A modified Johnson-Cook model for 7N01 aluminum alloy under dynamic condition

摘要

Tensile tests at different strain rates (0.0002, 0.002, 0.02, 1000 and 3000 s-1) were carried out for 7N01 aluminum alloy. Low strain rate experiments (0.0002, 0.002 and 0.02 s-1) were conducted using an electronic mechanical universal testing machine, while high strain rate experiments (1000, 3000 s-1) were carried out through a split Hopkinson tensile bar. The experimental results showed that 7N01 aluminum alloy is strain rate sensitive. By introducing a correction scheme of the strain rate hardening coefficient, a modified Johnson-Cook model was proposed to describe the flow behaviors of 7N01 aluminum alloy. The proposed model fitted the experimental data better than the original Johnson-Cook model in plastic flow under dynamic condition. Numerical simulations of the dynamic tensile tests were performed using ABAQUS with the modified Johnson-Cook model. Digital image correlation was used together with high-speed photography to study the mechanical characters of specimen at high strain rate. Good correlations between the experiments results, numerical predictions and DIC results are achieved. High accuracy of the modified Johnson-Cook model was validated.