An evaluation of plastic flow stress models for the simulation of high-temperature and high-strain-rate deformation of metals

TL;DR

This paper compares five phenomenological plastic flow stress models for simulating high-temperature, high-strain-rate deformation of metals, focusing on their accuracy and applicability to OFHC copper.

Contribution

It provides a systematic evaluation of five flow stress models against experimental data and impact tests, highlighting their strengths and limitations in different regimes.

Findings

All models are accurate at low temperatures.

Model accuracy varies significantly at high temperatures and strain rates.

OFHC copper's behavior is well characterized for model validation.

Abstract

Phenomenological plastic flow stress models are used extensively in the simulation of large deformations of metals at high strain-rates and high temperatures. Several such models exist and it is difficult to determine the applicability of any single model to the particular problem at hand. Ideally, the models are based on the underlying (subgrid) physics and therefore do not need to be recalibrated for every regime of application. In this work we compare the Johnson-Cook, Steinberg-Cochran-Guinan-Lund, Zerilli-Armstrong, Mechanical Threshold Stress, and Preston-Tonks-Wallace plasticity models. We use OFHC copper as the comparison material because it is well characterized. First, we determine parameters for the specific heat model, the equation of state, shear modulus models, and melt temperature models. These models are evaluated and their range of applicability is identified. We then compare the flow stresses predicted by the five flow stress models with experimental data for annealed OFHC copper and quantify modeling errors. Next, Taylor impact tests are simulated, comparison metrics are identified, and the flow stress models are evaluated on the basis of these metrics. The material point method is used for these computations. We observe that the all the models are quite accurate at low temperatures and any of these models could be used in simulations. However, at high temperatures and under high-strain-rate conditions, their accuracy can vary significantly.