雙穩態挫曲懸臂梁拉伸式壓電能量採集器

Abstract

壓電能量採集技術是一種能夠將環境中持續存在的微弱機械振動轉換為電能的能量擷取方法，廣泛應用於物聯網與感測裝置中。傳統的壓電懸臂梁能量採集器雖具結構簡單與製作容易之優點，卻普遍面臨頻寬狹窄與能量轉換效率不穩定等限制。為改善此問題，本研究提出一種結合雙穩態機構與拉伸式壓電元件之非線性振動能量採集器，透過結構配置導入幾何非線性與彈性耦合機制，實現擴大頻率響應的能力。本裝置由雙懸臂梁與中間壓電支撐梁組成，並設計可變長度之預壓縮機構以控制系統穩態配置，藉此觸發單穩態與雙穩態行為轉換。理論分析部分採用Euler-Bernoulli梁理論與Lagrangian能量法推導出多自由度非線性動力學模型，再結合壓電本構關係導出耦合電學模型。後續透過實驗驗證模型準確性，並分析各項參數對系統頻率響應與輸出電壓的影響。研究顯示，透過調整壓電材料的初始應變與結構配置，不僅可提升整體應變分布均勻性與能量轉換效率，亦能擴展頻率響應範圍。特別是在非線性特性影響下，系統呈現明顯的頻率非線性硬化和部分非線性軟化行為，以及穩態間的切換行為，進一步促進能量採集性能，展現出良好的應用潛力與可行性。

Piezoelectric energy harvesting is a technique capable of converting ambient low-level mechanical vibrations into electrical energy and is widely applied in IoT and sensing devices. Although traditional cantilever-type piezoelectric energy harvesters are structurally simple and easy to fabricate, they commonly suffer from narrow operational bandwidth and unstable energy conversion efficiency. To address these limitations, this study proposes a nonlinear vibrational energy harvester that integrates a bistable mechanism with a stretching-type piezoelectric element. Through structural configuration, geometric nonlinearity and elastic coupling are introduced to enhance the system's frequency response capability.The proposed device consists of two cantilever beams and a central piezoelectric supporting beam, along with a variable-length precompression mechanism that enables switching between monostable and bistable states. Theoretical analysis is carried out using Euler-Bernoulli beam theory and the Lagrangian energy method to derive a multi-degree-of-freedom nonlinear dynamic model, which is then coupled with the piezoelectric constitutive equations to formulate the complete electromechanical model. The model’s accuracy is further verified through experimental validation, and the effects of various parameters on frequency response and output voltage are analyzed.The results demonstrate that adjusting the initial strain of the piezoelectric material and modifying the structural configuration not only improves strain distribution uniformity and energy conversion efficiency, but also extends the operational frequency range. Notably, under the influence of nonlinear characteristics, the system exhibits prominent frequency hardening behavior, partial softening behavior, and state-switching dynamics, all of which contribute to enhanced energy harvesting performance and confirm the system’s promising potential for practical applications.