Mohammad Reza Golbahar

In this thesis, the effects of a cutout and thermal environment on the three-dimensional vibration characteristics of functionally graded (FG) cylindrical micropanels with different boundary conditions are investigated. The micropanel material properties are assumed to be temperature-dependent and graded in the thickness direction. The motion equations are derived using Hamilton's principle based on the modified strain gradient theory (MSGT) in combination with the three-dimensional elasticity theory. The frequency equations are derived using the Chebyshev-Ritz method. The multiple boundary conditions are implemented by suitably choosing the Ritz basis functions. The reliability and accuracy of the results are confirmed by comparing them with available solutions in the open literature. Finally, the effects of material length scale parameter, material gradient index, thickness-to-mean radius ratio, cutout length to micropanel length ratio, elastic foundation, uniform and linear temperature rise, and boundary conditions on the natural frequencies and mode shapes of the micropanels are carried out and discussed. The results showed that the natural frequency of MSGT and MCST are higher than the classical theory; as the temperature increases, the natural frequency decreases and the effect of the cut-out on the natural frequency varies according to different boundary conditions. In addition, in micro dimensions, classical theory is not efficient and appropriate theories should be used.