Innovative meshless approach for shaped charges applications

Abstract

We focus here on modelling shaped charges. Combining large deformations, numerous interfaceproductions, and strong damage mechanisms, those events are particularly challenging from a numerical point of view. Eulerian finite element methods are classically used for such modeling.However, they induce very long computation times, accuracy losses (projection algorithms), anddifficulties with opening criteria related to jet fragmentation. Among the Lagrangian approaches, the meshless method called Smoothed Particle Hydrodynamics (SPH) appears as a relevant alternative to prevent such shortcomings. Based on a set of moving interpolation points, it disregards any connectivity between its elements which makes it naturally well suited to handle material failure. Nevertheless, SPH schemes suffer from well-known instabilities questioning their accuracy and activating nonphysical processes,such as numerical fragmentation. Many stabilizing tools are available in the literature however, they either raise conservation and consistency issues or drastically increase the computation times. We propose then to use an alternative scheme called γ-SPH-ALE. Based on the ALE framework, it achieves robust and consistent stabilization through an arbitrary description of motion. Thanks to CFL-like conditions obtained through a nonlinear stability analysis, the scheme stability is ensured. By preventing spurious oscillations in elastic waves and correcting the so-called tensile instability, both stability and accuracy are increased regarding classical approaches. Also, taking advantage of GPU computing, such results are achieved in reduced computation times contrary to classical CPUimplementations. Its implementation on a “Viper” shaped charge shows that the scheme handles the jet generation process as well as its resulting interaction with a target.