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

Abstract

Metallic shaped charge jets (SCJ) have been studied for many decades across multiple communities for applications ranging from military warheads to earth penetrators for accessing oil-rich areas [1]. Researchers have had varied success in modeling these jets using simulation codes such as CTH, ALEGRA, and ALE3D. Recently, a large amount of work has been performed at the US Army Research Lab investigating the behavior of jets with increasingly sophisticated experimental diagnostics. Advances in computational resources, code enhancements, and material models have allowed us to model jets and probe uncertainties caused by algorithms, equations of state (EOS), constitutive models, and any of the available parameters each one provides. In this work we explore the effects that various EOS and constitutive models have on the development and characteristics of a 65-mm diameter, 2D copper SCJ using the Sandia National Laboratories’ multiphysics hydrocode, ALEGRA [2]. Specifically, we evaluate the tabular SESAME 3320 [3], 3325 [4-5], and 3337 [6] EOS models, analytic EOS (ANEOS) 3331 [7], as well as the Johnson-Cook (JC) [8], Zerilli-Armstrong (ZA) [9], Preston-Tonks-Wallace (PTW) [10], Steinberg-Guinan-Lund (SGL) [11-12], and Mechanical Threshold Stress (MTS) [13] constitutive models. Note that while the SGL model supports rate-dependence, there is no current characterization for copper, thus we are using rate-independent version. We do not consider the MieGrüneisen equation of state here as we expect parts of the jet to be near or cross into melt.