Use of 3D simulations to investigate the effect of grooves on the surface of a plate impact experiment

Abstract
Recent studies have demonstrated that the surface finish for a plate impact specimen has little influence on the Hugoniot stress attained in it, as obtained from a uniaxial strain loading scenario [1]. However, the surface finish did clearly affect the rise time of the gauge trace due to local inhomogenieties in the wave structure. The Eulerian hydrocode GRIM3D has been used to investigate the detailed wave profiles obtained in copper to explain and quantify these effects. The simulations have been used to compare the Hugoniot stress, rise times and general wave structure in the specimen and compared with idealised an equivalent 1D loading case. An attempt is also made to identify the critical groove depth and width before the wave profile is significantly affected compared to the 1D case. This is important since some specimens are difficult to prepare to very high tolerances. The results are discussed in terms of material response, numerics and with a recommendation for further work.