Evaluation of impact damage mechanism of multi-axial stitched CFRP laminate

This study focuses on multi-axial stitched fabric, which is a thick, high performance reinforcement for large-scale composite structures. The effects of impact damage on multi-axial stitched CFRP laminates molded by vacuum-assisted resin transfer molding (VARTM) method were evaluated. Impact damage within material was evaluated by ultrasonic scanning device and optical cross-sectional observations. Probed images obtained by both non-destructive and destructive methods were compared, and internal damage distributions of multi-axial stitched CFRP laminates were clarified. In addition, residual compressive strength and fatigue property of impact-damaged CFRP laminates were evaluated by in situ damage growth monitoring using the thermo-elastic stress analyzer (TESA). Three-dimensional damage distribution of impacted CFRP laminate was obtained from ultrasonic C-scan images and cross-sectional photographs. Damage progress behavior was observed on a destructive and non-destructive basis by post-impact fatigue (PIF) test.