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主要障碍是电力的稀缺性。利用基于压电材料的装置（收割机）从主机结构的振动中转换能量已被证明是一种可能的解决方案。然而，这些能量收集器仅在狭窄的振动频率范围和/或高变形条件下有效。这在很大程度上限制了可收集能量的水平。虽然已经开发了几种方法来扩大这些基于振动的收割机可以工作的频率，但它们的输入仍然需要振动。拟议研究的目的是能够利用准静态（非常低频）结构变形的能量，通过新型微机械装置，在弹性元件（条，板和壳）中使用多种不稳定性（在抵抗压缩载荷时几何形状的突然转变）。突然转变（弹跳不稳定性）是可恢复的（弹性），并产生高速运动，放大和增加输入频率和附着在变形元件上的清除器的变形幅度。然后，这些设备成为电子元件（即放大器和频率调制器）的机械类似物。该研究将通过优化弹性元件的材料和几何结构来开发控制（发生实例和事件数量）卡通不稳定性的方法，这反过来将允许最大限度地从压电能量收集器传递能量。调查还将展示将开发的能量收集设备集成到结构元件中，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量。所介绍的方法将允许从未开发的准静态结构响应范围产生和转换能量。该项目将允许对两名研究生进行多学科培训，并将与教育和推广活动结合起来，重点是促进工程本科生的多学科培训。提出的研究背后的假设是，在未开发的1Hz结构响应范围内，可以通过通过弹性元件屈曲后响应中的不稳定转变来放大输入信号的幅度和频率的装置来实现能量收集。输入到收割机的高速率运动取决于机械换能器的屈曲后特性，这可以通过材料剪裁、边界条件和系统安排来控制。调整后屈曲行为可以控制压电振子的加速度输入。研究目标是推进所需的知识和技术，以创建注意到的设备，以提高压电材料的能量转换能力，用于准静态结构变形下的能量收集。研究任务是：1)各向同性和各向异性柱和圆柱的屈曲后响应的理论和实验研究；2)通过材料裁剪、边界条件和系统装配来增强和控制机械换能器的高速率运动；3)优化压电收集器的材料和几何结构，以定制输出电压信号的幅度和幅度；4)原型结构件系统集成与评估，电源管理与存储技术评估。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其内部产生的能量（应变）形成瞬态和低量级负载，并将其转换为电能供当地使用或储存。这项研究将扩大压电材料作为能量收集器的使用范围，也将为它们在混合材料系统和结构中的应用开辟新的可能性，这些系统和结构用于传感和驱动装置的局部供电，以及位移-动力热电联产结构。

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.