Prediction of thermally-controlled actuation for shape memory alloy film-based bimorph cantilevers
Prediction of thermally-controlled actuation for shape memory alloy film-based bimorph cantilevers
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DOI：
10.1088/0964-1726/23/7/075025
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发表时间：
2014-07-01
影响因子：
4.1
通讯作者：
Ercuta, Aurel
中科院分区：
文献类型：
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作者：
Craciunescu, Corneliu;Ercuta, Aurel
通过考虑马氏体相变过程中薄膜的热性质和弹性性质的变化，提出了一种用于预测沉积在固体衬底上的形状记忆合金薄膜制成的双晶片悬臂梁挠度的模型。零驱动参考温度是薄膜处于奥氏体相时的沉积或退火温度。在从这一点冷却时，双晶片中积累的热弹性应力导致双金属类型的行为，直到奥氏体-马氏体相变开始，这现在控制着驱动直到完成，当双金属驱动重新出现时。将经典的双金属恒温器模型应用于一种成分发生马氏体相变的情况，通过平均等应变和等应力相分布的边界近似，计算了加热和冷却过程中的挠度，并以Ti50.1Ni49.9薄膜/Si为例进行了研究。预测结果与Ti49.2Ni50.8/Si悬臂梁的记录挠度一致(最高温度漂移由成分变化和薄膜在相变过程中产生的应力解释)，表明马氏体相变对挠度斜率和符号有很强的影响(归因于两相的弹性常数和热常数之间的差异)。
A model is proposed for predicting the deflection of bimorph cantilevers made of a shape memory alloy film deposited onto solid substrates, by taking into account the changes in the thermal and elastic properties of the film during the martensitic phase transformation. The zero actuation reference temperature is the deposition or annealing temperature, with the film in the austenite phase. On cooling from this point, the thermoelastic stress building up in the bimorph causes bimetal-type behavior until the onset of the austenite-martensite transformation, which now controls the actuation up to its completion, when the bimetal actuation reappears. By adapting the classical bimetal thermostat model to the case when one component undergoes martensitic transformation, the deflection during heating and cooling is calculated by averaging the isostrain and isostress phase distribution bounding approximations; the case of a Ti50.1Ni49.9 film/Si was examined. Predictions in good agreement with the recorded deflection of a Ti49.2Ni50.8/Si cantilever (up to a temperature shift explained by composition change and stress developed in the film during the transformation) resulted, indicating a strong effect (attributed to the differences between the elastic and thermal constants of the two phases) of the martensitic phase transformation on the deflection slope and sign.