Modeling the coupling effects of braiding structure and thermo-oxidative aging on the high-speed impact responses of 3D braided composites

We proposed a thermo-mechanical coupled model to better understand the coupling effects of thermo-oxidative aging and braiding structure on the high-speed impact responses of 3D braided carbon fiber reinforced epoxy composite. The impact responses of the aged and unaged braided composites with different braiding structures were experimentally and numerically investigated. We found that both thermo-oxidative aging and braiding structure have a significant influence on the impact responses of braided composites, and they also affect each other. Stress, adiabatic temperature rise, thermal strain and thermal stress of composites will decrease after aging, while increase with the increase of braiding angle. Increasing the braiding angle of the braided composite can effectively reduce the effect of thermo-oxidative aging on the impact responses. When the braiding angle is 42, the mechanical properties and damage of the composites are almost unaffected by thermo-oxidative aging, but the thermal stress in the impact process decreases significantly after aging.