Shock Modelling of Multi-Phase Materials: Advances and Challenges

This paper presents part of an ongoing programme of work on high velocity impact modelling on composite targets. The modelling approach aims to link existing low velocity constitutive failure models, including delamination modelling, with relevant orthotropic Equations Of State models. A methodology for predicting the Hugoniot states (shock velocity vs. particle velocity) of multi-phase materials at high compression is presented. The Gruneisen parameter of the mixture is also derived. The proposed approach is a step toward a full thermodynamic virtual characterisation of untested multi-phase materials, when tabulated shock data for the constituents is available [1]. Other approaches have been proposed [2], [3]; however, they require complex Finite Element coding and iterative procedures and are limited to two-phase materials. The approach is critically discussed in relation to shock data derived from existing flyer plate impact test data. An orthotropic Equation of State [4] has also been implemented into the LS-DYNA3D code. A flyer plate test is simulated using the implemented model, and with material parameters derived using the theory of mixture approach. The current orthotropic Equation of State formulation is discussed, within the limitation of classical Lagrangian FE techniques. Additionally, conclusions are drawn on the logical next step to model high velocity angled impacts onto orthotropic targets.