Nano-structured sandwich composites response to low-velocity impact

This paper investigates the influence of exfoliated nano-structures on sandwich composites under impact loadings. A set of sandwich composites plates made of fiberglass/nano-modified epoxy face sheets and polystyrene foams was prepared. The core was 25 torn thick and the face sheets were made of eight layers of woven fabric glass fibers and nano-modified epoxy (approximate to 0.8 mm of thickness). The epoxy system was bisphenol A resin and an amine hardener. The fiber volume fraction used was around 65%, while the nanoclay content varied from 0 wt.% to 10 wt.%. The nanoclay used was Cloisite 30B from Southern Clay. The sandwich panels were submitted to low-velocity impact tests with energies from 5 J to 75 J. Two sets of experiments were performed, i.e. high velocity + low mass and low velocity + high mass. Damage caused by the two groups of experiments and peak forces measured were dissimilar. The results show that the addition of 5 wt.% of nanoclay lead to a more efficient energy absorption. The failure modes were also analyzed, and they seems to be affected by the nanoclay addition to face sheets. (C) 2009 Elsevier Ltd. All rights reserved.