BLAST PERFORMANCE OF COMPOSITE SANDWICH STRUCTURES

Sandwich composite materials possess low radar signatures, high strength-to-weight ratios and tailorable mechanical properties, but their blast resistance is not well understood. This paper presents the results of full scale air blast tests performed on a graded density foam core sandwich panel, to determine if the use of a graded core can be used to mitigate blast damage. The results are obtained using high speed 3D digital image correlation, and post-blast damage assessment. It was found that back face-sheet damage could be prevented by using a graded sandwich panel as there is less cracking towards the back of the panel, and the epoxy between the foam layers impedes crack propagation through the foam, resulting in less overall damage. The second part of this paper presents findings from a study performed using the UNDEX simulation tool in Abaqus to model the fluid-structure-interaction in underwater blast scenarios. These results were verified with full scale underwater blast testing performed in Norway in 1988 in connection with the development of a series of mine countermeasure vessels for the Royal Norwegian Navy. Using this method it was possible to successfully model cavitation development and closure in front of the tested sandwich structure, and strong agreement was found from electrical strain gauges placed on the front face-sheet of the sandwich panels in the underwater blast test experiments.