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。这将为便携式或移动应用提供新一代智能微型阻尼器系统，结合无噪声和无抽搐操作，以及由于热、机械和电气性能的强耦合而具有额外的传感功能。由于一阶相变，SMA材料和器件表现出非线性应力-应变响应和滞后，允许在高达500 MPa和5%的大应力和应变水平下设计和控制耗散过程。由于SMA薄膜的表面体积比大，快速传热导致时间常数在毫秒级。起始材料是具有优化SE或SME性能的ti基薄膜。采用考虑相变、应变变化和热流演变的基于热力学的相场模型，通过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。将开发和评估几代SMA薄膜阻尼器系统，利用由于SE的被动阻尼，由于SME的主动阻尼以及它们的组合。将开发模型降阶策略以降低仿真复杂度。将为系统级的模型集成生成集总元素模型。将开发一个微型相机模块作为演示，以研究SMA薄膜阻尼和合适的控制策略对整个系统动力学的影响。附加功能包括固有温度和位置传感将被研究。

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.