High velocity impact test of a hybrid sandwich composite shield with unrestrained boundary fabric

This paper proposed a new hybrid composite shielding system aimed at increasing the specific energy absorbing rate. The hybrid composite shield is composed of an initial bumper, an intermediate layer, and a rear plate. Fabric, employed as an intermediate layer, is inserted between the front bumper and the rear back plate with an unrestrained boundary condition with minimum space. The main energy absorbing mechanism of the new hybrid composite shield is fabric pull-out through the penetration hole at the rear plate. Various types of hybrid composite shielding systems with five different kinds of rear wall were fabricated and tested to verify the realization of the fabric pull-out mechanism. High velocity impact tests were performed for each hybrid composite shield design by using a 2-stage light gas gun that can accelerate an aluminum ball of a diameter of 5.56 mm to 1 km/s. The fabric pull-out mechanism was realized when the rear wall was made of a weak plate such as PMMA, PA, or PE. Furthermore, the energy absorbing rate of the hybrid composite shield was much higher when the fabric pull-out mechanism was realized. (C) 2016 Elsevier Ltd. All rights reserved.