Study of air-backed and water-backed carbon fiber composite plates subjected to underwater shock loading

Abstract

A collection of experimental and numerical studies was conducted for laminated carbon fiber composite plates of different layup orientations to investigate their response and failure when subjected to underwater shock loading. The composite plates were clamped within a rigid fixture and submerged within an anechoic water tank while having either an air-back or water-back supporting condition. Plastic bottles partially filled with liquid nitrogen were used to generate shock pressures whose characteristics were closer to that resulting from the pulsation of a gas bubble rather than the detonation of an explosive. A multiphysics model based on fluid–structure interaction was considered for the numerical study. A multiscale approach was also used for the numerical study to predict failure based on the constituent material level (i.e., fiber and matrix material level). Both experimental and numerical results agreed well, indicating that the water-backed carbon fiber plate had a very localized failure while the air-backed composite plate showed global failure. The critical stand-off distance for the failure of the water-backed carbon fiber composite was approximately half of that for the air-backed composite plate of the same layup orientation. In other words, the water-backed carbon fiber composite plate had greater damage tolerance than the air-backed plates.