Curved sandwich composites with layer-wise graded cores under impact loads

Sandwich composites with single type foam are very much prevalent in the applications to absorb energy under impact load. However, there is increasing awareness that graded cores in sandwich composites can significantly affect the impact performance. In this work, the perforation energy and failure modes of curved sandwich composites with layer wise graded cores are studied experimentally. Three types of foam were used for flat and curved sandwich composites with layered cores. A series of six different core layer arrangements were studied. The contact forces, displacements and corresponding perforation energies of square panels were measured and failure modes after perforation were observed. The results indicate that the perforation energies of the sandwich panels are dependent on various geometrical and material parameters. The perforation energies of the curved panels with single type foam were increased compared to similar flat panels, whereas panels with graded foam behaved differently due to the foam layer arrangements. Furthermore, it was observed that the failure modes were not similar when the panels were perforated. Contribution of present study to current literature is the use of different core layer arrangements to increase the impact performance of curved sandwich panels which are inevitable parts of various applications. (C) 2016 Elsevier Ltd. All rights reserved.