Influence of void defects on impact properties of CFRP laminates based on multi-scale simulation method

The void defects produced in the composite material manufacturing process directly affect the basic mechanical properties of Carbon fiber reinforced polymers (CFRP), resulting in weakened impact resistance. This paper combines the advantages of the fast calculation speed of the macro-model and the more accurate micro-model, and proposes a multi-scale method that can judge fiber and matrix damage at the micro-scale. According to this multi-scale method, the representative volume element (RVE) of the unidirectional (UD) carbon fiber was studied, and the relationship between the six elastic properties of the CFRP and the void defects and fiber volume fraction was obtained. It was assumed that the void defects were of the same size and randomly distributed in the matrix, ignoring the effect of void shape. Analyze the impact resistance of CFRP laminates containing void defects, and the relationship between each characteristic parameter and the content of void defects. Exploring the impact resistance of CFRP laminates containing void defects, it is found that under rebound conditions, as the void content increases, the peak force decreases, the maximum displacement and the final energy absorption increase, but they are not linear. Under penetration conditions, the peak force and final energy absorption decrease nonlinearly with the increase void defect content. The innovation of this paper is to combine the multi-scale analysis method and the void defects, and obtain the relationship between the void content and the elastic properties of the CFRP, and apply the CFRP laminate containing the void defects to the impact condition, to explore its impact on impact performance.