An FEM Analysis with Consideration of Random Void Defects for Predicting the Mechanical Properties of 3D Braided Composites

Abstract

Random void defects have detrimental effect on the mechanical properties of 3D braided composites. A 3D FEM based on a periodic representative unit cell is developed to appraise the mechanical properties of 3D 4-directional braided composites containing the defects. Two basic types of void defects, such as the dry patches in the reinforced yarns and the voids in the resin matrix pocket, have been taken into account. A simple method for generating the random void defect elements in FEM is presented. The FE software ABAQUS is adopted to study the elastic properties. The predicted effective elastic properties are in good agreement with the available experimental data, demonstrating the applicability of the mesomechanical FEM. By considering the random distribution of void defects, the probability statistics analysis of mechanical properties was conducted. In addition, the effect of the void volume fraction on the elastic properties was discussed in detail, and some useful conclusions were drawn herein.