周元昉臺灣大學:機械工程學研究所吳亮潔Wu, Liang-ChiehLiang-ChiehWu2010-06-302018-06-282010-06-302018-06-282008U0001-2007200813285500http://ntur.lib.ntu.edu.tw//handle/246246/187024微機電系統(Micro-electro-mechanical system)中對於可經由外界施加驅動電能產生熱能，並利用材料熱膨脹差異產生作動的致動器，一般稱之為電熱式微致動器(Electro-thermal microactuators)。本研究目的為掌握熱致動器其輸入電流與輸出位移之間動態關係，並由控制輸入熱能以產生預期熱致動行為，因電阻器產生熱功率的型式，輸入電流與產生熱功率具非線性關係，故輸入電流與引致的變形之間亦為非線性，若期望熱致動器直接由輸入電流信號而產生預期的致動行為實屬不易，在此整合主動式熱沉以達成控制之目的。 熱致動器的基本方程式為熱彈性體的運動方程式與固體熱傳能量平衡方程式，其中位移場與溫度場彼此相互影響，針對此熱彈性耦合動態問題，利用特徵函數展開法可進行求解，並對熱彈性耦合效應進行量化分析。因輸出位移受到溫度場一階動態效應的影響，由簡單的固體一維熱傳導可知影響動態特性的系統參數，並可分析邊界熱對流與熱輻射效應對熱傳動態特性的影響。於利用直流(DC)與交流(AC)複合輸入電流驅動的熱致動器，利用主動式熱沉可移除熱功率的非線性項對位移的影響，如此熱致動器可單獨由正比於輸入電流時間變化的熱功率進行驅動。在整合主動式熱沉的控制方式上，藉由了解主動式熱沉的動態控制方式，可得到主動式熱沉作用下針對熱致動器輸入熱功率的控制方式。 為驗證所發展方法的適用性，利用微加工方式製作雙層複合懸臂樑型式熱致動器，並整合目前在發展與應用上皆已成熟的塊體型式熱電致冷器作為主動式熱沉，利用可量測熱致動器動態特性的量測系統進行動態行為實驗。實驗針對直流與交流複合輸入電流信號，其中交流信號為單頻，自由端量測的速度波型與模擬相近，位移振幅則為模擬的90.4 %；主動式熱沉可降低二倍頻熱能對動態位移的影響，即其產生的位移振幅衰減為原來的46.5 %。交流信號為雙頻的量測結果與預期有所差異，此推測為主動式熱沉的控制方式，當輸入電流超出線性範圍所產生的非線性效應所致。In the micro-electro-mechanical systems (MEMS) regime, thermal actuators have been known for its advantages of high output force, low driving voltage and simple fabrication processes. This dissertation focuses on the dynamic control of the thermal actuation. For thermal actuators using heat resistor effect, the relation between input current and output heat is nonlinear, which also makes the relation between input current and output displacement nonlinear. To make the dynamic control feasible, a proper active heat sink is provided. A theoretical model taking into account the thermoelastic coupling is first developed. The thermoelastic coupling arises from the coupling of the strain rate to the temperature field of the heat transport. The dynamic responses for a harmonically varying thermal load are simulated using the eigenmode expansion method. The thermoelastic coupling effects on the resonant frequency and the quality factor are evaluated for each eigenmode resonance of the deflection. In addition, the dynamic characteristic of thermal actuators is dominated by the first-order characteristic of the heat conduction. Influences of thermal cut-off frequency, thermal diffusivity, thermal convection, and thermal radiation on the dynamic thermal responses are then studied. The active heat sink utilizes the commercial thermoelectric cooler. For thermal actuators operating under a DC/AC composite input current, active heat sink is designed to eliminate the effect of the nonlinear heat on the displacement. Therefore the thermal actuators can be actuated synchronously with the input current. Based on the control equations of the active heat, the scheme to control the input heat of thermal actuators is proposed. A bimorph micro-cantilever beam was fabricated using micromachining techniques. Dynamic responses of thermal actuators were measured using laser Doppler vibrometer. For DC/AC composite input current with AC component being a single-frequency sinusoidal waveform, the measured waveform of the tip velocity is generally agreed with the simulation. The displacement amplitude is 90.4% of the simulated one. The influence of the generated double-frequency heat on the displacement can be reduced by incorporating the active heat sink. The displacement amplitude from double-frequency heat is reduced to 46.5 %. For input current with AC component composed of two sinusoidal frequencies, the displacement stemmed from the generated nonlinear heat can also be reduced with discrepancies from the simulation. In this study, the thermo-mechanical behavior of thermal actuators was investigated theoretically and experimentally. The developed method for the dynamic control of the thermal actuators was also verified. The obtained results provide insights which enable and facilitate further optimization of the dynamic control of thermal actuators.致謝 i文摘要 ii文摘要 iv錄 vi目錄 ix目錄 xv號表 xvi一章 緒論 1 1-1 研究動機與內容介紹 1 1-2 文獻回顧 2 1-2-1 熱致動器的操作原理與型式 2 1-2-2 熱致動器的熱致動行為研究 4 1-2-3 熱致動器的應用發展 6 1-3 本文內容 9二章 熱致動器之基本方程式 12 2-1 線性熱彈性基本方程式 12 2-1-1 線性熱彈性系統的特徵函數特性 15 2-2 雙層複合懸臂樑型式熱致動器之基本方程式 17 2-2-1 運動方程式的建立 17 2-2-2 熱傳方程式的建立 20 2-3 週期性內熱源下的動態響應 22 2-4 熱致動器的動態響應數值模擬與熱彈性耦合分析 29 2-4-1 雙層複合樑型式熱致動器的材料對熱彈性耦合效應的影響 32 2-5 本章歸納結論 33三章 熱致動器之動態熱傳特性分析與一維熱傳下之控制方程式 34 3-1 固體熱傳的一階系統動態特性 34 3-1-1 數值模擬 38 3-2 熱對流與熱輻射效應對動態熱傳特性的影響 40 3-3 一維固體熱傳下的熱致動器控制方程式 44 3-4 本章歸納結論 47四章 整合主動式熱沉的熱致動器輸入熱功率控制方式 48 4-1 熱致動器的輸入熱源方式 48 4-2 熱電效應與熱電致冷器簡介 50 4-2-1 熱電效應簡介 50 4-2-2 熱電致冷器的構造簡介 51 4-3 主動式熱沉之控制方程式 52 4-3-1 主動式熱沉的穩態分析 58 4-3-2 主動式熱沉的動態分析 60 4-4 整合主動式熱沉的熱致動器輸入熱功率控制方式 65 4-5 整合主動式熱沉的熱致動器操作模擬 67 4-6 本章歸納結論 71五章 整合主動式熱沉之熱致動器動態行為實驗 72 5-1 複合懸臂樑型式熱致動器的設計與製作 72 5-2 熱致動器動態量測系統的組裝 76 5-3 熱致動器的量測 77 5-3-1 熱致動器輸入熱功率與輸出位移之間的動態關係 78 5-3-2 整合主動式熱沈的熱致動器動態行為-單頻輸入電流 81 5-3-3 整合主動式熱沈的熱致動器動態行為-雙頻輸入電流 83六章 結論與建議 85考文獻 88錄A 94錄B 95圖 98表 1987534941 bytesapplication/pdfen-US熱致動器特徵函數展開法熱彈性耦合效應熱電致冷器主動式熱沉thermal actuatorseigenmode expansionthermoelastic couplingthermoelectric cooleractive heat sinkthesishttp://ntur.lib.ntu.edu.tw/bitstream/246246/187024/1/ntu-97-D87522022-1.pdf