Effect of underwater explosion on submerged bodies

Composite materials find wide use in underwater vehicles because of high strength to weight ratio and low magnetic signatures. The structural failure under explosion loading is one of the prime criteria for designing the pressure hull. The response of structures to the resultant shock loading from explosion is quite complex involving fluid-structure interaction, high strain rates, material and geometric non-linearities. Under impact loading such as shock loads, the composite hull can be subjected to fibre tension, fibre compression, matrix tension, matrix compression and matrix shear. In this paper, an attempt has been made to establish various sequence of failures associated with composite hull and the corresponding shock factors. The analysis of the submersible hull has been carried out using LSDYNA finite element code considering composite material model. The explosive and fluid domains are modelled using Eulerian solid element and the composite hull and the stiffeners using Lagrangian shell element. The explosive and the fluid domain are represented by JWL and Gruneisen equation of state respectively. The complex fluid-structure interaction problem has been solved using Arbitrary Lagrangian Eulerian (ALE) coupling.