Advancements in modelling aluminium alloy AA2195 behaviour: a comprehensive study of the Johnson Cook model

The Johnson-Cook (JC) constitutive model of the aluminium Alloy AA2195 was calibrated for a wide range of strain rates (0.0001-10,100 s-1) and temperatures (420-520°C) in this study. True stress-strain curves were determined from tensile tests and yield stress was calculated using the 0.2% offset method, before a process of non-linear least squares fitting was performed via a Python script and constrained optimisation. A successive approach was applied to reduce the impact of various parameters. The optimised JC parameters were determined as A = 429.11 MPa, B = 123.01 MPa, n = 0.6466, C = 0.0486, and m = 9.2885. The JC model fits to the experimental data reasonably well, with R2 (coefficient of determination) values from 0.821 to 0.994 for different thermo-mechanical loading conditions. The average absolute prediction error was 5.66 MPa, with good predictive performance. The findings show a low strain-rate sensitivity and high thermal softening contribution of AA2195. The model provides a practical approach for finite element simulation of aerospace forming and high-strain-rate impacts.