高应变速率下Al-Mg-Sc合金压缩变形的流变方程

Constitutive equation of flow for Al-Mg-Sc alloy under high strain rate

对A1-Mg—Sc材料进行静态力学性能实验，采用微型SHPB（Split Hopkinson pressurebar）实验装置对Al-Mg-Sc材料在应变率为10310。范围内进行动态力学行为测试。结果表明：Mg-Sc合金材料随应变率的提高，真实应力一应变曲线略有升高，表明Al-Mg-Sc材料不是一种对应变率敏感的材料；随着应变率的升高，材料发生的应变增大，表现出在高应变率下具有明显的应变强化效应。通过分析，选用较为合理的Johnson--Cook本构模型来构建A1．Mg．Sc合金高应变速率流变方程。根据遗传算法确定J—c方程中的参数。拟合值与实验值较吻合，证明经SHPB实验数据构建的流变方程是合理的，这为Al-Mg-Sc板料高应变速率下有限元分析需要的材料变形特性参数提供了重要的数据来源。

The static mechanics performance of the Al-Mg-Sc material was investigated, and then dynamic mechanics behavior of the Al-Mg-Sc material was measured at strain rate ranging from 1 000 to 10 000/s with the miniature split Hopkinson pressure bar （SHPB） apparatus. The results show that the Al-Mg-Sc material is not a kind of strain rate sensitive materials, but it has obvious strain strengthening effect under high strain rate. A more reasonable Johnson---Cook equation by comparing is chosen to analyze the dynamic mechanical properties of Al-Mg-Sc alloy after its relationship parameters are fitted by genetic algorithm with the experimental data. The comparison between data of experiment and fitted constitutive equation indicates that the constitutive equation is suitable for expressing the dynamic behavior of Al-Mg-Sc alloy, which provides important material characteristic parameter for mechanics numerical analysis further in the high strain rate.