---
_id: '61149'
abstract:
- lang: eng
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.
author:
- first_name: Alrik
full_name: Dargel, Alrik
id: '114764'
last_name: Dargel
- first_name: Benjamin
full_name: Gröger, Benjamin
last_name: Gröger
- first_name: Malte Christian
full_name: Schlichter, Malte Christian
id: '61977'
last_name: Schlichter
- first_name: Johannes
full_name: Gerritzen, Johannes
id: '105344'
last_name: Gerritzen
orcid: 0000-0002-0169-8602
- first_name: Daniel
full_name: Köhler, Daniel
id: '83408'
last_name: Köhler
- first_name: Gerson
full_name: Meschut, Gerson
id: '32056'
last_name: Meschut
orcid: 0000-0002-2763-1246
- first_name: Maik
full_name: Gude, Maik
last_name: Gude
- first_name: Robert
full_name: Kupfer, Robert
last_name: Kupfer
citation:
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. Proceedings of the 8th International Conference
on Integrity-Reliability-Failure (IRF2025). FEUP; 2025. doi:10.24840/978-972-752-323-8'
apa: 'Dargel, A., Gröger, B., Schlichter, M. C., Gerritzen, J., Köhler, D., Meschut,
G., Gude, M., & Kupfer, R. (2025). LOCAL DEFORMATION AND FAILURE OF COMPOSITES
DURING SELF-PIERCING RIVETING: A CT BASED MICROSTRUCTURE INVESTIGATION. In J.
F. S. Gomes & S. A. Meguid (Eds.), Proceedings of the 8th International
Conference on Integrity-Reliability-Failure (IRF2025). FEUP. https://doi.org/10.24840/978-972-752-323-8'
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={10.24840/978-972-752-323-8},
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} }'
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 Proceedings of the 8th International Conference on Integrity-Reliability-Failure
(IRF2025), edited by J.F. Silva Gomes and Shaker A. Meguid. Porto: FEUP, 2025.
https://doi.org/10.24840/978-972-752-323-8.'
ieee: 'A. Dargel et al., “LOCAL DEFORMATION AND FAILURE OF COMPOSITES DURING
SELF-PIERCING RIVETING: A CT BASED MICROSTRUCTURE INVESTIGATION,” in Proceedings
of the 8th International Conference on Integrity-Reliability-Failure (IRF2025),
Porto, 2025, doi: 10.24840/978-972-752-323-8.'
mla: 'Dargel, Alrik, et al. “LOCAL DEFORMATION AND FAILURE OF COMPOSITES DURING
SELF-PIERCING RIVETING: A CT BASED MICROSTRUCTURE INVESTIGATION.” Proceedings
of the 8th International Conference on Integrity-Reliability-Failure (IRF2025),
edited by J.F. Silva Gomes and Shaker A. Meguid, FEUP, 2025, doi:10.24840/978-972-752-323-8.'
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.'
conference:
end_date: 2025-07-18
location: Porto
name: 8th International Conference on Integrity-Reliability-Failure (IRF2025)
start_date: 2025-07-15
date_created: 2025-09-08T11:52:45Z
date_updated: 2026-02-27T06:45:17Z
doi: 10.24840/978-972-752-323-8
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
keyword:
- self-piercing riveting
- computed tomography
- thermoplastic composites
- process-structure-interaction
language:
- iso: eng
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
oa: '1'
place: Porto
project:
- _id: '133'
name: TRR 285 - Project Area C
- _id: '148'
name: TRR 285 - Subproject C04
- _id: '130'
name: 'TRR 285: Methodenentwicklung zur mechanischen Fügbarkeit in wandlungsfähigen
Prozessketten'
- _id: '131'
name: TRR 285 - Project Area A
- _id: '137'
name: TRR 285 - Subproject A03
- _id: '135'
name: TRR 285 - Subproject A01
publication: Proceedings of the 8th International Conference on Integrity-Reliability-Failure
(IRF2025)
publication_identifier:
isbn:
- '9789727523238'
publication_status: published
publisher: FEUP
status: public
title: 'LOCAL DEFORMATION AND FAILURE OF COMPOSITES DURING SELF-PIERCING RIVETING:
A CT BASED MICROSTRUCTURE INVESTIGATION'
type: conference
user_id: '105344'
year: '2025'
...
---
_id: '62078'
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. '
author:
- first_name: Johannes
full_name: Gerritzen, Johannes
id: '105344'
last_name: Gerritzen
orcid: 0000-0002-0169-8602
- first_name: Andreas
full_name: Hornig, Andreas
last_name: Hornig
- first_name: Peter
full_name: Winkler, Peter
last_name: Winkler
- first_name: Maik
full_name: Gude, Maik
last_name: Gude
citation:
ama: 'Gerritzen J, Hornig A, Winkler P, Gude M. Direct parameter identification
for highly nonlinear strain rate dependent constitutive models using machine learning.
In: ECCM21 - Proceedings of the 21st European Conference on Composite Materials.
Vol 3. European Society for Composite Materials (ESCM); 2024:1252–1259. doi:10.60691/yj56-np80'
apa: Gerritzen, J., Hornig, A., Winkler, P., & Gude, M. (2024). Direct parameter
identification for highly nonlinear strain rate dependent constitutive models
using machine learning. ECCM21 - Proceedings of the 21st European Conference
on Composite Materials, 3, 1252–1259. https://doi.org/10.60691/yj56-np80
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={10.60691/yj56-np80},
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} }'
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 ECCM21 - Proceedings of the 21st European
Conference on Composite Materials, 3:1252–1259. European Society for Composite
Materials (ESCM), 2024. https://doi.org/10.60691/yj56-np80.
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 ECCM21 - Proceedings of the 21st European Conference on Composite Materials,
2024, vol. 3, pp. 1252–1259, doi: 10.60691/yj56-np80.'
mla: Gerritzen, Johannes, et al. “Direct Parameter Identification for Highly Nonlinear
Strain Rate Dependent Constitutive Models Using Machine Learning.” ECCM21 -
Proceedings of the 21st European Conference on Composite Materials, vol. 3,
European Society for Composite Materials (ESCM), 2024, pp. 1252–1259, doi:10.60691/yj56-np80.
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.'
date_created: 2025-11-04T12:47:06Z
date_updated: 2026-02-27T06:46:21Z
doi: 10.60691/yj56-np80
intvolume: ' 3'
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
language:
- iso: eng
page: 1252–1259
project:
- _id: '130'
name: 'TRR 285: Methodenentwicklung zur mechanischen Fügbarkeit in wandlungsfähigen
Prozessketten'
- _id: '137'
name: TRR 285 - Subproject A03
- _id: '131'
name: TRR 285 - Project Area A
publication: ECCM21 - Proceedings of the 21st European Conference on Composite Materials
publication_identifier:
isbn:
- 978-2-912985-01-9
publisher: European Society for Composite Materials (ESCM)
status: public
title: Direct parameter identification for highly nonlinear strain rate dependent
constitutive models using machine learning
type: conference
user_id: '105344'
volume: 3
year: '2024'
...
---
_id: '34212'
abstract:
- lang: eng
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."
author:
- first_name: Daniel
full_name: Köhler, Daniel
last_name: Köhler
- first_name: Robert
full_name: Kupfer, Robert
last_name: Kupfer
- first_name: Juliane
full_name: Troschitz, Juliane
last_name: Troschitz
- first_name: Maik
full_name: Gude, Maik
last_name: Gude
citation:
ama: 'Köhler D, Kupfer R, Troschitz J, Gude M. Clinching in In Situ CT—A Novel Validation
Method for Mechanical Joining Processes. In: The Minerals, Metals & Materials
Series. Springer International Publishing; 2022. doi:10.1007/978-3-031-06212-4_75'
apa: Köhler, D., Kupfer, R., Troschitz, J., & Gude, M. (2022). Clinching in
In Situ CT—A Novel Validation Method for Mechanical Joining Processes. In The
Minerals, Metals & Materials Series. Springer International Publishing.
https://doi.org/10.1007/978-3-031-06212-4_75
bibtex: '@inbook{Köhler_Kupfer_Troschitz_Gude_2022, place={Cham}, title={Clinching
in In Situ CT—A Novel Validation Method for Mechanical Joining Processes}, DOI={10.1007/978-3-031-06212-4_75},
booktitle={The Minerals, Metals & Materials Series}, publisher={Springer International
Publishing}, author={Köhler, Daniel and Kupfer, Robert and Troschitz, Juliane
and Gude, Maik}, year={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
The Minerals, Metals & Materials Series. Cham: Springer International
Publishing, 2022. https://doi.org/10.1007/978-3-031-06212-4_75.'
ieee: 'D. Köhler, R. Kupfer, J. Troschitz, and M. Gude, “Clinching in In Situ CT—A
Novel Validation Method for Mechanical Joining Processes,” in The Minerals,
Metals & Materials Series, Cham: Springer International Publishing, 2022.'
mla: Köhler, Daniel, et al. “Clinching in In Situ CT—A Novel Validation Method for
Mechanical Joining Processes.” The Minerals, Metals & Materials Series,
Springer International Publishing, 2022, doi:10.1007/978-3-031-06212-4_75.
short: 'D. Köhler, R. Kupfer, J. Troschitz, M. Gude, in: The Minerals, Metals &
Materials Series, Springer International Publishing, Cham, 2022.'
date_created: 2022-12-05T21:06:21Z
date_updated: 2022-12-05T21:11:47Z
doi: 10.1007/978-3-031-06212-4_75
keyword:
- Clinching
- Non-destructive testing
- Computed tomography
- In situ CT
language:
- iso: eng
place: Cham
project:
- _id: '130'
grant_number: '418701707'
name: 'TRR 285: TRR 285'
- _id: '133'
name: 'TRR 285 - C: TRR 285 - Project Area C'
- _id: '148'
name: 'TRR 285 – C04: TRR 285 - Subproject C04'
publication: The Minerals, Metals & Materials Series
publication_identifier:
isbn:
- '9783031062117'
- '9783031062124'
issn:
- 2367-1181
- 2367-1696
publication_status: published
publisher: Springer International Publishing
status: public
title: Clinching in In Situ CT—A Novel Validation Method for Mechanical Joining Processes
type: book_chapter
user_id: '7850'
year: '2022'
...