Multi-scale structure finite element analyses of damage behaviors of multi-axial warp-knitted composite materials subjected to quasi-static and high strain rate compressions

This paper reports a multi-scale structure finite element modeling scheme to analyze the damage behaviors of biaxial multi-layer warp-knitted composite materials subjected to quasi-static and high strain rate compressions. The multi-scale structure model includes: (1) a micro/meso/macro structure model with periodic boundary conditions for homogenizing the heterogeneous fiber/resin system into unit cells, and (2) a macroscopic rate-dependent plasticity model for the knitting composite materials combined with critical damage area failure theory, which accounts for the stiffness degradation and failure strength of the material. The finite element results from the model provide the locations of stress propagation, the stress distribution, and the progressive failure behavior within the biaxial multi-layer warp-knitted composite materials. The effects of the knitted yarns and the element number sensitivity of the macro-scale model have also been discussed.