Shape Memory Alloys (SMAs) are a class of smart materials that exhibit a macroscopic contraction of up to 5% when heated via an electric current. This effect can be exploited for the development of novel unconventional actuators. Despite having many features such as compactness, lightweight, and high energy density, commercial SMA wires are characterized by a highly nonlinear behavior, which manifests itself as a load-, temperature-, and rate-dependent hysteresis exhibiting a complex shape and minor loops. Accurate modeling and compensation of such hysteresis are fundamental for the development of high-performance SMA applications. In this work, we propose a new dynamical model to describe the complex hysteresis of polycrystalline SMA wires. The approach is based on a reformulation of the Muller-Achenbach-Seelecke model for uniaxial SMA wires within a hybrid dynamical framework. In this way, we can significantly reduce the numerical complexity and computation time without losing accuracy and physical interpretability. After describing the model, an extensive experimental validation campaign is carried out on a 75 {\mu}m diameter SMA wire specimen. The new hybrid model will pave the development of hybrid controllers and observers for SMA actuators.

翻译：形状记忆合金是一类智能材料，在通过电流加热时可产生高达5%的宏观收缩。这一特性可被用于开发新型非常规致动器。尽管商用形状记忆合金丝具有结构紧凑、重量轻、能量密度高等优点，但其表现出高度非线性行为，具体体现为负载、温度和速率相关的复杂形状滞回及次环。对此类滞回进行精确建模与补偿是开发高性能形状记忆合金应用的基础。本文提出了一种描述多晶形状记忆合金丝复杂滞回的新型动力学模型。该方法基于对单轴形状记忆合金丝的穆勒-阿亨巴赫-泽莱克模型在混合动力学框架下的重构。通过这种方式，我们能够在不损失精度和物理可解释性的前提下显著降低数值复杂度和计算时间。在完成模型描述后，我们以直径为75微米的形状记忆合金丝样本进行了广泛的实验验证。这种新型混合模型将为形状记忆合金致动器的混合控制器和观测器的发展奠定基础。