Sharif Digital Repository

For studying the hygrothermal deformation of generally laminated composite platesunder uniform temperature change and uniform moisture absorption change, by starting from the reduced form of elasticity displacement field for a long flat laminate, an analytical method is developed in order to accurately calculate the interlaminar stresses near the free edges of the laminate. The constant parameters appearing in the reduced displacement field, describe the global deformation of the laminate and appropriately obtained by employing an improved first-order shear deformation theory.For solving the coupled equilibrium equations of agenerally laminated composite plate, some of the stiffness... 

Nonlinear forced vibrations of thin functionally graded circular and elliptical plates under classical boundary conditions are investigated based on the classical plate theory. The von Kármán strain-displacement relations is employed to include geometrical nonlinearity caused by large transverse displacements of the plate thickness order, and modal expansion in polar and elliptical coordinate along with the perturbation method of multiple scale is used to solve the governing equations. The material properties are graded through the plate thickness according to a power-law distribution of the volume fraction of the constituents. Transverse forcing is supposed to be harmonic with angular... 

In the present research an analytical solution is studied for interlaminar stresses in boundary layer region of symmetric composite laminates under torsion. Based on geometrical and physical grounds the existing displacement field in literature is simplified in order to accommodate to torsion of symmetric laminates. Displacement field is divided to global and local parts. The solution procedure consists of combined equivalent single layer theories and layerwise theory of Reddy. ESL theories are more computationally economic while LWTs are considerably accurate in determining local behavior of plate. Further, based on second order shaer deformation theory and Ritz approximate variational... 

In the present study, analytical solutions within first-order shear deformation plate theory (FSDT), are presented for the linear and nonlinear asymmetric bending of functionally graded circular plates subjected to thermo-mechanical loading and boundary layer phenomenon is also investigated. To this end, cylindrical bending of long rectangular FG plates is also considered to study the perturbation technique which is used here to solve the nonlinear equations. Functionally graded materials are mostly used in high temperature environments and the study of their behavior under thermal and mechanical loadings and in small and large deflection ranges has become very important. Here, the linear... 

In the present study, an analytical solution is developed to calculate the interlaminar stresses in long symmetric laminated composite plates subjected to shearing load. At first, upon the successive integrations of the strain-displacement relations and using the existing patterns in deformation of a long symmetric laminate, the general displacement field is extracted and simplified to the final form. Presented solution is based on a combined method containing the equivalent single-layer (ESL) theories beside the Reddy’s layerwise theory. In this method, the equivalent single-layer theories are utilized because of their simplicity and low computational efforts rather than the layerwise... 

In the present study, an analytical solution is developed to calculate the interlaminar stresses in long generally cross-ply laminated composite plates subjected to bending. At first, upon the integration of the strain-displacement relations and using the existing patterns in deformation of the long laminate, the general displacement field is extracted and simplified to the final form. Presented solution is based on a combined method containing the equivalent single-layer (ESL) theories beside the Reddy’s layerwise theory. In this method, the equivalent single-layer theories are utilized because of their simplicity and low computational efforts rather than the layerwise theory in evaluation... 

In this study, using Reddy's layer-wise theory, thermal and rotational inter-laminar stress distribution within cylindrical composite shells with different boundary conditions is analytically studied. Convergence of the layer-wise theory is also studied and the numbers of sub-layers are determined so that efficient and accurate results can be achieved by this method. In order to assess the validity of layer-wise theory, results of this method are compared with results obtained by elasticity theory, for two sets of boundary conditions. It is observed that depending on the shell layer stacking, loading and boundary condition type, each of inter-laminar stresses may be the critical stress... 

The purpose of this research is to provide an analytical solution using first order shear deformation theory for nonlinear bending of rectangular FG plate under mechanical and thermal loads with different boundary conditions. To achieve this goal, extended Kantorovich method have been used. This method has a high convergence rate and is more accurate than other approximate methods, such as the Ritz and Galerkin methods, because the partially differential equations are converted to ordinary differential equations. In order to solving nonlinear odes the perturbation method is used. Material of the plate is a mixture of ceramic and metal and is modeled as an isotropic and non-homogeneous...