压剪载荷作用下TB6钛合金的动态力学性能

Dynamic Behavior of TB6 Titanium Alloy under Shear-Compression Loading

钛合金以其轻质高强的优异力学性能被广泛应用于航空航天领域。使用Instron万能材料试验机和分离式霍普金森压杆,对TB6钛合金进行准静态和动态力学性能实验,得到了压缩、拉伸和压剪载荷作用下TB6钛合金的准静态和动态应力-应变曲线,构建了单轴压缩和纯剪切两种应力状态下的Johnson-Cook动态本构模型。结果表明,TB6钛合金的屈服应力表现出明显的拉压不对称性、应变率强化和热软化效应。使用拉压不对称因子,修正了von Mises屈服准则,修正的屈服准则可很好地预测TB6钛合金的准静态和动态屈服行为。

Titanium alloy is widely used in aerospace industry due to its excellent mechanical properties of high strength and light weight. In this paper, a quasi-static and dynamic tests of TB6 titanium alloy has been implemented with an Instron universal material testing machine and a split Hopkinson pressure bar (SHPB). Quasi-static and dynamic stress-strain curves of TB6 titanium alloy under compression, tension and shearcompression loads were obtained. Based on the data of experiment, we have established Johnson-Cook dynamic constitutive model under uniaxial compression and pure shear. The results show that, the yield stress of TB6 titanium alloy exhibits obvious tension-compression asymmetry, strain rate hardening and thermal softening effects. The von Mises yield criterion is modified by considering the asymmetric factor of tension and compression. The modified yield criterion has been proved to be accurate and suitable for predicting the quasi-static and dynamic yield behaviors of TB6 titanium alloy.