Micro-mechanical modeling study of the influence of cure process on the interfacial cracking of Z-pinned laminates

A novel micro-mechanical modeling approach is developed to predict the partially debonding of a Z-pin reinforced composite laminates after the cure process. Cohesive zone model (CZM) is employed to represent the interphase between Z-pin and resin. The quadratic stress criterion and the Benzeggagh-Kenane propagation criterion are coupled to determine the failure mechanism of the interphase. Numerical simulation results indicate that residual stress concentration mainly occurs in the interphase due to thermal expansion and chemical shrinkage mismatch between Z-pin and resin regions. The ultimate residual stresses could result in the interfacial cracking around the Z-pin which coincides well with the microstructural investigations. Furthermore, the influences of curing parameters on the residual stresses and cracking area are both discussed.