高应变速率下SiC_(p)/Al复合材料的动态力学性能及其本构关系

Dynamic Mechanical Properties and Constitutive Relation of SiC_(p)/Al Composites under High Strain Rate

利用分离式Hopkinson压杆试验装置对体积分数15%SiC_(p)/Al复合材料进行动态压缩试验,研究了该复合材料在500~2000 s^(-1)高应变速率下的动态力学性能及其显微组织演变;基于试验数据,通过包含与应变速率和塑性应变相关的绝热温升软化项的Johnson-Cook本构模型对应力-应变曲线进行预测,并将模型预测结果与试验结果进行对比。结果表明:复合材料的应变速率强化效应不明显,但是该材料具有显著的应变强化效应;随着应变速率的增加,复合材料的变形类型由均匀变形向局部化变形转变,增强相颗粒破裂严重,绝热剪切带在局部区域形成并扩展;采用包含绝热温升软化项Johnson-Cook本构模型计算得到的应力-应变曲线与试验结果间的相对误差小于17%。

Dynamic compression tests of the 15%(volume fraction)SiC_(p)/Al composite were carried out by separate Hopkinson compression bar device,and the dynamic mechanical properties and microstructure evolution of the composite at high strain rates of 500-2000 s^(-1) were studied.With the experimental data,stress-train curves were predicted by the Johnson-Cook constitutive model containing the adiabatic temperature rise softening term relating to strain rate and plastic strain,and the predicted results of the model were compared with the experimental results.The results show that the strain rate strengthening effect of the composites was not obvious,but the composites showed a significant strain strengthening.With increasing strain rate,the deformation types of the composite changed from uniform deformation to localized deformation,the fracture of the reinforcing particles was serious,and the adiabatic shear bands were formed and extended in local areas.The relative error between the stress-strain curves calculated by the modified Johnson-Cook constitutive model containing the adiabatic temperature rise softening term and the experimental results was less than 17%.