Superelastic and cyclic response of NiTiSMA at various strain rates and temperatures
Superelastic and cyclic response of NiTiSMA at various strain rates and temperatures
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DOI：
10.1016/j.mechmat.2005.07.004
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发表时间：
2006-05-01
影响因子：
3.9
通讯作者：
Guo, WG
中科院分区：
文献类型：
--
作者：
Nemat-Nasser, S;Guo, WG
为了表征NiTi形状记忆合金（SMAs）在不同温度和应变速率下的热力学响应，特别是超弹性行为，我们使用Instron伺服液压试验机和UCSD的增强型Hopkinson技术对圆柱形样品进行了一系列准静态和动态单轴压缩测试。在77-400 K的初始温度范围内，应变速率从10(-3)/s到约4200/s。研究了退火温度对疲劳响应的影响。研究结果表明：(1)NiTi sma的相变应力和耗散能与退火温度有关；(2)在循环加载过程中，一个周期内的耗散能趋于最小稳定值，循环加载导致合金具有稳定的超弹性行为；(3)与准静态循环试验相比，反复动态试验对合金超弹性环形状和耗散能量的影响较小；(4)该材料的超弹性性能对温度的敏感性大于对应变速率的敏感性；在非常高的加载速率下，NiTi sma显示出与普通钢相似的性能，正如第一作者及其同事所证实的那样。(c) 2005 Elsevier Ltd版权所有。
To characterize the thermomechanical response, especially the superelastic behavior of NiTi shape-memory alloys (SMAs) at various temperatures and strain rates, we have performed a series of both quasi-static and dynamic uniaxial compression tests on cylindrical samples, using an Instron servohydraulic testing machine and UCSD's enhanced Hopkinson technique. Strain rates from 10(-3)/s to about 4200/s are achieved, at initial temperatures in the range of 77-400 K. The influence of the annealing temperature on the fatigue response is also examined. A few noteworthy conclusions are as follows: (1) the transformation stress and the dissipated energy of NiTi SMAs depend on the annealing temperature; (2) in cyclic loading, the dissipated energy over a cycle tends to a minimum stable value, and cyclic loading leads to a stable superelastic behavior of the alloy; (3) repeated dynamic tests of the alloy produce smaller changes in the shape of the superelastic loop and in the dissipated energy than do the quasi-static cyclic tests; and (4) the superelastic behavior of this material has stronger sensitivity to temperature than to strain rate; at very high loading rates, NiTi SMAs show properties similar to ordinary steels, as has been established by the first author and coworkers. (c) 2005 Elsevier Ltd. All rights reserved.