Energy-absorption performance of porous materials in sandwich composites under hypervelocity impact loading

摘要

This study presents the results of an experimental investigation concerning composite structure models for hypervelocity impact-resistant composites. Sandwich models were investigated for their abilities to prevent perforation subjected to 1-7 km/s projectile hypervelocity impact loading. The models involve several material systems, dual-wall configurations, fabric-reinforced silicon carbide ceramic-matrix composite as impact-facing sheet, hollow sphere energy-absorption materials, carbon fabric and Kevlar fabric reinforced epoxy matrix composites as pressure walls. Hypervelocity impact energy decline patterns are related to impact velocity, impact-facing sheet materials, the initial porosity and the pore radius of porous energy-absorption materials, sandwich structure, pressure wall composite configurations and multi-wall structure. Stainless metal fiber reinforced silica carbon matrix composites showed much better performance than polymer matrix composites in absorbing energy and translating energy when they were used as impact-facing sheets under hypervelocity impact. The main mechanism is that stainless metal fiber reinforced silica carbon matrix composites could disintegrate bigger projectile in the first debris cloud into smaller particles and translate super high point-energy into lower facing-energy that was called the second debris cloud. The hollow sphere materials showed excellent performance in reducing impact energy in which the impact pressure dropped to "zero" when they were impacted and collapsed. Porous silicon carbide materials showed a greater ability to reduce impacting energy than hollow silica sphere and carbon sphere. The fabrication processes for composite specimens designed by theoretical number simulations and predictions were also studied. The results of hypervelocity impact tests reveals that different pressure wall composite configurations have different abilities to prevent the perforation. The sandwich composite models in 18 mm thickness designed and manufactured by the author were not perforated by a 5.4 mm diameter aluminum projectile impacted at 4.2―7.4 km/s.