محمدرضا گل بهار حقیقی

Based on the available literature, investigations on the free vibration analysis of carbon nanotube reinforced composite (CNTRC) plates are limited to single layered ones with regular domains. In this thesis, firstly, the free vibration analysis of arbitrary straight sided quadrilateral laminated plates with CNTRC layers is presented. The governing differential equations are derived based on the first-order shear deformation theory using Hamilton’s principle. Four kinds of linear distribution of nanotubes along the thickness of the layers are considered, which include uniform distribution and three other functionally graded distributions. The effective material properties of the CNTRC layers are estimated according to the rule of mixtures and by considering the layers as an orthotropic material. The differential quadrature method (DQM) as an accurate and computationally efficient numerical tool is adopted to discretize the governing differential equations together with the related boundary conditions in the regular computational domain. The presented formulation and method of solution are validated by showing their fast rate of convergence and by comparing the results with those available in the literature. Afterward, detailed parametric studies have been carried out to reveal the influences of the material parameters such as carbon nano-tube volume fractions, geometrical parameters such as width to thickness ratio and aspect ratio, any kind of distribution of nanotubes along the thickness of each layer and different types of boundary conditions on the natural frequencies. In the second part, a sequence optimization is carried out to achieve the maximum natural frequency. GA as an efficient search-based algorithm is applied to perform this optimization process. The influence of the materiel and geometrical properties on the maximum natural frequency for different kinds of boundary conditions is investigated. The presented results, in addition to make clear the dynam