Effects of equations of state and constitutive models on simulating copper shaped charge jets in ALEGRA

Abstract

We investigate the effects of copper equations of state and constitutive models on simulations of shaped charge jets using the Sandia National Laboratories’ multiphysics hydrocode, ALEGRA. Specifically, we compare (1) the 3320, 3325, 3331, and 3337 SESAME copper equations of state (EOS), and (2) Johnson–Cook, Zerilli–Armstrong, Preston–Tonks–Wallace, Steinberg–Guinan–Lund, and Mechanical Threshold Stress constitutive models. Several of these cases are also compared against photon Doppler velocimetry measurements of the tip velocity. Lagrangian tracer particles are used to follow a part of the jet's evolution in state space for the various models. We monitored the jet topology and found that the various EOS produce similar results, although the 3325 model generates a cavity near the jet tip whose size decreases with increasing mesh resolution. Constitutive models generated more noticeable differences. We found the SGL and PTW models produced higher temperatures while the MTS and JC models returned very similar results at lower temperatures. The SGL model was the only strength model that reported a liquid region along the axis of the jet. For all material models, we found similar results for the velocity history of the jet tip as measured against experiment using photon Doppler velocimetry.