Predicting the Johnson Cook constitutive model constants using temperature rise distribution in plane strain machining

摘要

Johnson-Cook (JC) constitutive material model is the most common, yet simplest, model to describe the material behavior in machining that involves high strain and high strain rates accompanied with high temperature rise. Many studies have tried to predict JC model constants using computational and analytical procedures. However, these approaches are limited by computational costs and experimental restrictions. In this study, an original approach to determine the JC material model constants is proposed using the effects imposed by strain hardening, strain rate hardening, and thermal softening. An analytical approach is established upon the chip formation model in orthogonal cutting—plane strain machining—where the JC model is applied to calculate cutting energy due to plasticity and friction which ultimately involves temperature rise. Temperature is calculated at primary shear zone and secondary deformation zone using Oxley and modified Hahn’s models, which are dependent on material behavior and five JC constants. JC constants are calculated by performing a multi-objective optimization algorithm that searches for the minimum differences between the calculated temperature in the chip and the experimental results of temperature for different cutting conditions. The obtained JC constants are compared with the literature and close agreements are achieved. The appeal of the proposed methodology is in its low computational time, low experimental complexity, and low mathematical complexity. Finally, JC constants were used in finite element simulation of PSM to verify the model’s robustness and accuracy via comparing the cutting force, temperature distribution, and subgrain size of the chip for different cutting conditions.