Impact shear damage characterizations of 3D braided composite with X-ray micro-computed tomography and numerical methodologies

This paper presents the impact shear fracture mechanisms of 3D braided composite observed from computed tomography (CT) and the comparisons with finite element analyses (FEA). The effects of braiding parameters on the damage modes have been analyzed from micro-CT and FEA. It revealed that there are multiple damage modes of fiber tows fracture, debonding, resin cracks and inter-yarn delaminations under impact shear loading. The failure mode mainly depends on the braiding structural parameters, which in return determines the energy absorption capacity. A meso-structure geometrical model based on braided preform structure was developed to calculate the stress distribution and to simulate the shear damage modes. The failure modes from FEA were compared with those obtained from the micro-CT. Both the micro-CT and FEA observations capture the impact shear damage morphologies and unveil the energy absorption mechanisms.