Analysis of the correlation between fatigue behavior of remote laser cut fiber reinforced composites and process parameters

• Applicants: Professor Dr.-Ing. Markus Kästner; Professorin Dr.-Ing. Martina Zimmermann
• Subject Area: Mechanical Properties of Metallic Materials and their Microstructural Origins ; Mechanics
• Term: from 2017 to 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 372786314

• Final Report Year: 2025

Final Report Abstract

This project encompasses a comprehensive systematic investigation of the remote laser cutting process of fiber-reinforced plastic composites, the thermally induced damage caused by this process and the effects on the mechanical properties of the cut structures. One focus was the systematic analysis of the cutting process and the influence of the various process parameters through cutting tests as well as the investigation of the heat-affected zone with micrographs, computer tomography and scanning electron microscope images. To analyze the mechanical properties, the properties of thermally undamaged samples were compared with laser-cut samples with varying damage intensity in quasi-static and cyclic tests. For this purpose, samples, provided with a central hole were used in which the maximum stress is in the area of the heat-affected zone due to the notch effect. The analyses were systematically extended by varying other parameters such as the layer structure and notch geometry, load increase tests and the investigation of chemically aged samples. It was shown that remote laser-cut samples have a higher strength compared to milled and CO2 laser-cut samples. This could be attributed to a reduced notch effect at the edge of the hole due to the limited heataffected zone. In order to numerically investigate the cutting process, the thermally induced damage and the mechanical behavior of the laser-cut samples in a closed process-structure-property chain, a physically based cutting process model, a material model for the mechanical properties of the thermally induced damaged material and a model for the fatigue of the fiber-reinforced plastic composite were developed. The use of physically based models enables rapid adaptation to new process and material configurations without the need for new experimental investigations. With the developed cutting process model, a three-dimensional model with consideration of the laser beam for direct mapping of the material removal of fiber-reinforced plastics was presented for the first time. The knowledge gained in the research project was presented to a broad public through publications and presentations at national and international conferences. The project was the first fundamental investigation of the cutting process with a special focus on the mechanical properties of the cut structures, which was made possible by the effective combination and mutual extension of experimental investigations and numerical simulations.

Publications

• Die kapazitive Wechselstrommessung zur Werkstoffcharakterisierung kohlenstofffaserverstärkter Kunststoffe. Tagung Werkstoffprüfung 2019 Werkstoffe und Bauteile auf dem Prüfstand. Sankt Augstein, Inventum GmbH, 349-354, 2019. ISBN 978-3-88355-418-1
  Rose, M.; Pschan, N.; Zimmer, O.; Nimsch, U.; Ostwaldt, A.; Träger, P. & Zimmermann, M.
  
• Influence of the edge quality to the water sorption of remote laser and mechanically cut carbon fibre reinforced polymer. 4th International MERGE Technologies Conference, IMTC 2019. - Chemnitz: MERGE, 34-41. 2019. ISSN 2512-4587
  Rose, M.; Mickan, A.; Hauptmann, J.; Wetzig, A. & Zimmermann, M.
  
• Numerical analysis of the thermally induced damage in remote laser cut carbon fibre reinforced polymers. PAMM, 19(1).
  Schmidt, Benjamin; Rose, Michael; Zimmermann, Martina & Kästner, Markus
  
• Numerical and experimental analysis of the thermally induced damage in remote laser cut carbon fiber reinforced polymers. Vortrag: CFRAC2019, Braunschweig, 2019.
  Schmidt, B., Rose, M., Zimmermann, M. & Kästner, M.
  
• Numerical and experimental analysis of the thermally induced damage in remote laser cut carbon fiber reinforced polymers. Vortrag: Mech-COMP2019, Lissabon, 2019
  Schmidt, B., Rose, M., Zimmermann, M. & Kästner, M.
  
• Prüfmethodik zum Schädigungsverlauf von Remote-Laser geschnittenen CFK unter zyklischer mechanischer Beanspruchung. Vortrag: 22. Symposium Verbundwerkstoffe und Werkstoffverbunde. Kaiserslautern, 2019
  Rose, M.; Schettler, S.; Beyer, E. & Zimmermann, M.
  
• Mechanical Properties of Remote-Laser Cut CFRP and Thermographic Laser-Process Monitoring. Materials Sciences and Applications, 11(08), 560-575.
  Rose, Michael; Schettler, Sebastian; Klemm, Florian; Beyer, Eckhard & Zimmermann, Martina
  
• Analysis of process-induced damage in remote laser cut carbon fibre reinforced polymers. Journal of Materials Processing Technology, 295, 117162.
  Schmidt, Benjamin; Rose, Michael; Zimmermann, Martina & Kästner, Markus
  
• Analysis of the remote laser cutting process induced damage in carbon fibre reinforced polymers with cutting process simulations. PAMM, 20(1).
  Schmidt, Benjamin; Rose, Michael; Zimmermann, Martina & Kästner, Markus
  
• Analysis of the remote laser cutting process induced damage in carbon fibre reinforced polymers. PAMM, 21(1).
  Schmidt, Benjamin; Husert, Markus; Rose, Michael; Zimmermann, Martina & Kästner, Markus
  
• X-ray computer tomography (XCT) of fatigue damage in laser-machined versus milled carbon fiber reinforced polymer matrix composites. Engineering Fracture Mechanics, 252, 107820.
  Rose, Michael; Niverty, Sridhar; Schmidt, Benjamin; Kästner, Markus; Zimmermann, Martina & Chawla, Nikhilesh
  
• Analysis of the remote laser cutting process of carbon fibre reinforced polymers and its influence on mechanical properties, Vortrag ECCM20, Lausanne, 2022
  Schmidt, B.; Zimmermann, M. & Kästner, M.
  
• Analysis of the remote laser cutting process of carbon fibre reinforced polymers and its influence on mechanical properties, Vortrag GAMM2022, Aachen, 2022
  Schmidt, B.; Zimmermann, M. & Kästner, M.
  
• Analysis of the remote laser cutting process induced damage in carbon fibre reinforced polymers. PAMM, 23(1).
  Schmidt, Benjamin; Husert, Markus; Hollmer, Katharina; Zimmermann, Martina & Kästner, Markus
  
• Numerical investigation of the process-structure-property relationship of remote laser cut CFRP structures, Vortrag GAMM2023, Dresden, 2023
  Schmidt, B.; Hollmer, K.; Zimmermann, M. & Kästner, M.
  
• Untersuchung des Einflusses der Kerbgeometrie auf das quasistatische und zyklische mechanische Verhalten remote-lasergeschnittener kohlenstofffaserverstärkter Kunststoffe. Tagung Werkstoffprüfung 2023: Werkstoffe und Bauteile auf dem Prüfstand. 216-221
  Hollmer, K.; Schmidt, B.; Kästner, M. & Zimmermann, M.
  
• Analyse und Modellierung des Remote Laser-Schneidprozesses von Strukturen aus kohlenstofffaserverstärkten Kunststoffen. Dissertation, Dresden
  Schmidt, B.
  
• Einfluss des Remote-Laserschneidprozesses auf das mechanische Verhalten kohlenstofffaserverstärkter Kunststoffe in Abhängigkeit der Kerbgeometrie und Schneidparameter. Vortrag: 24. Symposium Verbundwerkstoffe und Werkstoffverbunde. Freiburg 2024
  Hollmer, K.; Schmidt, B.; Kästner, M. & Zimmermann, M.