فهرست مطالب y. tadi beni

In this paper, the thermo-mechanical buckling analysis of a non-homogeneous open cylindrical shell reinforced with single-walled carbon nanotubes with a uniform/non-uniform distribution on an elastic foundation under thermal andmechanical loads has been addressed. Using the minimum energy principle, the governing differential equations of this system are derived and in order to determine the properties of the reinforced composite shell, the modified mixtures law has been used. It is assumed that the properties of single-walled carbon nanotubes are acquired from molecular dynamics simulation. It is also assumed that the material properties of the reinforced carbon nanotube composites are linear in the thickness and are defined based on mixture law via a micro-mechanical model in which the nanotube performance parameter is considered. After solving these equations, the effects of geometric characteristics of the shell and material properties on the critical load and critical temperature of shell buckling are investigated.

In this work, the spectral collocation method based on Chebyshev polynomials is developed and utilized for analysis of static, free vibration, and dynamic behavior of one and two-dimensional solid structures. The main objective of the work is to introduce the spectral collocation method with Chebyshev polynomials as a powerful numerical method for solid mechanic analysis. To show the advantage and effortlessness of this method, one and two-dimensional solid structures as case studies were considered and the spectral collocation method was directly applied to the analysis and the governing equation was solved. Moreover, the homogeneous material properties and functionally graded material properties were analyzed to show the capability of the introduced method for solving the more complicated equations of motion. The results obtained for each case were compared with analytical and numerical results presented in the literature and some results were also compared with ANSYS. The results showed that the presented method has very good accuracy and efficiency to solve structural-mechanical properties.

The effects of flexoelectricity on thermo-electro-mechanical behavior of a functionally graded electro-piezo-flexoelectric nano-plate are investigated in this paper using flexoelectric modified and the Kirchhoff classic theories. Moreover, using the variation method and the principle of minimum potential energy for the first time, the coupled governing nonlinear differential equations of the nano-plate and their associated boundary conditions are obtained.  The functionally graded nano-plate is modeled using a power law equation along the plate thickness direction. The nano-plate behavior is analyzed under mechanical, electrical, and thermal loadings with different boundary conditions. It should be noted that the direct and reverse flexoelectric effects under different loading conditions were investigated.  Finally, the important quantities such as: the nano-plate deflection, the induced electrical voltage for different values of the length parameter, the power index related to the functionally graded behavior model and the geometric ratio parameter are determined. The results indicate that in the presence of flexoelectricity, the rigidity of the nano-plate increases. Also, the deflection and the generated electric potential along nano-plate thickness decreases. Finally, induced polarization decreases as a linear temperature variation is applied on the nano-plate.