Micro-mechanical analysis of matrix crack-induced delamination in cross-ply laminates in tension

A two-dimensional representative volume element model is developed to study the micro-mechanics of matrix crack-induced delamination in cross-ply laminates under longitudinal tensile loading. Fiber-matrix debonding and matrix cracking are investigated in the 90 degrees ply. The 0 degrees plies are modelled as homogenized, anisotropic elastic solids. A special emphasis is put on the interlaminar region where a thick resin-rich area is explicitly established, and delamination is characterized by a coupled plastic-damage model of the matrix. The process of delamination initiated from the matrix crack tips is accurately revealed by finite element analysis. The impact of different damage mechanisms on the macroscopic mechanical responses is quantitatively captured. A parametric study is done on different cross-ply laminates with various thicknesses of 90 degrees ply to study their effect on the variation of the homogenized longitudinal stiffness and transverse Poisson's responses. It is found that transverse Poisson's response is more sensitive to the damages in the laminate and that degradation of the responses in thicker laminates is severer. In addition, analysis of the influence of thermal residual stress shows that it changes the damage initiation location and evolution path, and affects the transverse Poisson's response more obviously.