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Nonlinear Analysis of Vibration of Tapered Piezo Electromagnetic Beam in Presence of External Permanent Magnet in Order to Energy Harvesting Improvement

Babaee Nikoo, Mohammad Javad | 2021

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 55217 (45)
  4. University: Sharif University of Technology
  5. Department: Aerospace Engineering
  6. Advisor(s): Hosseini Kordkheili, Ali
  7. Abstract:
  8. With the increasing development in the field of electronics and information technology, the required dimensions and power of electronic devices and sensors have decreased. The range of applications of these electronic devices is very large, which is the product of technological progress development. There is a problem in the development and application of such devices, the supply of electrical power used in them, especially in the set of wireless sensors, this problem is more significant.The use of piezoelectric materials is one of the methods of converting mechanical energy into electrical energy. The voltage generated by the piezoelectric material can be used to charge the capacitor or battery. Piezoelectric energy pickers are widely used in a wide range of industries, such as the aerospace industry.At first, only energy extraction from such piezoelectric harvesters was considered, and then researchers tried to improve the harvested power and output voltage of such converters. In the mechanical part, one of the proposed solutions is to use a beam with variable cross section, so that a uniform distribution of strain is created along the beam. As the strain in the direction of the beam becomes uniform, the output voltage is also uniform in the direction of the length of the beam, which will increase the output voltage throughout the beam.Also, by reducing the total weight of the beam, the ratio of output power to the weight of the piezoelectric energy picker will be optimized.Another point is that piezoelectric materials exhibit substance-dependent nonlinear behavior when excited by high amplitudes. This means that if the excitation amplitude increases, in addition to the geometric nonlinear effects or high strain, the piezoelectric material also exhibits nonlinear behavior.In addition to the above two points, the presence of a mass at the end of the beam is a factor to control the natural frequency of the beam, and by adjusting the mass, the natural frequency of the beam can be designed so that the maximum output power can be harvested at operating loads.Various measures have been taken to adjust the movement of the beam in such a way as to increase the energy extracted from it. One of the suggested methods is to use magnets around the beam oscillation environment.In order to develop the governing equations, the Euler-Bernoulli beam assumption has been used and it is also assumed that the voltage is evenly distributed on the piezoelectric surface.In this paper, a semi-analytical method for designing piezoelectric energy harvester with linear variable width despite the mass of the end point and under the influence of a permanent magnet is presented.Finally, the results of this study showed that the cross-sectional linear variable optimizes the output power-to-mass ratio. The presence of external magnets increases the nonlinear behavior of the system and also increases the amount of output power. Also, the parameters of the distance between the magnets and the resistance connected to the electrical circuit can be selected in such a way as to maximize the power taken. Of course, the presence of a point mass at the end of the beam can control the natural frequency of the system, and it can also be determined in such a way that the frequency of the piezoelectric beam is equal to the operating frequency of the environment to maximize energy recovery.
  9. Keywords:
  10. Nonlinear Vibration ; Piezoelectromagnetic (PEM)Materials ; Material Nonlinearity ; Geometric Nonlinearity ; Intertial Nonlinearity ; External Permanent Magnet ; Governing Equations

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