All Eulerian method of computing elastic response of explosively pressurised metal tube

Abstract

We present an all Eulerian approach to simulate the elastic response of a metal tube loaded explosively by a gaseous detonation. The high strain rate deformation of the metal tube subjected to high explosive detonation is mathematically described by hyperbolic processes where the characteristics of existing wave motions were correlated with the local particle velocities through the speed of sound in the metal. This is a favourable case for the hydrocode which is based on a compressible gas dynamics solver and for simulating a high strain rate and dominantly plastic response of a material subject to an explosive loading. The hydrocodes fall substantially short of predicting elastic motion without the plastic flow of the confining material, for relatively minor pressure loadings due to a gaseous explosion as opposed to a high explosive detonation of a charged tube. The corresponding loading pressure due to gaseous explosion is a few orders of magnitude lower than those resulting from high explosive loadings. Utilising a hydrocode designed to handle the reactive process leading to a plastic flow of the confining materials is of great interest and a significant challenge. The new technique, based on the Eulerian framework, preserves the feature of a Lagrangian code while utilising all the benefits of an Eulerian solver that uses fixed grids with the level-sets for defining the multi-material interfaces. The hybrid particle level-set algorithm is combined with a hydrodynamic solver that adds an elasticity correction when handling the structural response while the overall scheme remained hyperbolic during the entire reactive flow. Several unseen dynamics of detonation flow associated with the elastically loaded tube of finite thickness are reported by using the present method for analysing the highly pressurised vessel.