Thickness effect on repeated impact response of woven fabric composite plates

This paper presents an experimental investigation on the repeated impact response of woven E-glass/epoxy composites with various thicknesses. Energy profile diagrams of the samples, the variation of perforation thresholds with thickness and the variation of absorbed energy with repeat numbers are provided. Considering varied energy levels, the impact numbers causing complete perforation of the specimens are also depicted. Along with some images of the perforated samples for both single impact and repeated impact cases, the contour plots of the damage expansion with increasing impact numbers are also provided for better understanding. It is found that the perforation threshold/energy for single impact varies linearly with thickness for the chosen composite plates. Considering different energy levels, the impact numbers corresponding complete perforation of the specimens with different thicknesses, i.e. layer numbers, are also provided. It is found that the data points of the each thickness, using power regression, may be written as; E-i = aN(r)(b), where E-i stands for impact energy, N-r, for the "repeat number of impact to perforation", while a and b are the constants. The equations found enable to predict the number of impacts for perforation (NO under smaller impact energies, without testing. (C) 2013 Elsevier Ltd. All rights reserved.