Date of Award

Summer 8-2020

Document Type


Degree Name

Master of Science (MS)


Mechanical & Aerospace Engineering


Mechanical Engineering

Committee Director

Tian-Bing Xu

Committee Member

Gene Hou

Committee Member

Mileta Tomovic


Energy harvesting technologies are integrated into various modern devices and systems. These systems include Artificial Intelligence (AI) systems, Internet of Things (IoT), various types of energy harvesters are integrated in many engineering applications such as automotive, aerospace and ocean engineering. In order to develop a fully functioning stand-alone system, it is essential to integrate it with a built in power source such as a battery or a power generator. Also, in many situations, city power sources might not be available. Therefore, reliable, renewable and sustainable local power generators are desired. Piezoelectric energy harvesting (PEH) technologies, which are piezoelectric material-based devices, are one of the best candidates for this job. Piezoelectric energy harvesters convert mechanical energy from vibrating or moving objects to electrical energy. These devices have the highest capability of designing self-powered systems as they are not weather dependent and they are capable of harvesting both small or large mechanical movements into electrical energy. The piezoelectric materials are materials that generate electrical charges when mechanical stress or force is exerted on them. On the other hand, they deform when an electric voltage is applied to them. The piezoelectric-based energy harvesters are small and effective devices that promise future engineering systems to be more intelligent, reliable and environmentally friendly. Designing a piezoelectric device is cumbersome, and it is indispensable to have a comprehensive understating of many engineering disciplines before delving into designing a new device or redesigning an existing device. These disciplines include mechanical engineering, electrical engineering, materials sciences, and device physics. In this thesis, comprehensive mathematical and experimental investigations were done for modeling piezoelectric multi-later stacks and Flextensional Energy Harvesters in resonance and in off- resonance modes. For the resonance mode, mathematical and variational approaches were used to modeling a selected piezoelectric multi-layer stack found in the market; the models are a static model, single degree of freedom model (SDOF), a distributed parameter model and a finite element model for the resonance mode, a finite element model (using ANSYS) was used to model a single and a multiple stage Flexteisonal Energy Harvester. To validate off-resonance results, previously published experimental results were used; however, for the resonance mode an experiment was carried out to validate the numerical model's results for the multi-stage Energy Harvester. As for the single stage Flextensional Energy Harvester, previously published experimental results were used to validate the finite element model. The advantages and disadvantages of different models and approaches are compared and discussed.


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