Micromechanisms and Characterization of Low-Velocity Impact Damage in 3D Woven Composites

Abstract

Low-velocity impact (LVI) damage of 3D woven composites were experimentally and numerically investigated, considering different off-axis angles and impact energies. The impact responses were examined by LVI tests, and the damage morphology inside the composites was observed by X-ray micro-computed tomography (μ-CT). Yarn-level damage evolution was revealed by developing a hybrid finite element analysis model. The results show that the impact damage has significant directionality determined by the weft/warp orientation of the composites. The damage originates at the bottom of the impacted area and then expands outwards and upwards simultaneously, accompanied by in-plane and out-of-plane stress transfers. The straight-line distributed weft/warp yarns play an important role in bearing loads at the beginning of loading, while the w-shape distributed binder warp yarns gradually absorb impact deformation and toughen the whole structure as the loading proceeds. The effect of directional impact damage on post-impact performance was explored by performing compressing-after-impact (CAI) tests. It is revealed that the CAI properties along principal directions are more sensitive to the low-velocity impact, and the damage mode is significantly affected by the loading direction.

Numerical Study of the Influence of the Structural Parameters on the Stress Dissipation of 3D Orthogonal Woven Composites under Low-Velocity Impact

“…Another crucial factor that influences the mechanical and impact performance of 3DOW composites is the x-yarn density. Sun's utilization of micro-CT for evaluating lowvelocity damage in 3D composites revealed that the directionality of impact damage was predominantly governed by the weft/warp orientation [26]. Subsequent finite element analyses accentuated the critical role of x-and y-yarns in energy absorption at the impact's onset.…”

Low-Velocity Impact and Post-Impact Residual Flexural Properties of Kevlar/EP Three-Dimensional Angle-Interlock Composites

“…Traditionally, the CAI has been widely used to evaluate the postimpact performance of composites. Extensive experimental and finite element studies have been conducted, with the research literature primarily focusing on the impact damage mechanisms of composite laminates, the relationship between the residual strength and impact damage, and the influence of the fabric structural parameters on the residual mechanical properties [19][20][21]. However, there is relatively little research on the TAI and FAI [22].…”