Shape Memory Alloy Film Damping for Smart Miniature Systems

本项目利用超弹性效应(SE)或热形状记忆效应(SME)的耗散机制，对新型形状记忆合金(SMA)薄膜阻尼器进行了研究、数值描述和验证。这将为便携或移动应用提供新一代智能微型阻尼器系统，该系统结合了无噪声和无冲击操作以及由于热、机械和电气特性的强烈耦合而产生的附加传感功能。SMA材料和器件由于一阶相变而表现出非线性的应力-应变响应和滞后，使得在高应力和应变水平下可以设计和控制耗散过程，应力和应变水平分别高达500 Mpa和5%。由于SMA薄膜具有较大的比表面积，快速的热传递导致了毫秒级的时间常数。起始物是TiNi基薄膜，表现出最佳的SE或SME性能。通过基于热力学相场模型的时间分辨有限元模拟，描述了相应试验结构在载荷循环过程中的耗散机制，该模型考虑了相变、应变变化和热流的演化。将开发和评估几代形状记忆合金薄膜阻尼器系统，利用SE的被动阻尼力、SME的主动阻尼力及其组合。将开发模型降阶策略以降低仿真复杂度。将生成集中元素模型，以便在系统级别进行模型集成。将开发一个微型相机模块作为演示，以研究SMA薄膜阻尼和适当的控制策略对整个系统动力学的影响。还将研究包括本征温度和位置传感在内的其他功能。

This project investigates, numerically describes and validates novel shape memory alloy (SMA) film damper devices using the dissipative mechanisms of either the superelastic effect (SE) or thermal shape memory effect (SME). This will enable a new generation of smart miniature damper systems for portable or mobile applications combining noise- and jerk-free operation as well as additional sensing functionality due to a strong coupling of thermal, mechanical and electrical properties. SMA materials and devices exhibit nonlinear stress-strain response and hysteresis due to a first order phase transformation allowing the engineering and control of dissipative processes at large stress and strain levels up to 500 MPa and 5%, respectively. Owing to the large surface-to-volume ratio of SMA films rapid heat transfer leads to time constants in the millisecond regime.Starting materials are TiNi-based films showing optimized SE or SME properties. The dissipative mechanisms during load cycling of corresponding test structures are described by time-resolved finite element simulations using a thermodynamics-based phase-field model that takes into account the evolution of phase transformation, strain changes and heat flows. Several generations of SMA film damper systems will be developed and evaluated making use of passive damping due to SE, active damping due to SME as well as combinations thereof. Strategies of model order reduction will be developed to reduce simulation complexity. Lumped element models will be generated for model integration at the system level. A miniature camera module will be developed as a demonstrator to investigate the effect of SMA film damping and of suitable control strategies on the overall system dynamics. Additional functionalities including intrinsic temperature and position sensing will be investigated.