Differences of transverse impact damages in 3D angle-interlock woven composites between warp and weft directions

Transverse impact damages of 3D angle-interlock woven composites have been tested at split Hopkinson pressure bar along warp and weft directions respectively. The impact deformation and damages were photographed with a high-speed camera. A finite element analyses model was established at mesostructure level to unveil the inner yarn, resin damages, and stress distributions. There are significant differences of yarn breakages and interface damage between the two directions. From finite element analysis simulations and scanning electron microscope photographs, we found the warp yarns were in kink band deformation and shear damage, while the weft yarns were in compressive failure and had smooth fractography. The warp yarns which run through-thickness directions impede transverse impact crack propagations in resins and lead to high delamination resistances. The straight weft yarns impart high stiffness and strength to in-plane directions.