Tensile impact damage behaviors of co-woven-knitted composite materials with a simplified microstructure model

Abstract

The tensile damage behaviors of co-woven-knitted (CWK) composite materials under high strain rates were investigated with a simplified microstructure model. In the microstructure model, the knitted structure is homogenized with the resin in the CWK composite. Then the CWK composite was simplified as a woven structure reinforced homogenized knitted composite. In the woven composite, the mechanical properties of the resin were calculated from a homogenized, knitted-structure, reinforced composite. With this homogenization of the knitted component, the CWK composite is transformed as a woven composite. The tensile behaviors of the CWK composite under high strain rates were predicted with the finite element method (FEM) at the woven composite level. The stress–time curves and the damage fractures of the CWK composite along the warp direction (0°), the diagonal direction (45°) and the weft direction (90°) under various strain rates were obtained and compared with those from the experiments. The influences of the strain rate on the tensile behaviors of the CWK composites were analyzed both from the experiments and the FEM results. It was shown that FEM results and experimental results were in good agreement in terms of strength and failure morphology prediction. It was concluded that the simplified model and the methodology developed are suitable for the design of other kinds of hybrid-structure composite under both quasi-static and impact loading by homogenizing some parts of the reinforcing materials.