Investigation on the tensile properties of three-dimensional full five-directional braided composites

Longitudinal tensile behaviors of three-dimensional full five-directional (3DF5D) braided composites are simulated using finite element methods (FEMs). A representative volume cell (RVC) with periodical boundary conditions is adopted to calculate the mechanical properties of the composites. In addition, the yarns are considered as uniaxial fiber-reinforced composites, and the effective mechanical properties are obtained from a RVC of yarns by using the collision algorithm. Based on the Linde failure criterion, a new damage model is proposed to describe the damage initiation and evolution in yarns, and then the longitudinal tensile strengths are predicted. Beyond this, deformation of braided preforms and pore defects are also considered in the computational model. Numerical results show that the longitudinal damage in yarns contributes to the failure of composites, and the prediction is compared with the experimental results with good agreement achieved.