Mechanically-equivalent Response Amplifiers and Frequency Modulators for Energy-harvesting Devices

限制可部署传感和驱动解决方案发展的一个主要障碍是电力不足。使用基于压电材料的装置（采集器）从主体结构的振动转换能量已被证明是一种可能的解决方案。然而，这些能量采集器仅在窄范围的振动频率下和/或在高变形条件下有效。这大大限制了可收获功率的水平。虽然已经开发了几种方法来拓宽这些基于振动的收割机可以操作的频率，但它们的输入仍然需要振动。拟议的研究的目的是能够利用准静态（非常低的频率）的结构变形的能量，通过新的微机械设备，使用多种不稳定性（几何形状的突然转变，同时抵抗压缩载荷）的弹性元件（条，板和壳）。突然转变（突跳不稳定性）是可恢复的（弹性的）并且产生高速运动，该高速运动放大并增加了附接到变形元件的清除器的输入频率和变形幅度。这些设备然后成为电气组件（即放大器和频率调制器）的机械模拟。该研究将开发通过优化弹性元件上的材料和几何配置来控制（发生实例和事件数量）突变不稳定性的方法，这反过来又可以最大限度地提高压电能量采集器的能量传递。调查还将展示已开发的能量收集设备与结构元件的集成，以及电力管理和存储方法，以最大限度地利用当地收集的能源。所介绍的方法将允许能量的产生和转换，从未探索的范围内的准静态结构响应。该项目将允许对两名研究生进行多学科培训，并将与侧重于促进工程本科生多学科培训的教育和外联活动相结合。所提出的研究背后的假设是，在未探索的结构响应范围内的1Hz的能量收集可以通过设备来实现，该设备通过弹性元件的后屈曲响应中的不稳定过渡来放大输入信号的振幅和频率。采集器的高速率运动输入取决于机械换能器的后屈曲特性，其可以通过材料剪裁、边界条件和系统布置来控制。后屈曲行为的调节可以导致对压电振子的受控加速度输入。研究目标是推进创建所述设备所需的知识和技术，以增强压电材料在准静态结构变形下用于能量收集的功率转换能力。研究任务是：1）对各向同性和各向异性柱和圆柱体的后屈曲响应的理论和实验研究，2）通过材料定制、边界条件和系统组件来增强和控制机械换能器的高速运动，3）优化压电采集器材料和几何形状以定制输出电压信号的幅度和大小，4）原型结构部件的系统集成与评估，电源管理与存储技术的评估。这项研究工作将为材料和结构带来新的概念和机制，这些材料和结构利用内部产生的能量（应变）形成瞬态和低量级的负载，并将其转换为电力供当地使用或储存。这项研究将扩大压电材料作为功率采集器的可用范围，也将为它们在混合材料系统和结构中的使用开辟新的可能性，用于传感和致动设备的局部供电以及位移功率热电联产结构。

A major obstacle limiting the development of deployable sensing and actuation solutions is the scarcity of power. Converted energy from the vibrations of a host structure using devices (harvesters) based on piezoelectric materials has been shown to be a possible solution. However, these energy harvesters are only efficient at a narrow range of vibration frequencies and/or under high deformation conditions. This considerably limits the levels of harvestable power. While several approaches have been developed to broaden the frequencies at which these vibration-based harvesters can operate, their input still needs to be vibratory. The aim of the proposed research is to be able to harness the energy from quasi-static (very low frequency) structural deformations through novel micro-mechanical devices that use multiple instabilities (sudden transitions in geometry while resisting a compressive load) in elastic elements (strips, plates and shells). The sudden transitions (snap-through instabilities) are recoverable (elastic) and generate high-rate motion that amplify and increase the input frequency and deformation amplitude to scavengers that are attached to the deforming elements. These devices then become mechanical analogs to electrical components (that is, amplifiers and frequency modulators). The research will develop methods to control (occurrence instance and number of events) the snap-through instabilities by optimizing material and geometric configurations on elastic elements, which will in turn allow maximizing the energy transfer from piezoelectric energy harvesters. The investigation will also demonstrate the integration of the developed energy harvesting devices into structural elements, as well as power management and storage approaches to maximize use of locally harvested energy. The introduced methods will allow energy generation and conversion from the unexplored range of quasi-static structural response. The project will allow multidisciplinary training of two graduate students and will be integrated with educational and outreach activities focused on promoting the multidisciplinary training of engineering undergraduate students. The hypothesis behind the proposed research is that energy harvesting within the unexplored structural response range of 1Hz can be achieved through devices that amplify the amplitude and frequency of the input signal by means of instability transitions in the post-buckling response of elastic elements. The high rate motion input to the harvester depends on the postbuckling characteristics of the mechanical transducers, which can be controlled through material tailoring, boundary conditions, and system arrangements. Regulation of the post-buckling behavior can lead to controlled acceleration input to the piezoelectric vibrators. The research objective is to advance the knowledge and technology needed to create the noted devices to enhance the power conversion capabilities of piezoelectric materials for energy harvesting under quasi-static structural deformations. The research tasks are: 1) theoretical and experimental studies on the postbuckling response of isotropic and anisotropic columns and cylinders, 2) enhancement and control of the high rate motion of the mechanical transducers by material tailoring, boundary conditions and system assemblies, 3) optimization of the piezoelectric harvesters materials and geometry to tailor the amplitude and magnitude of the output voltage signal, and 4) system integration and evaluation in prototype structural components and evaluation of power management and storage technology. The research work will lead to new concepts and mechanisms for materials and structures that utilize the energy that develops within them (strain) form transient and low magnitude loads and convert it to electrical power for local use or storage. The research will expand the useable range of piezoelectric materials as power harvesters and will also open new possibilities for their use in hybrid material systems s and structures for local powering of sensing and actuating devices as well as displacement-power cogeneration structures.