本文係針對U型電熱式微致動器（‘U shaped electro-thermal actuator’or ‘hot-cold-beam’）及V型電熱式微致動器（V shaped electro-thermal actuator）進行疲勞實驗，配合有限元素分析軟體ANSYSTM模擬分析，探討負載功率、操作頻率、微致動器溫度及微致動器尺寸對疲勞的影響，並得到微致動器疲勞曲線（S-N curve）。此外，模擬分析微致動器之等效阻尼及阻尼比，可正確評估撓曲量或操作頻率範圍。
研究結果顯示，當負載功率較大時，微致動器溫度較高，結構內應力較大，微致動器較易發生疲勞破壞。若固定負載功率，改變操作頻率，高頻時微致動器具有較長之疲勞壽命，然此時微致動器振幅範圍較小。比較不同尺寸U型微致動器之疲勞曲線，發現於相同操作頻率及最大主應力條件下，小倍率微致動器疲勞壽期較長，然當倍率再增加時此現象則不明顯。另由結構動態分析可知U型微致動器其振動行為受空氣黏滯效應、結構與基材間摩擦、本身材料阻尼作用…等影響很大，造成微致動器阻斷頻率下降，也間接影響其疲勞壽命；而V型微致動器其結構勁度較大，阻尼作用對其運動行為影響不大。
本研究可提供微致動器設計之參考，有效提昇可靠度及疲勞破壞預測之準確度。

Fatigue analysis for planar flexural (U shaped) and bent-beam (V shaped) electro-thermal micro actuators is performed in this study. In addition to laboratorial fatigue life observations, finite element software, ANSYSTM, was adopted to interpret the S-N curve for the actuators. The influences of input power, operation frequency and temperature distribution on fatigue life are also investigated. A model of equivalent damping and damping ratio is also developed in the study and its results reveal that reasonable deflection range and operation frequency window for the micro actuators can be achieved.
Based on the results, it is concluded that as driving electrical power increases, temperature range in actuators elevates that in turn yields internal stress range; therefore, shortens the fatigue life of the actuator. At the condition of constant driving power, higher operation frequency that limits the flexural deflection for the actuator results in longer fatigue life. Size effect on fatigue life is also observed, i.e. bigger actuators tend to deliver shorter fatigue life. However, the phenomenon is not obvious as the size of the actuators is raised further. The numerically structural dynamical analysis shows important influence of camping effects on the dynamical behavior as well as the fatigue life of the U-shaped actuators. Damping effects including air viscosity, friction force and material damping reflects the reduction of cutoff frequency. However, damping effect is insignificant on V-shaped actuators due to its higher stiffness in flexural direction than its counter part of U-shaped actuators.

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