A modified Zerilli-Armstrong model as the asymmetric visco-plastic part of a multi-mechanism model for cutting simulations

摘要

The Zerilli-Armstrong (ZA) model is modified to describe asymmetric visco-plastic material properties as part of a multi-mechanism model (MMM) for cutting simulations. This is done as an improvement of an existing modified Johnson-Cook (JC) model. Based on the modification of the ZA model by Samantatray et al. for elevated-temperature behaviour, we replace the hardening stress by the sum of nonlinear and linear isotropic hardening stresses using internal variables, thus consider history effects. Furthermore, weighting functions related to stress modes are applied taking asymmetric effect of strength into account. For calibrating the modified ZA model, experimental data in a wide range of strain rates and temperatures as well as under different loading types are used. Moreover, a systematic comparative study on the modified JC and ZA model is made regarding their dependence on strain, strain rate, and temperature. Finally, the modified ZA model is validated by comparing temperatures and cutting forces of cutting simulations with those of hard turning experiments.