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Dynamic Analysis of FGM Micro Beam With Piezoelectric Patches Under Electric Force

Hosseinzadeh, Ali | 2010

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 40473 (08)
  4. University: Sharif University of Technology
  5. Department: Mechanical Engineering
  6. Advisor(s): Ahmadian, Mohammad Taghi
  7. Abstract:
  8. In this research, a functionally graded microbeam bonded with piezoelectric layers is analyzed under electric force. Static and dynamic instability due to the electric actuation is studied because of its importance in micro electro mechanical systems, especially in micro switches. In order to prevent pull-in instability, two piezoelectric layers are used as sensor and actuator. A charge amplifier is used to supply input voltage of the actuator from the output of the sensor layer. Using Hamilton's principle and Euler-Bernoulli theory, equation of motion of the system is obtained. It is shown that the load type (distributed or concentrated) applied to the microbeam from the piezoelectric layer, depends on the shape of the actuator layer (E.g. rectangle, triangular…). Finite element method is implemented for evaluation of displacement field in the microbeam and Dynamic response of the microbeam under electric force is calculated using finite difference method. Effect of squeeze film damping on pull-in voltage and time-response of the system is considered using nonlinear Reynolds equation. Results are verified for simple cases with previous related studies in the literature and good agreements were achieved. Effect of several parameters such as gain value between piezoelectric sensor and actuator layer, profile of functionally material, and geometry of the system is considered on dynamic properties of the micro beam especially on pull-in instability. Results found indicate that increasing gain value between sensor and actuator enhances stiffness of the system and will raise pull-in voltage. Material distribution of the functionally graded material is designed in such a way that results in a specific pull-in voltage. The dependency of pull-in voltage on parameters explained in the above can be used in designing micro switches with desired excitation voltage. In addition, in the cases that pullin phenomenon is undesired, piezoelectric materials can effectively been used to suppress instability
  9. Keywords:
  10. Microelectromechanical Systems (MEMS) ; Piezoelectric Materials ; Pull-in Phenomenon ; Functionally Graded Materials (FGM)

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