Influence of void defects on progressive tensile damage of three-dimensional braided composites

A meso-finite element model with random voids in matrix is developed to simulate the tensile progressive damage of three-dimensional braided composites. A stiffness degradation method for generating the random void defect element in finite element method is presented. Proper criteria are adopted as initial damage of components, and stiffness degradation is implemented for damage propagation. The tensile strengths are predicted from calculated stress–strain curves. From simulation, void defects in matrix make the redistribution of micro-stress and accelerate the damage propagation of three-dimensional braided composites. Furthermore, void defects reduce the strength and ductility of the composites, but the reduction is not obvious if the porosity is controlled within a range.