Low-velocity impact characterization of polyurethane rubber/nano-clay enriched sustainable sandwich composites: Synergy of experimentation and simulations

Abstract

This research proposes a novel sustainable composite using basalt (B), hemp (H) and polyurethane rubber (P<inf>u</inf>) reinforced in nano clay functionalised epoxy matrix for sacrificial structural applications prone to low-velocity impact (LVI). To this end, symmetric and asymmetric laminates such as HHHH, BBBB, BHHB, BHP<inf>u</inf>HB, BBP<inf>u</inf>HH and BP<inf>u</inf>BP<inf>u</inf>HP<inf>u</inf>H are fabricated using compression molding techniques and subjected to LVI at three different impact energies of 19.66, 39.39, and 59.05 J. The hemp fibers were treated with NaOH solution before fabrication. Material characterization such as X-ray diffraction, Raman spectroscopy and morphological studies has been carried out. The impact and post-impact properties of the proposed composites are experimentally evaluated and validated with the finite element (FE) results. The effect on the residual tensile strength degradation of laminates at different interlayers and energy levels is also investigated using the Caprino analytical model. The barely visible impact damages (BVID) are investigated through non-destructive dye-penetration tests, which facilitate easy identification of the prominent LVI damages like “Plateau” and “Cliff-drop” impressions. Based on the impact energy absorption and residual tensile strength, proposed laminates followed BHP<inf>u</inf>HB > BBBB > BHHB > HHHH. The experimentation suggests that Polyurethane core laminates support maximum impact energy absorption by favoring a structural change in interlayers. Also, the residual tensile strength decreases as impact velocity increases. Highlights: Low-velocity impact behavior of sustainable composites is experimented. Basalt, hemp and polyurethane rubber are reinforced in nano clay epoxy matrix. A FE framework to validate the experimentation is proposed. Dye penetrant NDT is adopted to investigate the damages. Morphological studies are conducted to understand LVI responses. © 2024 Society of Plastics Engineers.