Fracture analysis of chopped carbon fiber sheet molding compound composite under tensile loading via in-situ μXCT

This paper investigated the crack initiation in a chopped carbon fiber sheet molding compound (SMC) composite under different tensile loads by integrating synchrotron micro-X-ray computed tomography (μXCT) and micromechanics analysis. It was found that the varied distribution of fiber chips in the SMC composite led to distinct fracture propagation behaviors. With the loading increasing, the crack primarily occurred within the fiber chips, and the delamination exited when the crack propagated along the interface between adjacent layers. To understand the location and sequence of crack initiation in SMC composites, the sample were divided into identical cubes. After tracking the microstructure of each cube, the corresponding interfacial debonding strength as well as Young's modulus were predicted. Predictive modeling of crack initiation characteristics was conducted assuming homogeneous material deformation under small strain. The predicted outcomes closely matched with the experimental findings.