommer, Silke}}, location = {{Duisburg}}, title = {{{Methodenentwicklung zur Prognose des Crashverhaltens von widerstandspunktgeschweißten 3-Stahlblechverbindungen}}}, year = {{2023}}, } @article{33002, abstract = {{Many mechanical material properties show a dependence on the strain rate, e.g. yield stress or elongation at fracture. The quantitative description of the material behavior under dynamic loading is of major importance for the evaluation of crash safety. This is carried out using numerical methods and requires characteristic values for the materials used. For the standardized determination of dynamic characteristic values in sheet metal materials, tensile tests performed according to the guideline from [1]. A particular challenge in dynamic tensile tests is the force measurement during the test. For this purpose, strain gauges are attached on each specimen, wired to the measuring equipment and calibrated. This is a common way to determine a force signal that is as low in vibration and as free of bending moments as possible. The preparation effort for the used strain gauges are enormous. For these reasons, an optical method to determine the force by strain measurement using DIC is presented. The experiments are carried out on a high speed tensile testing system. In combioantion with a 3D DIC high speed system for optical strain measurement. The elastic deformation of the specimen in the dynamometric section is measured using strain gauges and the optical method. The measured signals are then compared to validate the presented method. The investigations are conducted using the dual phase steel material HCT590X and the aluminum material EN AW-6014 T4. Strain rates of up to 240 s-1 are investigated.}}, author = {{Böhnke, Max and Unruh, Eduard and Sell, Stanislaw and Bobbert, Mathias and Hein, David and Meschut, Gerson}}, issn = {{1662-9795}}, journal = {{Key Engineering Materials}}, keywords = {{Mechanical Engineering, Mechanics of Materials, General Materials Science}}, location = {{Braga, Portugal}}, pages = {{1564--1572}}, publisher = {{Trans Tech Publications, Ltd.}}, title = {{{Functionality Study of an Optical Measurement Concept for Local Force Signal Determination in High Strain Rate Tensile Tests}}}, doi = {{10.4028/p-wpuzyw}}, volume = {{926}}, year = {{2022}}, } @article{34459, author = {{Schmelzle, Lars and Striewe, Marius and Mergheim, Julia and Meschut, Gerson and Possart, Gunnar and Teutenberg, Dominik and Hein, David and Steinmann, Paul}}, issn = {{0169-4243}}, journal = {{Journal of Adhesion Science and Technology}}, keywords = {{Materials Chemistry, Surfaces, Coatings and Films, Surfaces and Interfaces, Mechanics of Materials, General Chemistry}}, title = {{{Testing, modelling, and parameter identification for adhesively bonded joints under the influence of temperature}}}, doi = {{10.1080/01694243.2022.2125714}}, year = {{2022}}, } @inproceedings{35947, abstract = {{The recent trend towards extensive electric mobility leads to a variety of new challenges for the engineering of future vehicle concepts. One particular challenge is the additional weight added to the vehicle by the battery, which stands in direct contrast to the existing customer expectation of a high driving range. The reduction of the total vehicle weight is driven by the extensive use of ultra-high-strength steels in thin sheet thicknesses in car body construction. Resistance spot welding is the dominant joining process in steel-intensive lightweight construction due to its high degree of automation, process reliability and the associated economic efficiency. In order to comply limitations of the space in the vehicle body and to ensure the most efficient use of materials in lightweight construction, joints are used that connect several sheets with a single spot weld. This leads to new challenges for the prediction of the load-bearing capacity and failure behaviour under crash loading. This paper presents a systematic characterisation of 3 sheet steel joints in order to find formulary, empirical relationships between the load-bearing capacity of the joint and the affecting parameters. Numerical simulations are carried out in order to clarify the causes of occurring phenomena in experiments. For this purpose, influencing variables such as joint strength, joint arrangement, sheet thickness, sheet strength, load type and load case on the load bearing capacity and failure behaviour are identified. Furthermore, the extent to which the behaviour of 2-sheet joints can be transferred to 3-sheet joints is investigated. A formulary correlation enables a quick and inexpensive estimates of the load-bearing capacity of 3-sheet metal connections. These models can be used for a computer-efficient simulation of components with three layered spot welded joints.}}, author = {{Olfert, Viktoria and Meschut, Gerson and Hein, David and Schuster, Lilia and Sommer, Silke}}, location = {{Mailand}}, publisher = {{SCT}}, title = {{{Development of a crash behaviour prediction method for resistance spot welded 3-steel sheet joints}}}, year = {{2022}}, } @inproceedings{31499, author = {{Olfert, Viktoria and Meschut, Gerson and Hein, David and Rochel, Philip and Sommer, Silke}}, location = {{Dresden}}, title = {{{Einfluss fertigungsbedingter Toleranzen auf das Versagens- und Verformungsverhalten mechanisch gefügter Verbindungen unter Crashbelastung}}}, year = {{2021}}, } @inproceedings{20852, author = {{Unruh, Eduard and Hein, David and Meschut, Gerson}}, booktitle = {{10. Fügetechnisches Gemeinschaftskolloquium}}, title = {{{Analytische Auslegung der Schwingfestigkeit geclinchter Verbindungen}}}, year = {{2020}}, } @inproceedings{20853, author = {{Bähr, Philipp and Sommer, Silke and Unruh, Eduard and Hein, David and Meschut, Gerson}}, title = {{{Charakterisierung und Modellierung von Kerbeffekten durch Mischverbindungen in Karosseriebauteilen aus höchstfesten Stählen}}}, year = {{2020}}, } @article{21508, author = {{Meschut, Gerson and Hein, David and Gerkens, Michael}}, issn = {{2351-9789}}, journal = {{Procedia Manufacturing}}, location = {{Leuven, Belgium}}, pages = {{280--287}}, title = {{{Numerical simulation of high-speed joining of sheet metal structures}}}, doi = {{10.1016/j.promfg.2019.02.173}}, year = {{2019}}, } @inproceedings{21510, author = {{Hein, David and Meschut, Gerson and Tümkaya, Gökhan}}, location = {{Bratislava}}, title = {{{Fatigue life investigation of resistance spot-welded dual-and complex-phase steels using the LWF-KS-II concept}}}, year = {{2019}}, }