Characterization of Fatigue Damage Progress after High Velocity Impact in CFRP Cross-Ply Laminates

Carbon fiber-reinforced plastics (CFRP) possess excellent mechanical properties; however, out-of-plane impacts on CFRP laminates can induce delamination, transverse cracking, and other internal damage that are not detectable through visual inspection. Such damages significantly decrease the residual and fatigue strengths of the CFRP laminates. Consequently, understanding the post-impact fatigue behavior of CFRP is essential for ensuring and improving the long-term reliability of CFRP structural components subjected to repeated loading. In this study, impact tests using an N2-gas gun and subsequent tensile fatigue tests were performed on CFRP cross-ply laminates to evaluate the progression of delamination under cyclic loading. A fatigue damage extension model was developed to simulate delamination propagation, and finite element analysis was conducted on a specimen model incorporating impact-induced damage to examine the post-impact damage evolution. The study clarifies the damage development mechanisms of CFRP laminates under cyclic loading following impact.