(沈阳工业大学 材料科学与工程学院，沈阳 110870)
摘 要: 为研究轧制态AZ31镁合金在高应变率变形条件下的各向异性，沿镁合金板材的法向(ND)、45°方向和轧制方向(RD)分别进行应变速率700 s-1、1000 s-1、1300 s-1和1600 s-1的分离式霍普金森压杆(SHPB)实验。根据实验结果拟合得出不同加载方向下的Johnson-Cook本构方程。应用有限元分析专用前处理软件Hypermesh与显式动力学仿真软件LS-DYNA对SHPB实验过程进行数值模拟。实验与数值模拟结果表明：轧制态AZ31镁合金在高应变率条件下沿轧制方向加载时具有更强的变形能力且真应力-真应变曲线存在明显的屈服阶段；沿法向加载时表现出更明显的正应变速率强化效应和应变速率敏感性。数值模拟后处理所得真应变-时间曲线和真应力-真应变曲线与SHPB实验结果吻合度较高。不同加载方向下AZ31镁合金的Johnson-Cook本构方程参数均具有较高的拟合精度。
关键字: AZ31镁合金；高速变形；各向异性行为；Johnson-Cook本构方程；数值模拟
（School of Materials Science and Technology, Shenyang University of Technology, Shenyang 110870, China）
Abstract:In order to investigate the isotropic behavior of rolled AZ31 magnesium alloy sheet under high strain rate deformation, the Split Hopkinson Pressure Bar (SHPB) experiments were carried out along normal direction(ND), 45°and rolling direction(RD) at an average strain rate of 700 s-1, 1000 s-1, 1300 s-1 and 1600 s-1, respectively. Based on the experiment results of SHPB, Johnson-Cook constitutive equations of different deformation directions were established. The numerical simulation of SHPB was carried out by jointly using of preprocessing software Hypermesh and explicit dynamics simulation software LS-DYNA. Both experimental and simulation results showed that the rolled AZ31 magnesium alloy along RD has higher deformation ability and the yield stage in true stress-strain curves is more obvious than the other two directions. While ND shows obvious positive strain rate hardening effect and strain rate sensitivity. True strain-time curves and true stress-strain curves obtained by post-processing of numerical simulation are well agreement with the SHPB experimental results. Johnson-Cook constitutive equation parameters of rolled AZ31 magnesium alloy along different loading directions have high precision.
Key words: AZ31 magnesium alloy; high strain rate deformation; isotropic behavior; Johnson-Cook constitutive equation; numerical simulation
