Performance of sandwich composites subjected to sequential impact and air blast loading

An experimental study has been conducted to examine the effects of two different types of impact damage on the blast performance of sandwich composites. Sandwich composite specimens were subjected to impact by either a high velocity projectile or a low velocity drop weight. After impact, a secondary blast loading experiment was performed on the same specimens to evaluate the effects of the impact damage on the blast performance of the sandwich. Controlled blast loading was imparted using a shock tube apparatus while pressure data and high speed images of the dynamic event were captured. The experimental results showed impact damage from high velocity projectiles was most prominent on the exit face sheet of the sandwich specimens wherein damage to the core and impact face sheet, in the form of a hole, was minimal in comparison. Damage created by low velocity drop weights was concentrated on the impact face sheet and within the core adjacent to the impact face sheet. Low velocity impacts also generated de-bonding between the impact face sheet and core. Shear cracking in the core was the dominant effect of all blast loading. Although the specimens that had been struck by high velocity projectiles absorbed substantially more energy during impact experiments than those impacted by low velocity drop weights the damage created by low velocity impacts had the greatest detrimental effect on the blast performance of the sandwich composites. (C) 2010 Elsevier Ltd. All rights reserved.