Geometry and Size Effects in Response of Composite Structures Subjected to Water-Based Impulsive Loading

Abstract

The load-carrying capacity of composite structures under water-based impulsive loads is an important consideration in design. The performance is inherently geometry and size dependent. Studies of the issues must be in relation to materials, structural geometries, and loading conditions. Analyses have focused on the role of fiber orientation, fiber stiffness, and incident impulse intensity on the deformation and failure in monolithic carbon-fiber and glass-fiber/epoxy composite plates and cylinders of similar mass and thickness. In experiments, structures are subjected to impulsive loads of different intensities generated using the Underwater Shock Loading Simulator (USLS), a novel projectile-impact-based impulsive loading facility. In situ high-speed digital imaging has been used to study the deformation and failure, focusing on the effects of load intensity, failure modes, and material heterogeneity. The experiments are combined with fully dynamic 3D Coupled Eulerian–Lagrangian (CEL) finite element simulations accounting for the effects of fluid–structure interactions (FSI) and in-ply and inter-ply cracking and failure. It is found that the carbon-fiber laminates provide higher blast resistance, but transmit a greater fraction of the incident impulse to the supports than the glass-fiber laminates. Damage through in-ply and inter-ply cracking in the carbon-fiber laminates is ~25% of that in the glass-fiber laminates. In the case of cylindrical structures, results show that cylindrical sandwich structures have superior blast resistance than cylindrical monolithic structures of equal mass with only relatively minor increases in wall thickness.