The numerical and experimental investigation on low-velocity impact response of composite panels: Effect of fabric architecture

The aim of this study is to characterize and assess the effect of fabric structure on the damage resistance subjected to low velocity impact. Composite panels reinforced by layered unidirectional (LU), layered woven (LW) and 3D orthogonal woven (OW) fabric were prepared respectively and the impact tests were carried out on a low-velocity testbench. Finite element models at yarn-level were established to numerically investigate the material deformation and failure mechanism. The impact tests showed that the OW composite possessed better impact resistance with respect to impact-induced deformation and inelastic energy absorption. The roles of the z-binder have also been identified through comparison of impacted morphology and numerical results. The z-binder serves as cracking trigger due to the weak debonding with resin pocket around it and its zig-zag configuration impedes the growth of delamination by damage deflection. Therefore, the discontinuous resin damage in 3D composite allows the enhancement of impact resistance instead of delamination failure in the 2D panel. In addition, the in-plane interlacement of woven fabric causes that primary yarn breaks in the high stress region and forms a circle damage area, whereas the penetrating cracking along the fiber orientation of superficial layer is induced in the unidirectional composite.