An effective multiscale analysis for the mechanical properties of 3D braided composites considering pore defects

Pore defects are common defects in composites and can seriously affect the mechanical properties of composites. The present paper not only considers the pore defects, but also considers the influence of interface defects on the effective stiffness of 3D braided composites. A damage model is developed to predict the damage propagation of 3D braided composites considering pore defects. A multiscale simulation method using representative volume elements (RVE) combined with a micromechanical method and the finite element method is developed in this paper to meet the multiscale and periodic characteristics of 3D braided composites. The constituents at the microscale are composed of matrix, interface, fiber and pores, and the constituents at the mesoscale are composed of matrix, yarns and pores. The yarn at the microscale is homogenized by means of Mori–Tanaka model and extended double-inclusion model. The prediction and analysis methods of the existing models are compared with the experimental results to prove the effectiveness of the method.