以實驗驗證兩種模型應用於旋轉磁激振外力作用下之能量擷取研究

Experimental Validation of Two Approaches Adopted for Examining Harvesting Energy from Rotary Magnetic Plucking Dynamics

蕭又仁(Yu-Jen Hsiao)

指導教授 ： 舒貽忠

國立臺灣大學/工學院/應用力學研究所/碩士(2019年)

https://doi.org/10.6342/NTU201902473

摘要

本論文主要介紹用於旋轉環境下磁力激振能量擷取的兩種不同理論並以實驗驗證。其中能量擷取裝置包括安裝於固定基座上之雙層壓電片，並在其自由端固定一磁鐵，透過非接觸式旋轉磁力引起壓電懸臂樑振動進而擷取能量。第一種理論假設端點位移極小可忽略，並取兩磁鐵間相互作用力中的共振模態來作為振動共振模態方程式之外力項，而第二種理論則是取兩磁鐵間相互作用力之原始型式作為振動共振模態方程式之外力項。筆者也準備了兩種實驗方法來驗證兩種理論，第一種為變動兩磁鐵間直線距離，同時保持磁鐵旋轉半徑固定，第二種則是變動磁鐵旋轉半徑，兩磁鐵間直線距離保持固定。而不論實驗如何設置均顯示出第一種理論與實驗結果之頻率響應皆能很好的吻合。然而，對於第二種理論的預測與實驗結果一致，該理論僅在第一種實驗設置中當兩磁鐵間距與磁鐵旋轉半徑比率較大時符合。此外，在第二種實驗設置中，理論與實驗有明顯差異。而對於此現象作出的解釋為包含無限模態之脈衝力可能不適合直接應用於振動之共振模態方程式。

關鍵字

壓電 ； 磁力激振 ； 共振模態 ； 兩磁鐵直線距離 ； 磁鐵旋轉半徑

並列摘要

The thesis presents an experimental validation of two different theories adopted for examining harvesting energy from rotary magnetic plucking dynamics. The energy harvester device includes a piezoelectric bimorph mounted on a stationary base with a magnet attached to its free end. Energy is harvested by vibration of beam induced by non-contact rotary magnetic plucking. Assuming small tip displacement, the first theory estimating the harvested power is based on the fundamental mode of the magnetic interaction force applied to the resonant modal formulations of vibration. Instead, the second theory chooses the original form of the magnetic interaction force as the driving force to the resonant modal formulation of vibration. Two kinds of experimental setup are prepared for validating these two approaches. The first one chooses varying the distance of two magnets while keeping the radius of revolution fixed. The second one chooses varying the radius of revolution while keeping the distance of two magnets fixed. The results show that the first theory agrees quite well with the experimental rotary frequency response no matter what setups are prepared. However, the predictions based on the second theory are found in agreement with experimental observations only in the first setup with larger ratio of magnetic distance to the radius of revolution. In addition, there are significant deviations between theory and experiment for the second setup where the radius of revolution is changed under the fixed distance between two magnets. An explanation for such discrepancies is that the impulsive force containing infinite modes may not be suitable to be directly applied to the resonant model formulation of vibration.

並列關鍵字

Piezoelectric ； Magnetic Plucking ； resonant mode ； magnetic distance ； radius of revolution

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