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

摘要

Phenomenological plastic flow stress models are used extensively in thesimulation of large deformations of metals at high strain-rates and hightemperatures. Several such models exist and it is difficult to determine theapplicability of any single model to the particular problem at hand. Ideally,the models are based on the underlying (subgrid) physics and therefore do notneed to be recalibrated for every regime of application. In this work wecompare the Johnson-Cook, Steinberg-Cochran-Guinan-Lund, Zerilli-Armstrong,Mechanical Threshold Stress, and Preston-Tonks-Wallace plasticity models. Weuse OFHC copper as the comparison material because it is well characterized.First, we determine parameters for the specific heat model, the equation ofstate, shear modulus models, and melt temperature models. These models areevaluated and their range of applicability is identified. We then compare theflow stresses predicted by the five flow stress models with experimental datafor annealed OFHC copper and quantify modeling errors. Next, Taylor impacttests are simulated, comparison metrics are identified, and the flow stressmodels are evaluated on the basis of these metrics. The material point methodis used for these computations. We observe that the all the models are quiteaccurate at low temperatures and any of these models could be used insimulations. However, at high temperatures and under high-strain-rateconditions, their accuracy can vary significantly.