A modified Johnson-Cook model of AA6061-O aluminum alloy with quasi-static pre-strain at high strain rates

Abstract

In this paper, specimens were first pre-stretched to different pre-strain coefficients (0, 0.4 and 0.8) under quasi-static tensile for AA6061-O aluminum alloy. Then, the specimens with different pre-strain coefficients were stretched by a high-speed tensile machine (HTM) at different strain rates (200 s− 1, 400 s− 1 and 600 s− 1). Digital image correlation (DIC) technique was employed to measure the strains. The results showed that the yield ratio increased significantly with the pre-strain increased. As the pre-strain coefficient increased, high-speed tensile strain limitation decreased and the total tensile strain limitation increased. A modified Johnson-Cook (JC) model considering pre-strain coefficient was proposed. Numerical simulations were performed using LS-DYNA with the modified JC model. The strain field of the specimen taken by the camera agreed well with the simulated strain field.