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: since 2017
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 372786314

Fiber-reinforced plastics (FRP) offer a high potential for lightweight designs due to their outstanding mass-specific strengths and stiffnesses. The laser as a processing tool is wear-free as a force- and contact-free thermal method, and the application of the remote process to FRP materials offers high processing speeds. As a result of the past funding period, extensive knowledge is available on the behavior of remote laser-cut FRP under static and cyclic mechanical loadings. Quasi-static tensile tests on open-hole specimens have shown that remote laser beam cutting with appropriate processing parameters leads to higher static strengths than milling. This interaction between the processing method and the material properties could be explained by a numerical model based on the finite element method, which was developed in the project. The aim of the proposed continuation project is the consequent extension of the investigations on the influence of the remote laser cutting process on the mechanical properties of FRP. In particular, the experimental and numerical proof is to be provided that the geometry of the cutting contour influences both the laser cutting process and thus the expansion of the matrix vaporization zone (MVZ), as well as the mechanical properties by the occurrence of stress concentrations. Since the MVZ itself also has a proven influence on the structural properties, complex process-structure-property relationships arise, which are to be investigated. For the consistent analysis of these relationships, the numerical process and structural models provided in the first project phase are to be extended in such a way that the damage development can be comprehensively understood and simulated. Within the scope of the continuation project, the focus is on the transfer of the previous results and findings on remote laser beam cutting of FRP to application-relevant laminates and loads. Furthermore, the assumption that aging of remote laser cut specimens leads to an increased mechanical fatigue sensitivity and a reduction of the tolerated quasi-static maximum stress is to be investigated.

• DFG Programme: Research Grants