عنوان مقاله [English]
Due to the rapid development of nanotechnology, nano-plates are used in MEMS or NEMS for their superior mechanical, thermal and electrical properties. The dynamic behavior of nano-plates used as thin film elements requires a two-dimensional nano-structure analysis. Hence, one must consider small scale effects in order to refine classical theories and derive the governing equations for these structures. The scale effects are accounted for by
considering internal size as a material parameter. The local (classic) continuum theory neglects the effects of long-range load on the motion of the body, and long range inter atomic interactions. Therefore, the internal scale
is neglected. Nonlocal linear theory, which has both features of lattice parameter and classical elasticity, could be considered a superior theory for modeling nano-materials.
The nonlocal theory of Eringen is a well-known continuum mechanics theory to account for small scale effects by specifying stress at a reference point as a function of the strain field at every point in the body. Many papers dealing
with the analysis of nano-structures have been published on this topic, but, in many of the papers, the solutions of the governing equation are based on numerical methods and approximate analytical methods, like the Navier type
solution method. Hence, no exact closed-form solution is available in the literature for the free vibration analysis of nano-plates under various boundary conditions.
In this paper, the exact analytical solution proposed by Hosseini-Hashemi et al. is employed to solve the governing equations of motion of a rectangular nano-plate for nonlocal Mindlin theory. To this end, equations of motion are
derived via equations of momentum balance. Introducing a set of auxiliary and potential functions, the governing equations are decoupled for transverse vibration analysis. By transforming the displacement variables into known
functions, the problem leads to a soluble form without any approximations. The solution of natural frequencies is obtained for Levy-type boundary conditions, and, in order to confirm the reliability of the method considered, the results are compared with those reported in the literature. Also, the effects of nonlocal parameters, aspect ratio, thickness to length ratios of the plate and different boundary conditions on vibration frequencies are investigated.