[{"publication":"Proceedings of the 8th International Conference on Integrity-Reliability-Failure (IRF2025)","abstract":[{"text":"The use of continuous fiber-reinforced thermoplastics (FRTP) in automotive industry increases due to their excellent material properties and possibility of rapid processing. The scale spanning heterogeneity of their material structure and its influence on the material behavior, however, presents significant challenges for most joining technologies, such as self-piercing riveting (SPR). During mechanical joining, the material structure is significantly altered within and around the joining zone, heavily influencing the material behavior. A comprehensive understanding of the underlying phenomena of material alteration during the SPR process is essential as basis for validating numerical simulations. This study examines the material structure at ten stages of a step-setting test of SPR with two FRTP sheets with glass-fiber reinforcement. Utilizing X-ray computed tomography (CT), the damage phenomena within different areas of the setting test are analyzed three-dimensionally and key parameters are quantified. Dominating phenomena during the penetration of the rivet into the laminate are fiber failure (FF), interfiber failure (IFF) and fiber bending, while delamination, fiber kinking and roving splitting are also observed. At the final stages, the bottom layers of the second sheet collapse and form a bulge into the cavity of the die.","lang":"eng"}],"keyword":["self-piercing riveting","computed tomography","thermoplastic composites","process-structure-interaction"],"language":[{"iso":"eng"}],"year":"2025","publisher":"FEUP","date_created":"2025-09-08T11:52:45Z","title":"LOCAL DEFORMATION AND FAILURE OF COMPOSITES DURING SELF-PIERCING RIVETING: A CT BASED MICROSTRUCTURE INVESTIGATION","type":"conference","editor":[{"first_name":"J.F. Silva","full_name":"Gomes, J.F. Silva","last_name":"Gomes"},{"first_name":"Shaker A.","full_name":"Meguid, Shaker A.","last_name":"Meguid"}],"status":"public","_id":"61149","project":[{"_id":"133","name":"TRR 285 - Project Area C"},{"_id":"148","name":"TRR 285 - Subproject C04"},{"name":"TRR 285:  Methodenentwicklung zur mechanischen Fügbarkeit in wandlungsfähigen Prozessketten","_id":"130"},{"_id":"131","name":"TRR 285 - Project Area A"},{"_id":"137","name":"TRR 285 - Subproject A03"},{"_id":"135","name":"TRR 285 - Subproject A01"}],"user_id":"105344","publication_identifier":{"isbn":["9789727523238"]},"publication_status":"published","place":"Porto","citation":{"short":"A. Dargel, B. Gröger, M.C. Schlichter, J. Gerritzen, D. Köhler, G. Meschut, M. Gude, R. Kupfer, in: J.F.S. Gomes, S.A. Meguid (Eds.), Proceedings of the 8th International Conference on Integrity-Reliability-Failure (IRF2025), FEUP, Porto, 2025.","bibtex":"@inproceedings{Dargel_Gröger_Schlichter_Gerritzen_Köhler_Meschut_Gude_Kupfer_2025, place={Porto}, title={LOCAL DEFORMATION AND FAILURE OF COMPOSITES DURING SELF-PIERCING RIVETING: A CT BASED MICROSTRUCTURE INVESTIGATION}, DOI={<a href=\"https://doi.org/10.24840/978-972-752-323-8\">10.24840/978-972-752-323-8</a>}, booktitle={Proceedings of the 8th International Conference on Integrity-Reliability-Failure (IRF2025)}, publisher={FEUP}, author={Dargel, Alrik and Gröger, Benjamin and Schlichter, Malte Christian and Gerritzen, Johannes and Köhler, Daniel and Meschut, Gerson and Gude, Maik and Kupfer, Robert}, editor={Gomes, J.F. Silva and Meguid, Shaker A.}, year={2025} }","mla":"Dargel, Alrik, et al. “LOCAL DEFORMATION AND FAILURE OF COMPOSITES DURING SELF-PIERCING RIVETING: A CT BASED MICROSTRUCTURE INVESTIGATION.” <i>Proceedings of the 8th International Conference on Integrity-Reliability-Failure (IRF2025)</i>, edited by J.F. Silva Gomes and Shaker A. Meguid, FEUP, 2025, doi:<a href=\"https://doi.org/10.24840/978-972-752-323-8\">10.24840/978-972-752-323-8</a>.","apa":"Dargel, A., Gröger, B., Schlichter, M. C., Gerritzen, J., Köhler, D., Meschut, G., Gude, M., &#38; Kupfer, R. (2025). LOCAL DEFORMATION AND FAILURE OF COMPOSITES DURING SELF-PIERCING RIVETING: A CT BASED MICROSTRUCTURE INVESTIGATION. In J. F. S. Gomes &#38; S. A. Meguid (Eds.), <i>Proceedings of the 8th International Conference on Integrity-Reliability-Failure (IRF2025)</i>. FEUP. <a href=\"https://doi.org/10.24840/978-972-752-323-8\">https://doi.org/10.24840/978-972-752-323-8</a>","ama":"Dargel A, Gröger B, Schlichter MC, et al. LOCAL DEFORMATION AND FAILURE OF COMPOSITES DURING SELF-PIERCING RIVETING: A CT BASED MICROSTRUCTURE INVESTIGATION. In: Gomes JFS, Meguid SA, eds. <i>Proceedings of the 8th International Conference on Integrity-Reliability-Failure (IRF2025)</i>. FEUP; 2025. doi:<a href=\"https://doi.org/10.24840/978-972-752-323-8\">10.24840/978-972-752-323-8</a>","ieee":"A. Dargel <i>et al.</i>, “LOCAL DEFORMATION AND FAILURE OF COMPOSITES DURING SELF-PIERCING RIVETING: A CT BASED MICROSTRUCTURE INVESTIGATION,” in <i>Proceedings of the 8th International Conference on Integrity-Reliability-Failure (IRF2025)</i>, Porto, 2025, doi: <a href=\"https://doi.org/10.24840/978-972-752-323-8\">10.24840/978-972-752-323-8</a>.","chicago":"Dargel, Alrik, Benjamin Gröger, Malte Christian Schlichter, Johannes Gerritzen, Daniel Köhler, Gerson Meschut, Maik Gude, and Robert Kupfer. “LOCAL DEFORMATION AND FAILURE OF COMPOSITES DURING SELF-PIERCING RIVETING: A CT BASED MICROSTRUCTURE INVESTIGATION.” In <i>Proceedings of the 8th International Conference on Integrity-Reliability-Failure (IRF2025)</i>, edited by J.F. Silva Gomes and Shaker A. Meguid. Porto: FEUP, 2025. <a href=\"https://doi.org/10.24840/978-972-752-323-8\">https://doi.org/10.24840/978-972-752-323-8</a>."},"oa":"1","date_updated":"2026-02-27T06:45:17Z","author":[{"last_name":"Dargel","full_name":"Dargel, Alrik","id":"114764","first_name":"Alrik"},{"first_name":"Benjamin","last_name":"Gröger","full_name":"Gröger, Benjamin"},{"last_name":"Schlichter","id":"61977","full_name":"Schlichter, Malte Christian","first_name":"Malte Christian"},{"first_name":"Johannes","full_name":"Gerritzen, Johannes","id":"105344","orcid":"0000-0002-0169-8602","last_name":"Gerritzen"},{"last_name":"Köhler","full_name":"Köhler, Daniel","id":"83408","first_name":"Daniel"},{"orcid":"0000-0002-2763-1246","last_name":"Meschut","id":"32056","full_name":"Meschut, Gerson","first_name":"Gerson"},{"first_name":"Maik","last_name":"Gude","full_name":"Gude, Maik"},{"last_name":"Kupfer","full_name":"Kupfer, Robert","first_name":"Robert"}],"conference":{"location":"Porto","end_date":"2025-07-18","start_date":"2025-07-15","name":"8th International Conference on Integrity-Reliability-Failure (IRF2025)"},"doi":"10.24840/978-972-752-323-8","main_file_link":[{"open_access":"1","url":"https://www.researchgate.net/publication/395593556_LOCAL_DEFORMATION_AND_FAILURE_OF_COMPOSITES_DURING_SELF-PIERCING_RIVETING_A_CT_BASED_MICROSTRUCTURE_INVESTIGATION"}]},{"volume":3,"author":[{"first_name":"Johannes","id":"105344","full_name":"Gerritzen, Johannes","orcid":"0000-0002-0169-8602","last_name":"Gerritzen"},{"first_name":"Andreas","full_name":"Hornig, Andreas","last_name":"Hornig"},{"first_name":"Peter","full_name":"Winkler, Peter","last_name":"Winkler"},{"first_name":"Maik","last_name":"Gude","full_name":"Gude, Maik"}],"date_created":"2025-11-04T12:47:06Z","publisher":"European Society for Composite Materials (ESCM)","date_updated":"2026-02-27T06:46:21Z","doi":"10.60691/yj56-np80","title":"Direct parameter identification for highly nonlinear strain rate dependent constitutive models using machine learning","publication_identifier":{"isbn":["978-2-912985-01-9"]},"page":"1252–1259","intvolume":"         3","citation":{"chicago":"Gerritzen, Johannes, Andreas Hornig, Peter Winkler, and Maik Gude. “Direct Parameter Identification for Highly Nonlinear Strain Rate Dependent Constitutive Models Using Machine Learning.” In <i>ECCM21 - Proceedings of the 21st European Conference on Composite Materials</i>, 3:1252–1259. European Society for Composite Materials (ESCM), 2024. <a href=\"https://doi.org/10.60691/yj56-np80\">https://doi.org/10.60691/yj56-np80</a>.","ieee":"J. Gerritzen, A. Hornig, P. Winkler, and M. Gude, “Direct parameter identification for highly nonlinear strain rate dependent constitutive models using machine learning,” in <i>ECCM21 - Proceedings of the 21st European Conference on Composite Materials</i>, 2024, vol. 3, pp. 1252–1259, doi: <a href=\"https://doi.org/10.60691/yj56-np80\">10.60691/yj56-np80</a>.","ama":"Gerritzen J, Hornig A, Winkler P, Gude M. Direct parameter identification for highly nonlinear strain rate dependent constitutive models using machine learning. In: <i>ECCM21 - Proceedings of the 21st European Conference on Composite Materials</i>. Vol 3. European Society for Composite Materials (ESCM); 2024:1252–1259. doi:<a href=\"https://doi.org/10.60691/yj56-np80\">10.60691/yj56-np80</a>","apa":"Gerritzen, J., Hornig, A., Winkler, P., &#38; Gude, M. (2024). Direct parameter identification for highly nonlinear strain rate dependent constitutive models using machine learning. <i>ECCM21 - Proceedings of the 21st European Conference on Composite Materials</i>, <i>3</i>, 1252–1259. <a href=\"https://doi.org/10.60691/yj56-np80\">https://doi.org/10.60691/yj56-np80</a>","short":"J. Gerritzen, A. Hornig, P. Winkler, M. Gude, in: ECCM21 - Proceedings of the 21st European Conference on Composite Materials, European Society for Composite Materials (ESCM), 2024, pp. 1252–1259.","bibtex":"@inproceedings{Gerritzen_Hornig_Winkler_Gude_2024, title={Direct parameter identification for highly nonlinear strain rate dependent constitutive models using machine learning}, volume={3}, DOI={<a href=\"https://doi.org/10.60691/yj56-np80\">10.60691/yj56-np80</a>}, booktitle={ECCM21 - Proceedings of the 21st European Conference on Composite Materials}, publisher={European Society for Composite Materials (ESCM)}, author={Gerritzen, Johannes and Hornig, Andreas and Winkler, Peter and Gude, Maik}, year={2024}, pages={1252–1259} }","mla":"Gerritzen, Johannes, et al. “Direct Parameter Identification for Highly Nonlinear Strain Rate Dependent Constitutive Models Using Machine Learning.” <i>ECCM21 - Proceedings of the 21st European Conference on Composite Materials</i>, vol. 3, European Society for Composite Materials (ESCM), 2024, pp. 1252–1259, doi:<a href=\"https://doi.org/10.60691/yj56-np80\">10.60691/yj56-np80</a>."},"year":"2024","user_id":"105344","_id":"62078","project":[{"name":"TRR 285:  Methodenentwicklung zur mechanischen Fügbarkeit in wandlungsfähigen Prozessketten","_id":"130"},{"_id":"137","name":"TRR 285 - Subproject A03"},{"_id":"131","name":"TRR 285 - Project Area A"}],"language":[{"iso":"eng"}],"keyword":["Direct parameter identification","Machine learning","Convolutional neural networks","Strain rate dependency","Fiber reinforced plastics","woven composites","segmentation","synthetic training data","x-ray computed tomography"],"publication":"ECCM21 - Proceedings of the 21st European Conference on Composite Materials","type":"conference","status":"public","abstract":[{"lang":"eng","text":"Fiber reinforced plastics (FRP) exhibit strongly non-linear deformation behavior. To capture this in simulations, intricate models with a variety of parameters are typically used. The identification of values for such parameters is highly challenging and requires in depth understanding of the model itself. Machine learning (ML) is a promising approach for alleviating this challenge by directly predicting parameters based on experimental results. So far, this works mostly for purely artificial data. In this work, two approaches to generalize to experimental data are investigated: a sequential approach, leveraging understanding of the constitutive model and a direct, purely data driven approach. This is exemplary carried out for a highly non-linear strain rate dependent constitutive model for the shear behavior of FRP.The sequential model is found to work better on both artificial and experimental data. It is capable of extracting well suited parameters from the artificial data under realistic conditions. For the experimental data, the model performance depends on the composition of the experimental curves, varying between excellently suiting and reasonable predictions. Taking the expert knowledge into account for ML-model training led to far better results than the purely data driven approach. Robustifying the model predictions on experimental data promises further improvement. "}]},{"user_id":"7850","project":[{"name":"TRR 285: TRR 285","_id":"130","grant_number":"418701707"},{"_id":"133","name":"TRR 285 - C: TRR 285 - Project Area C"},{"_id":"148","name":"TRR 285 – C04: TRR 285 - Subproject C04"}],"_id":"34212","language":[{"iso":"eng"}],"keyword":["Clinching","Non-destructive testing","Computed tomography","In situ CT"],"type":"book_chapter","publication":"The Minerals, Metals & Materials Series","status":"public","abstract":[{"text":"Force–displacement measurements and micrograph analyses are commonly used methods to validate numerical models of clinching processes. However, these methods often lead to resetting of elastic deformations and crack-\r\nclosing after unloading. In contrast, the in situ computed tomography (CT) can provide three-dimensional images of the clinch point under loading conditions. In this paper, the potential of the in situ investigation of a clinching process as validation method is analyzed. For the in situ testing, a tailored test set-up featuring a beryllium cylinder for load-bearing and clinching tools made from ultra-high-strength titanium and Si3N4 are used. In the experiments, the clinching of two aluminum sheets is interrupted at specific process steps in order to perform the CT scans. It is shown that in situ CT visualizes the inner geometry of the joint at high precision and that this method is suitable to validate numerical models.","lang":"eng"}],"date_created":"2022-12-05T21:06:21Z","author":[{"full_name":"Köhler, Daniel","last_name":"Köhler","first_name":"Daniel"},{"first_name":"Robert","full_name":"Kupfer, Robert","last_name":"Kupfer"},{"first_name":"Juliane","full_name":"Troschitz, Juliane","last_name":"Troschitz"},{"last_name":"Gude","full_name":"Gude, Maik","first_name":"Maik"}],"publisher":"Springer International Publishing","date_updated":"2022-12-05T21:11:47Z","doi":"10.1007/978-3-031-06212-4_75","title":"Clinching in In Situ CT—A Novel Validation Method for Mechanical Joining Processes","publication_status":"published","publication_identifier":{"isbn":["9783031062117","9783031062124"],"issn":["2367-1181","2367-1696"]},"citation":{"mla":"Köhler, Daniel, et al. “Clinching in In Situ CT—A Novel Validation Method for Mechanical Joining Processes.” <i>The Minerals, Metals &#38; Materials Series</i>, Springer International Publishing, 2022, doi:<a href=\"https://doi.org/10.1007/978-3-031-06212-4_75\">10.1007/978-3-031-06212-4_75</a>.","short":"D. Köhler, R. Kupfer, J. Troschitz, M. Gude, in: The Minerals, Metals &#38; Materials Series, Springer International Publishing, Cham, 2022.","bibtex":"@inbook{Köhler_Kupfer_Troschitz_Gude_2022, place={Cham}, title={Clinching in In Situ CT—A Novel Validation Method for Mechanical Joining Processes}, DOI={<a href=\"https://doi.org/10.1007/978-3-031-06212-4_75\">10.1007/978-3-031-06212-4_75</a>}, booktitle={The Minerals, Metals &#38; Materials Series}, publisher={Springer International Publishing}, author={Köhler, Daniel and Kupfer, Robert and Troschitz, Juliane and Gude, Maik}, year={2022} }","apa":"Köhler, D., Kupfer, R., Troschitz, J., &#38; Gude, M. (2022). Clinching in In Situ CT—A Novel Validation Method for Mechanical Joining Processes. In <i>The Minerals, Metals &#38; Materials Series</i>. Springer International Publishing. <a href=\"https://doi.org/10.1007/978-3-031-06212-4_75\">https://doi.org/10.1007/978-3-031-06212-4_75</a>","ama":"Köhler D, Kupfer R, Troschitz J, Gude M. Clinching in In Situ CT—A Novel Validation Method for Mechanical Joining Processes. In: <i>The Minerals, Metals &#38; Materials Series</i>. Springer International Publishing; 2022. doi:<a href=\"https://doi.org/10.1007/978-3-031-06212-4_75\">10.1007/978-3-031-06212-4_75</a>","ieee":"D. Köhler, R. Kupfer, J. Troschitz, and M. Gude, “Clinching in In Situ CT—A Novel Validation Method for Mechanical Joining Processes,” in <i>The Minerals, Metals &#38; Materials Series</i>, Cham: Springer International Publishing, 2022.","chicago":"Köhler, Daniel, Robert Kupfer, Juliane Troschitz, and Maik Gude. “Clinching in In Situ CT—A Novel Validation Method for Mechanical Joining Processes.” In <i>The Minerals, Metals &#38; Materials Series</i>. Cham: Springer International Publishing, 2022. <a href=\"https://doi.org/10.1007/978-3-031-06212-4_75\">https://doi.org/10.1007/978-3-031-06212-4_75</a>."},"year":"2022","place":"Cham"}]