Low Resonant Frequency Energy Scavenging Based on Bi-Stability Structure Dynamics

从结构振动中收集能量是一种非常有希望的方法，可以潜在地取代传统上使用电池的许多应用中使用的电源。许多结构作为自然振动源，如因风荷载而摇摆的桥梁或因内部石油流动而振动的管道，这为发电提供了独特的机会。有效实施的主要挑战是开发在大多数环境中典型的低频和某种随机振动条件下最佳工作的收获装置。本项目将探索屈曲梁结构的非线性响应，作为在这些混沌、低频条件下提高功率输出的一种手段。双稳系统，如屈曲梁，自然有两个稳定状态和一个非线性动力响应，这是以前被证明是理想的非规则加载情况。这项工作试图通过研究在稳定屈曲状态之间的切换行为来提高在这些条件下的能量收集效率，以实现独特的能量采集器设计。针对无线传感器电源应用的这种设备的微型版本将通过实验和有限元分析模拟进行探索。所进行的研究将有助于引入一种新的能源收集设备，并将通过公共图书馆暑期阅读计划和当地高中研究经验推广计划在当地社区内进行合作。通过这项工作取得的研究成果和核心见解将通过出版物、会议和研讨会等传统方式广泛传播。教育外展计划将通过与路易斯维尔免费公共图书馆建立的社区参与伙伴关系，为代表不足的群体、K-12学生和普通公众提供服务。这一安排将有助于教授关键的工程概念，并通过与图书馆暑期阅读计划一起安排的几项以科学为基础的活动，促进PI与更大社区之间的直接互动。此外，PI还巩固了与当地高中科学系主任的关系，让学生参与工程主题，并招募不同的学生小组，以获得在能源收集领域工作的夏季研究经验。本研究的目标是通过为具有混沌脉冲特性的环境振动水平(40赫兹)优化设计的系统，提高MEMS规模能量收集器的真实功率清除能力。这一挑战是通过研究具有屈曲光束稳定状态切换的能量收集设计的系统动力学来实现的。将进行结构变形和相关功率生产的有限元建模，并对用于验证优化性能参数的设备进行实验测试。本项目的重点是双稳态屈曲结构的非线性动力响应，它被用来在广泛的激励频率范围内优化集成压电体中的应变/发电。所提出的屈曲结构MEMS的工作方式与其他双稳态MEMS能量收集器的工作方式完全不同，通过操纵结构的约束条件来诱导开关来产生大变形。使用在屈曲稳定状态之间切换的方法允许系统响应自然地适应振动强度。这里使用的设计在其他双稳态屈曲结构中是独一无二的，因为可以针对非常低的共振频率范围。基于相同工作原理的多节点设计迭代提供了一类潜在的新型MEMS能量收集装置，而用于描述弯曲梁稳定性切换发电的机电关系将引起更广泛的能量收集领域的兴趣。能源采集界特别感兴趣的将是描述稳定状态转换期间的应变的发电模型的开发。

Scavenging energy from structure vibrations is one highly promising method for potentially replacing power sources used in many applications that have traditionally used batteries. Many structures serve as natural vibration sources, such as bridges swaying due to wind loads or pipelines vibrating due to the oil flow within, which offer unique opportunities to generate energy. The primary challenge for effective implementation is developing harvesting devices that work optimally under the low frequency and somewhat random vibration conditions typical of most ambient environments. This project will explore the nonlinear response of buckled beam structures as a means to enhance power output under these chaotic, low frequency conditions. Bi-stable systems, such as buckled beams, naturally have two stable states and a nonlinear dynamic response, which has been previously shown to be ideal for irregular loading scenarios. This work seeks to improve energy harvesting efficiency under these conditions by investigating the behavior dictating switching between the stable buckled states for the unique proposed energy harvester design. Microscale versions of this device targeted for wireless sensor power applications will be probed through experiments and finite element analysis simulations. The research performed will help introduce a new class of energy harvesting devices, and will be supplemented with collaborations within the local community via the public library summer reading program and a local high school research experience outreach program. The research outcomes achieved through this work and core insights will be widely disseminated through the traditional means of publications, conferences, and workshops. Educational outreach plans will serve underrepresented groups K-12 students and the general public through a community engagement partnership the PI has created with the Louisville Free Public Library. This arrangement will help teach key engineering concepts and promote direct interaction between the PI and the larger community via several science-based activities arranged in conjunction with the library's summer reading program. In addition, the PI has solidified a relationship with a local high school science department chair to engage students on engineering topics, and recruit a diverse student group for summer research experiences working in the energy harvesting area.The objective of this research is to improve the real-world power scavenging capabilities of MEMS-scale energy harvesters through a system optimally designed for ambient vibration levels (40 Hz) with chaotic impulse characteristics. This challenge is approached through an investigation of the system dynamics of an energy harvesting design featuring buckled beam stability state switching. Finite element modeling of structure deformations and the associated power production will be performed, with experimental testing of devices used for validation of optimized performance parameters. The focus of this project is on the nonlinear dynamic response of bi-stable buckled structures, which is leveraged to optimize strain/power generation within integrated piezoelectric over a broad spectrum of excitation frequencies. The proposed class of buckled structure MEMS work in a fundamentally different way than other bi-stable MEMS energy harvesters, creating large deformations by manipulating the constraint conditions of the structure to induce switching. The approach of using switching between buckling stability states allows for a system response that naturally is adaptive to the vibration intensity. The design used herein is unique amongst other bi-stable buckled structures, in that very low resonant frequency ranges can be targeted. Multi-node design iterations based on the same operating principle offers a potential new class of MEMS energy harvesting devices, while electro-mechanical relationships developed to describe the power generation from buckled beam stability switching will be of interest to the broader energy harvesting field. Of particular interest to the energy harvesting community will be the development of power generation models describing strains during stability state switching.