探討拉脹結構對於拉伸式非線性壓電能量採集器之性能影響

Abstract

傳統懸臂梁式壓電能量採集器具有頻寬狹窄、應變分佈不均及發電效率偏低等問題，限制其於實際應用中的能量轉換效能與穩定性。本研究提出一種基於拉脹結構之雙夾持拉伸式壓電能量採集器，採用SUS301不鏽鋼梁作為主體基梁，其自由端連接PVDF壓電材料，並於下方黏貼以PLA製成之拉脹結構，形成兼具柔性與幾何非線性的彈性梁。本研透過ANSYS Workbench、APDL建立三維有限元素模型，模擬幾何結構與材料參數對系統響應之影響，並製作原型進行實驗驗證。於ANSYS中進行模態、靜態與暫態分析，並探討七種不同參數之拉脹結構採集器與無拉脹結構採集器，分別藉由調整拉脹結構厚度與壓電片厚度使各模型第一模態共振頻率一致，作為比較基準。接著製作無拉脹結構採集器與拉脹結構採集器原型，於 0.3 g至0.5 g 掃頻激振加速度下量測電壓、位移響應並與暫態模擬比對；模擬能準確預測峰值頻率與幅值，驗證模型可靠，但由於壓電片僅具單軸壓電效應即"e_32 遠小於e_31，因此拉脹結構採集器在實驗結果中較無明顯的效能提升，凸顯雙向壓電材料對能量耦合的重要性。最後，在理想條件e_32 = e_31 下進行純模擬評估，並透過靜態分析選出於不同參數組的拉脹結構採集器在橫向應力和縱向應力表現較佳的三組拉脹結構採集器與無拉脹結構採集器之定頻暫態響應；結果顯示最佳參數組拉脹結構採集器於0.5 g激振時電壓可達8.87 V，較無拉脹結構採集器提升4.01倍，並於最佳負載 10 MΩ下達到最大功率54.4 µW，增幅3.4倍。

Conventional cantilever type piezoelectric energy harvesters suffer from narrow operational bandwidth, non-uniform strain distribution, and low power conversion efficiency, all of which undermine practical performance and stability. To address these drawbacks, this study proposes a clamped clamped tensile auxetic piezoelectric energy harvester (APEH). The device consists of an SUS301 stainless steel beam bonded to a PVDF piezoelectric layer at its free end, with a PLA auxetic lattice attached beneath to create a flexible beam that exhibits pronounced geometric nonlinearity. A three dimensional finite element model was developed in ANSYS Workbench and APDL to explore the influence of geometry and material Parameters, and prototypes were fabricated for validation. Seven auxetic designs with different Parameter sets, together with one non auxetic harvester, were analyzed. By jointly adjusting the auxetic lattice and PVDF thickness, the first bending mode frequency of every model was aligned to provide a fair comparison baseline. Prototypes of the non-auxetic and auxetic harvesters were tested under base excitation sweeps from 0.3 g to 0.5 g. Transient simulations closely reproduced the measured peak frequencies and amplitudes, confirming model reliability. However, because the PVDF film has an almost negligible transverse piezoelectric coefficient (e_32 ≪ e_31), the auxetic prototype showed little performance gain, underscoring the need for biaxial piezoelectric materials to maximize coupling. Under the ideal condition e_32 = e_31 , purely numerical studies were conducted. Static analyses identified three auxetic configurations with the best combination of transverse and longitudinal stresses; their steady state responses were compared with the non-auxetic baseline. The optimal auxetic harvester achieved 8.87 V at 0.5 g, 4.01 times higher than the device without the auxetic structure, and produced 54.4 µW at the optimal 10 MΩ load, and 3.4 times increase.