Failure Mechanism Analysis of 3D Woven Composites Subjected to Impacts in Different Directions Under High Strain Rate Loading

ABSTRACT As the 3D woven composites have broad application prospects in aerospace and high‐speed train body structures, exploring their strain rate effects is fundamental to enhancing their out‐of‐plane impact resistance during service. This paper conducts experiments on the impact behavior of 3D woven composites under different strain rates in three directions and validates the established mesoscale finite element model. By comparing experimental and simulation results, it is found that the peak stress and maximum strain during impact compression show significant strain rate effects in all three directions, with the degree of influence being negatively correlated with fiber areal density. When the areal densities ratio of warp, weft, and out‐of‐plane direction is 1:2:0.675, and when the strain rate in the warp and out‐of‐plane directions increases by 122.22% and 41.67% respectively, the ultimate stress increases by 20.78% and 18.96%, and when the strain rate in the weft direction increases by 68.22%, the ultimate stress only increases by 6.33%. Damage in the warp and weft directions is initiated and propagated by tension between yarns caused by the impact, while the Z‐yarn plays a role in inhibiting this propagation process. Out‐of‐plane impact damage is induced by shear loading, exhibiting stronger impact compression resistance compared to in‐plane directions.