Effect of rate-dependent constitutive equations on the tensile flow behaviour of DP600 using Rousselier damage model

Abstract

In the current research, the Rousselier ductile damage model was employed to model hardening, plastic instability and damage properties of DP600 during uniaxial tension in a wide range of strain rates (from 0.001 to 1000s−1). Also, various well-known phenomenological hardening functions, such as Johnson–Cook and KHL as well as a modified version of Johnson-Cook and multiplicative combinations of Voce with other strain-rate hardening functions have been fitted to experimental flow curves via a new combination of non-linear regression and Markov chain Monte Carlo (MCMC) method. The effect of each hardening function on the evolution of the damage parameter, void volume fraction and strain distribution along the gauge length was evaluated throughout the deformation. Also, the onset of instability, geometry of the neck and final fracture were then assessed by comparing the numerical results with experimental data. It is found that the modified JC and Voce-modified JC models can predict the flow behaviour of DP600 more accurately. Additionally, it is shown that the strain hardening rate at large strain levels, as determined by the hardening models, has a considerable effect on the strain map along the specimen, onset of void growth, and progression of damage in the localized area.