Refrigeration technologies based on the elastocaloric effect of shape memory alloys (SMAs) have attracted much interest in recent years. To seek for schemes that can improve the temperature span and efficiency of elastocaloric devices, this work explores more practical loading conditions (between adiabatic and isothermal) of SMAs. To account for the smoothness of the martensite phase transformation of SMAs, a general polynomial form of hardening-like function is adopted in the phenomenological multi-physics coupling framework. The modeling framework is further calibrated by measurements of the thermomechanical responses of pre-trained Ni–Ti wires. Due to the hardening-like function, the martensitic volume fraction cannot be explicitly expressed. Accordingly, a new numerical scheme is also presented in this work. Moreover, an empirical function of the maximum transformation strain is proposed based on the experimental observation, which improves the capability of the model to capture experimental data. This work aims to provide a paradigm from material characterization to theoretical modeling and numerical simulation, and then to elastocaloric cooling performance analysis of SMAs.

中文翻译：

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形状记忆合金丝的热机械响应和弹热效应

近年来，基于形状记忆合金（SMA）弹热效应的制冷技术引起了广泛关注。为了寻找能够提高弹热器件温度跨度和效率的方案，这项工作探索了 SMA 更实际的负载条件（绝热和等温之间）。为了考虑 SMA 马氏体相变的平滑性，在唯象多物理耦合框架中采用了一般多项式形式的类硬化函数。通过测量预训练 Ni-Ti 线的热机械响应进一步校准建模框架。由于类似硬化的作用，马氏体体积分数无法明确表达。因此，本文还提出了一种新的数值方案。此外，基于实验观察提出了最大转变应变的经验函数，提高了模型捕捉实验数据的能力。这项工作旨在提供从材料表征到理论建模和数值模拟，再到 SMA 的弹热冷却性能分析的范例。