The work presents a thermomechanical model for polycrystalline NiTi-based shape memory alloys developed within the framework of generalized standard solids, which is able to cover loading-mode dependent localization of the martensitic transformation. The key point is the introduction of a novel austenite-martensite interaction term responsible for strain-softening of the material. Mathematical properties of the model are analyzed and a suitable regularization and a time-discrete approximation for numerical implementation to the finite-element method are proposed. Model performance is illustrated on two numerical simulations: tension of a superelastic NiTi ribbon and bending of a superelastic NiTi tube.

中文翻译：

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NiTi基形状记忆合金的热机械模型涵盖马氏体相变的宏观局部化

该工作提出了在广义标准固体框架内开发的多晶 NiTi 基形状记忆合金的热机械模型，该模型能够涵盖马氏体转变的加载模式相关局部化。关键是引入了负责材料应变软化的新奥氏体-马氏体相互作用项。分析了模型的数学特性，并提出了对有限元方法进行数值实现的合适的正则化和时间离散近似。模型性能通过两个数值模拟进行说明：超弹性 NiTi 带的张力和超弹性 NiTi 管的弯曲。