TC4钛合金力学性能测试及其本构关系研究

Mechanical properties and constitutive relationship of TC4 titanium alloy

为合理描述TC4钛合金材料的应力流动行为,分别利用万能材料试验机、霍普金森压杆设备,进行常温和高温准静态拉伸试验、动态压缩试验。通过试验得到了材料在不同应变率、温度下的工程应力-应变曲线,发现TC4钛合金材料应变硬化效应较弱,但应变率敏感性和温度软化效应较强。其次,基于试验结果,修正Johnson-Cook(J-C)本构模型和断裂准则获得MJC模型,并结合数值模拟标定J-C与MJC模型参数。最后,为校验模型和参数的有效性,采用ABAQUS/Explicit有限元软件建立卵形头弹体撞击靶体的模型,分别将J-C和MJC模型及参数嵌入到有限元程序中,进行数值仿真计算,对比撞击试验与数值模拟计算结果。研究表明,MJC模型预测的弹体弹道极限与靶体失效模式更接近于试验。

In order to describe the stress flow behavior of TC4 titanium alloy reasonably,firstly,universal material testing machine and split Hopkinson press bar(SHPB)facility were respectively used to conduct normal and high temperature quasi-static tension and dynamic compression test.Engineering stress-strain curves at different strain rates and temperatures were obtained by experiments.It reveals that the strain hardening effect of TC4 titanium alloy is weak,but the strain rate sensitivity and temperature softening effect are strong.Secondly,basing on the experimental results,the Johnson-Cook constitutive model(J-C)was modified to obtain the MJC model,and also the parameters of J-C and MJC models were calibrated by numerical simulation.Finally,in order to verify the mode and its parameters,the model of plate impacted by projectile were established with ABAQUS/Explicit finite element software.Moreover,the J-C and MJC models and parameters were embedded into the finite element program respectively for numerical simulation,and also the experimental results were compared with numerical simulations.The results show that the ballistic limit of projectile and the failure mode of plate predicted by MJC model are closer to the result of experiments than J-C model.