曲率CFRP積層板の衝撃損傷後圧縮強度に関する実験的研究

抄録

Impact damage characteristics and compression after impact (CAI) strength of curved CFRP laminates were experimentally investigated. Various curved and flat CFRP laminates were prepared with special impact fixtures and compression loading fixtures. Impact tests with a range of energy levels were executed on the prepared laminates. Damage areas and their shapes after impact on the curved CFRP laminates were measured by an ultrasonic C-scanning machine. It was found that the CFRP curvature affected the impact delamination shapes (aspect ratio: AR). The delamination propagation direction followed the specimen curvature which was increased with increasing AR. After C-scope observations of delamination, compression strength tests were performed. CAI strength degradation was detected on several curvatures of 0.004 and 0.01. To further investigate the relation between CAI strength and delamination shapes, we calculated a shape factor (S) that was considered for a rectangular plate in the buckling equation. Using the actual delamination sizes as the plate size parameters in the rectangular plate buckling equation, S was calculated. The impact energy and curvature as functions of S showed very similar trends when correlated to their CAI strength test results. The results presented herein suggest that the CAI strength of curved specimens is closely related to their delamination sizes and shapes that are determined by the curvatures in the specimens.