Determination of Johnson Cook Material Model Constants for 93% WHA and Optimization using Genetic Algorithm

An accurate material constitutive model is a key concern to develop a realistic FE models both for machining as well as penetration mechanisms. A commonly used material model in both the cases is Johnson-Cook (JC) model which is generally available in most of the commercial FE codes. The constants of the JC constitutive model are generally determined by Split Hopkinson Pressure Bar (SPHB). In this paper, experimental SHPB test data taken from literature has been utilized to determine J-C model constants under wide range of strain rates and temperatures for 93% W Tungsten Heavy alloy (WHA). The calculated values of material model constants are then optimized using Evolutionary Algorithm based technique i.e. Genetic Algorithm (GA). The predicted results would help compare the efficiency of the optimization technique used in the present work for fine-tuning the JC model constants in terms of absolute error and coefficient of correlation. Furthermore, the predicted values of JC model constants can be appropriately used for FE simulations of both machining as well as penetration mechanisms for WHA alloys. The material taken into consideration for the present study finds application typically in armour piercing ammunition. (C) 2018 Elsevier Ltd. All rights reserved.