新型阵列式微纳米俘能器的非线性力电耦合特性研究

Micro/nanoscales energy harvesters are devices that can convert vibration energy from surrounding environment to electric energy based on the flexoelectric effect of materials. This type of micro/nanoscales energy harvesters has more advantages, such as high energy conversion efficiency, easy manufacture and long service life. Therefore, energy harvesters based on flexoelectric effect will be widely used in future. In addition, array of energy harvesters can significantly increase the power output and expand the operating bandwidth. However, due to the combined effects of flexoelectric effect, surface effect, intermolecular forces and geometrically nonlinear strain, it is very difficult to understand the electromechanical coupling behaviors of array of micro/nanoscale energy harvesters. Therefore, in this research plan, theoretical models for array of micro/nanoscale energy harvesters will be developed. Both theoretical and experimental methods are used to investigate the influences of flexoelectric effect, surface effect, intermolecular forces and geometrically nonlinear strain on the electromechanical coupling behaviors of array of micro/nanoscale energy harvesters. In order to obtain the highest power output and widest operating bandwidth, the optimal geometrical configuration of energy harvester and circuit’s impedances will be given. Key factors that can affect the electromechanical coupling behaviors of array of micro/nanoscale energy harvesters are considered. Therefore, theoretical models provided in this research plan can more accurately predict the power output and operating bandwidth. Results of this research plan are useful for us to understand the electromechanical coupling behaviors of array of micro/nanoscale energy harvesters, and accumulate theories for popularization and application of array of micro/nanoscale energy harvesters.

新型微纳米俘能器利用材料的挠曲电效应，能将环境中振动的能量转化为电能，具有俘能效率高、制造简单、寿命长等优点。因此，具有广泛的应用前景。为了克服单个俘能器功率低和带宽窄的缺点，人们提出了阵列式微纳米俘能器结构的概念。然而，由于涉及到挠曲电效应、表面效应、分子间作用力及大变形等复杂因素，阵列式微纳米俘能器的力电耦合特性分析难度很大。目前，人们对阵列式微纳米俘能器力电耦合行为的认识尚不充分。本项目将建立新型阵列式微纳米俘能器非线性力电耦合特性的分析模型；通过理论分析和实验相结合，明确挠曲电效应、表面效应、分子间作用力及非线性变形对其力电耦合行为的影响机理；优化其几何构型及外电路阻抗，以提高其功率、拓宽其带宽。本项目综合考虑了影响阵列式微纳米俘能器力电耦合行为的关键因素，因此更能准确地预测其功率与带宽。项目研究成果将加深人们对新型阵列式微纳米俘能器力电耦合行为的认识，为其推广应用积累理论基础。

有效地收集周围环境中的振动能量作为电能为微/纳米机电系统（MEMS/ NEMS）供电，而无需使用电池，是一项紧迫的研究课题。在能量采集器领域，挠曲电效应有着重要应用前景。在微纳米尺度下，挠曲电效应往往比压电效应更为显著。因此，研究基于挠曲电效应的能量采集器的力电耦合行为是非常迫切和非常有意义的。本项目的主要取得了如下成果：.基于小变形理论，通过哈密顿原理导出基于挠曲电效应的微纳米俘能器的力学及电学的控制方程，给出了俘能器输出电压、输出功率及最优电阻的近似表达式。结果表明，挠曲电效应对输出电压与输出功率的贡献要大于压电效应的。当压电层长度一定时，输出电压和输出功率随压电层靠近固定端而增大。因此，可以将压电层贴在固定端以获取最大功率；附加质量块增大输出电压、输出功率及能量收集效率，然而使俘能器的固有频率减小。.圆形薄板是另一种常用的微纳米俘能结构，通过哈密顿原理导出了挠曲电圆形薄膜俘能器的控制方程，并通过 Galerkin 法,得到了输出电压、输出功率及最优电阻的近似解析解。 结果表明，输出功率和输出电压依赖于挠曲电层的内外半径，存在最优的内外半径使输出电压和输出功率最大。.基于几何非线性变形理论，通过能量法导出基于挠曲电效应的微纳米俘能器的非线性力学及电学的控制方程。以悬臂梁为例，将曲率非线性考虑在内，给出了两种常用悬臂型俘能器结构的降阶模型。通过时间多尺度法给出了俘能器输出电压、输出功率及最优电阻的数值解。结果表明，在大幅振动时，非线性曲率对输出电压的影响非常显著，最优外电阻依赖外激励幅值。.单个微纳米俘能器功率低，频带窄，很难为纳米装置提供充足的电能。而阵列式微纳米结构具有能量密度高、频带宽的优点。给出了并联和串联阵列式俘能器的输出电压的近似解析解。结果表明，阵列式俘能器的输出功率与带宽依赖于附加质量块的梯度。串联和并联阵列式俘能器的最大输出功率几乎一致，然后，最优外电阻值差异巨大。