LAUSR

Three-dimensional (3D) woven composites have been widely used in structural components due to their excellent mechanical and near-net-shape properties. However, for some special applications, it is expected that 3D woven composites can be damaged at designated locations under a specific load. In this research work, a new kind of defect-prefabricated 3D woven composites (DP3DWCs) are designed, where defects are prefabricated by cutting weft or warp yarns in defect-free 3D woven composites (DF3DWCs). The tensile mechanical properties of the DF3DWCs and the DP3DWCs are investigated experimentally and numerically. The mesoscopic geometry models of the DF3DWCs and the DP3DWCs were established by multi-objective searching algorithm. The progressive damage models were established using the 3D Hashin criteria and the von Mises failure criterion. Numerical results agree well with the experimental data. The influence of the number of defect layers on the mechanical properties was also discussed. The obtained results indicate that the defects have little effect on the elastic modulus, while tensile strengths decrease linearly with the increase of the number of defect layers. Failure mechanisms of yarns and matrix in the non-defective and defective materials were studied, and the volume fraction of elements of each failure mode was computed and analysed.