Post-multiple-Impact Damage Characterization in CFRP Laminates Using X-Ray Micro-computed Tomography
摘要
In service, barely visible impact damage (BVID) occurring in carbon fiber-reinforced polymer (CFRP) composites may not only occur in a single point, but often occurs in multiple locations. While there has been a strong interest toward multiple BVID occurring in CFRPs, research on the relationship between damage mechanisms due to multiple BVIDs and in-plane mechanical performance of CFRP is limited. This paper provides an experimental study on the multiple impact behavior of quasi-isotropic CFRP laminates and their post-multiple impact performance when subjected to tension-tension fatigue loadings. CFRP laminates were subjected to 6 J impacts at multiple locations oriented as: (1) longitudinal—in line with the loading direction, (2) transverse—perpendicular to the loading direction, (3) oblique—at 45° to the loading direction. The global response for each impact was recorded, and the interaction of damage between two impact points was evaluated using X-ray micro-computed tomography (X-CT) with advanced computational segmentation techniques. Post-impacted CFRP laminates were then subjected to fatigue loadings, and the residual modulus degradation and fatigue damage growth were investigated. Our study demonstrates that CFRP with oblique orientation multiple impacts failed earlier than the other configurations due to the interaction between impact-induced damage between impact-induced oblique cracks and edge delamination.