Loading...

Dynamic and Vibration Analysis of Functionally Graded Microswitches and Microresonators Based on the Strain Gradient Theory

Rahaeifard, Masoud | 2014

501 Viewed
  1. Type of Document: Ph.D. Dissertation
  2. Language: Farsi
  3. Document No: 45446 (08)
  4. University: Sharif University of Technology
  5. Department: Mechanical Engineering
  6. Advisor(s): Ahmadian, Mohammad Taghi; Firoozbakhsh, Keikhosrow
  7. Abstract:
  8. In this research, based on the strain gradient theory, mechanical behavior of functionally graded microbeams is analyzed and the results are used to investigate the static and dynamic responses of electrostatically actuated microswitches and microresonators.
    The nonlinear governing equations of motion of functionally graded microbeams are derived using Hamilton’s principle. Afterward, the nonlinear model is implemented to analyze the mechanical response of electrostatically actuated microswitches and microresonators. Pull-in instability and nonlinear vibration of these components are investigated considering the effects of squeeze film damping, mid-plane stretching and initial curvature of the microbeam. The results are compared with experimental observations as well as the results of the classical theory. This comparison indicates that the difference between the results of classical theory and experimental findings is notable while the results of the strain gradient theory are in very good agreement with experimental observations.
    Finally, according to the strain gradient theory, a new yield criterion is proposed to predict the accurate yielding load of micro scale structures. The results of this criterion are compared with those of classical based yield criteria and experimental observations. According to this comparison, the new yield criterion is able to accurately calculate the yielding load of micro scale structures while the differences between the experimental results and those given by the classical yield criteria (such as the von-Mises criterion) is considerable (up to 50 %) .
  9. Keywords:
  10. Strain Gradient Theory ; Microelectromechanical Systems (MEMS) ; Functionally Graded Materials (FGM) ; Vibrational Analysis ; Dynamic Analysis ; Yield Criterion

 Digital Object List

 Bookmark

No TOC