The Influence of Velocity in Low-Velocity Impact Testing of Composites Using the Drop Weight Impact Tower

Abstract

Many structural advantages offered by composites due to their inherent tailorability await realization for lack of a clear understanding of their response under transient loading. One tool currently available for evaluation of impact response is the drop weight impact tower. In this paper, we address the influence of impact velocity in drop tower testing using woven and non-woven E-glass fabric-reinforced vinyl-ester composites fabricated by resin transfer molding (RTM). For the range of impact velocities attainable in a typical drop weight impact tower (< 7 m/s), impact energy and contact force determine the extent and type of damage. Impact velocity determines the initial loading slope and time taken to reach maximum load; however, it only marginally influences inelastic damage accumulation. Peak contact force increases linearly with impact energy and projected damage area up to the linear inelastic limit (LIL), which is described as the point where top surface penetration commences. While independent of impact velocity, LIL marks the upper limit of applicability for the well-known linear relationship between projected damage area and impact energy. Beyond LIL, these two composite systems offered no increased resistance to load application, suggesting that ultimate contact force may be an important impact metric.

A comparison of quasi-static indentation and low-velocity impact on composite overwrapped pressure vessels

“…20 The linear progression of delaminated area above a threshold loading observed in this study has been described in many previous studies of both CFRP and GFRP plates, e.g. see Bull et al., 11 Cartie and Irving, 20 Rydin et al., 21 but has not been reported previously for COPVs.…”

Impact damage on fibre-reinforced polymer matrix composite – A review

“…Rydin et al 53 have investigated the influence of impact velocity on woven and non-woven composites. For the range of impact velocities attainable in a typical drop weight impact tower (<7 m/s), impact energy and contact force determine the extent and type of damage.…”

Experimental and computational study of the damage process in CFRP composite beams under low-velocity impact

“…Transverse (out-of-plane) loading of aerospace structures generally takes place at their external regions in the form of dynamic impact by foreign objects. Transverse impact of composites has long been studied in terms of understanding the damage mechanism [2][3][4], the effects of geometry [5][6][7][8] and the impact parameters [9][10][11] for improving damage resistance of structures.…”