Blast response of sandwich structures: The influence of curvature

This chapter presents results from a study on the response of singly curved fibre-reinforced polymer (FRP) sandwich panels subjected to close-proximity blast loading, with the panel oriented so that the convex side was facing the blast. The influence of radius of curvature was explored by manufacturing and testing panels with three external radii of curvature (infinite (flat), 1000, and 500 mm). The loading was generated by detonating 10–30-g circular discs of PE4 plastic explosive at a constant standoff distance of 100 mm. Multiple failure modes were identified by a posttest inspection of the panels. Failure modes of the face sheets included delamination, matrix failure, and fibre fracture. Core compression, core shear, and fragmentation were observed in the core material. Failure of the FRP sandwich panels was initially more prevalent on the front face sheet and in the core material. Increasing the charge mass resulted in the rupture of the front face sheet and penetration of the core, which caused higher load transfer to the back face sheet. Lower impulses were transferred to the convexly curved panels when compared to flat panels subjected to the same charge mass detonations, although there was no discernible difference between the impulses transferred to the 1000- and 500-mm radius panels. The curved panels were also able to withstand higher charge masses than the flat panels without exhibiting rupture. Failure (particularly delamination) was more prominent along the axis of curvature at low charge masses, but at higher charge masses, the failures were more prominent perpendicular to the axis of curvature, particularly rupture and cracking of the face sheets.