Electromechanical Behaviors Of The Piezoelectric Composite Beam-type Energy Harvester

With the development of wireless network technology and portable electric devices technigue, the supply of permanent and uninterrupted electric energy for the micro-electromechanical systems has become an urgent problem. Due to the advantages of simple construction, high energy harvesting efficiency and easy miniaturization, the energy harvesting technology based on piezoelectric materials is now becoming a hot topic in the field of micro-electromechanical energy supply. In this thesis, theoretical methodology is developed to analyze the electromechanical behavior of the piezoelectric composite beam-type energy harvester. Based on the3D piezo-elasticity theory, the mechanical model of unimorph, bimorph and multilayered composite beam-type piezoelectric energy harvester have been constructed. The effect of boundary conditions and interfacial properties on the electromechanical behavior of the piezoelectric composite beam has been investigated. An effective way is proposed to adjust the natural frequency of the structure in different vibrating environment. The effect of interfacial property on the elastic field and electric field in both static and dynamic cases is also studied. It can be seen that the natural frequency of the harvester structure can be adjusted by changing the stiffness of the elastic support. A high efficiency can be reached by making the harvester to be worked under the main frequency of the environment. It is noted that the interface defect has a significant effect on the electromechanical behaviors of the harvester structure in static and dynamic conditions. In the end, a higher order zigzag theory has been employed to analyze the multilayered magneto-electro-elastic composite beams. The distributions of the physical quantities in the piezoelectric/piezoeleciric, piezoelectric/piezomagnetic and piezoelectric/piezomagnetic/elastic composite beams in static deformation have been studied. In this analysis, the shearing stress satisfies the continuity condition at each interface. The presented analysis provides a more accurate way in solving the multi-field coupling problems.