A modified Johnson-Cook model for tensile flow behaviors of 7050-T7451 aluminum alloy at high strain rates

The uniaxial quasi-static and dynamic tensile tests were conducted at different strain rates (10^-3s^-1, 800s^-1, 1900s^-1 and 2900s^-1) for 7050-T7451 aluminum alloy. Then, research of the strain rate hardening coefficient in the original Johnson-Cook model at different strains and strain rates showed that the coefficient is a function of strain and strain rate from the tensile experimental results. Furthermore, a modified Johnson-Cook model was proposed to describe the flow behaviors of the studied alloy based on the correction to the strain rate hardening coefficient. Comparisons between the experimental data and predicted results using the original JC model, Khan-Liu (KL) model and the modified JC model showed that a better agreement can be obtained applying the modified model than the other two models. Verifications for predicting three new high strain rates (1500s^-1, 2500s^-1 and 3500s^-1) experimental data demonstrated the modified JC model can provide an accurate description for the dynamic behaviors of the studied alloy.