Coupled Fluid-Structure Analysis of Explosive Driven Fragmentation of Cylindrical Shell

The accurate numerical simulation of the dynamic response and failure of a structure to an explosive detonation product is a complex problem, involved with coupled fluid-solid description and dynamic failure of solid. This paper presents fully three-dimensional, coupled fluid-structure numerical simulations of high explosives detonated within cylindrical shell. In the analysis, the high explosive detonation and expansion are modeled using a high resolution Euler FCT solver, while the shell modeled using a Lagrangian type of solver. The Euler solver is dynamically coupled in space and time with a Lagrange solver that describes the response of cylindrical shell. In simulation of failure process, the Grady spall model, JC failure model and Gurson meso-damage model are applied to simulate the damage and fracture process of cylinders subjected to internal explosive loading. The calculations show that there are two types of failure modes in OFHC cylinders, they are spallation and shear fracture. The spall occurs at early stage, due to radial tension (parallel tension), while shear fracture happens due to shear bands and necking induced by loop tension (vertical tension) of shells after two part formation by spallation. The spall occurs only in cylinders with thick wall. In thin cylindrical shells the shear fracture predominates in expanding process, and periodicity of instability occurs. For dynamic fracture of ductile materials, application of Gurson modes gives reasonable numerical simulation of shear band nucleation, evolution and local necking fractures.