TC4-DT钛合金材料动态力学性能及其本构模型

摘要

利用同步组装的高温分离式Hopkinson压杆试验装置,对TC4-DT钛合金材料分别进行了常温下不同应变率(930~9700 s-1)和应变率为5000 s-1时不同温度下(20~800℃)的动态力学性能测试,获得了各种冲击载荷下的应力应变曲线.试验数据表明,TC4-DT材料具有应变率增塑效应且存在着临界应变率值,当应变率高于此值时应变率敏感性增强明显,此外随着材料加热温度的升高,软化效应减弱.利用试验所得的数据拟合了基于Power-Law和Johnson-Cook两种热黏塑性本构方程且获得这两种动态本构模型参数,并将所得的两种拟合曲线与试验所得数据进行对比分析,结果表明两曲线吻合度都较好,此外还对这两种曲线的拟合精度进行对比,对比结果表明两种模型的拟合误差相差不大,但是Power-Law模型拟合精度要略优于Johnson-Cook模型的拟合精度.%The dynamic mechanics behavior experiments of TC4-DT titanium alloy materials were carried out using high temperature Hopkinson bar with synchro assembly system SHPB apparatus un-der different strain rates (930~9700 s-1 )and at room temperature and under different temperature (20~800℃)at high strain rate(5000 s-1 )respectively.The stress strain curves of TC4-DT titanium materials were obtained at high temperatures and high strain rates.The TC4-DT materials have the strain rate plasticity effect and have the critical strain rate value,above this value,the strain rate sen-sitivity increases obviously.The softening effect is weakened with the increase of heating temperature of the materials.The experimental data were fitted Power-Law and Johnson-Cook two kinds of thermal visco plastic constitutive equation respectively;and the two kinds of dynamic constitutive model parameters were obtained.the two kinds of fitting curves and the experimental data obtained were compared and analyzed.The results show that the two model predictions have a good agreement with the experimental data.Futher,the fitting precision of the two curves were compared and results show that the fitting errors of the two models are not very different,but the precision of the Power-Law model is slightly better than that of Johnson-Cook model.