Electromechanical Analysis Of The Beam Piezoelectric Transducer

With the extensive use of small electronic devices, it becomes an increasingly prominent issue of self- energy supply for these small devices. It is a simple and convenient way to use piezoelectric effect to collect environmental energy in vibration. The beam piezoelectric transducer is an important type of energy harvest devices. It is difficult to provide the analytical expression for the piezoelectric effect in vibration of the piezoelectric vibrator with several qualities at the end. Current studies in this area are mostly based on experiments. There is few relevant research of the piezoelectric effect which involves frequiencies higher than the first order resonance frequency. Traditional studies on the piezoelectric vibrator of the piezoelectric transducers are mostly limited to single-step modes, which are only applicable to the cases of low environment frequencies. However, in the case of high external frequencies, single-step modes will result in a great error. In practical applications, the piezoelectric vibrator is inevitably to work in high-frequency band. The aims of this thesis are to study the beam piezoelectric cantilever and to explore the nature of the current output in a large frequency range.The thesis contains four chapters. The first chapter demonstrated the significance of harvesting energy from environment, and introduced current advances in this area.The second chapter summarized the piezoelectric effect principle and the related basic theory. Four important piezoelectric equations of different boundary conditions were listed. Static analysis of cantilever and simply supported beams are conducted and the piezoelectric effect formula under a certain deformation were obtained. The results are subsequently used in the following chapters.Chapter three analyzed the piezoelectric beam under dynamic deformation. The main vibration modes of the cantilever were modified. These modified main modes are of orthogonality in nature and satisfy the boundary conditions. Corresponding line of the vibration modes were plotted using mathematical software. The dynamic deflection of the piezoelectric cantilever was also investigated using the modified vibration modes. In addition, calculation of charge output of piezoelectric cantilever beam was demonstrated.In Chapter four, a lot of numerical calculations were conducted using the theoretical results established in previous chapters. Effective current output curves and their underlying physical meaning of piezoelectric cantilever beam with different parameters were established. Some simple comparsions with availabe results in literature were made.At the end of the thesis, current challenges and possible future research directions are discussed.