不同应变率下Ni-Ti形状记忆合金压缩力学行为分析

Analysis of the Compressive Mechanical Behavior of Ni-Ti SMA at Various Strain Rates

为了研究Ni-Ti形状记忆合金在不同应变率下的压缩力学行为，通过分离式Hopkinson杆实验装置分别对不同Ni—Ti形状记忆合金试样进行了动态压缩试验。实验中应变率变化范围为10^2／s—10^4/s。从压缩试验结果分析中发现：Ni-Ti形状记忆合金的相变屈服应力和位错屈服应力均随着试验温度和应变率的增加而增加，并且当应变率增加到10^4／s数量级时，应力—应变曲线中的应力平台将消失，此时材料的变形行为将类似于一般金届材料。

In order to understand the compressive mechanical behavior of Ni-Ti shape-memory alloy （SMA） at various strain rates, a series tests were performed. The dynamic compressive response of a Ni-Ti shape-memory alloy was investigated at various strain rates, using a modified split Hopkinson bar. The range of strain rates was from 10^2/s to 10^4/s. The dynamic deformation behavior of Ni-Ti shape-memory alloys was discussed and a few noteworthy conclusions were as follows： The phase yield limit and dislocation yield limit increased with increasing strain rate, and the stress-plateau was disappearing when strain rate reached 10^4/s.