Sharif Digital Repository

Magnetorheological (MR) materials show variations in their rheological properties when subjected to varying magnetic fields. They have quick time response, in the order of milliseconds, and thus are potentially applicable to structures and devices when a tunable system response is required. When integrated with a structural system, they can produce higher variations in the dynamic response of the structure. In this thesis, vibration behavior of laminated-composite beam with MR Fluid is investigated.In most studies, shear strain across the thickness of MR layer has been considered as a constant value which does not precisely describe the actual shear strain field. Shear modulus of MR layer in... 

Today, composites are widely used in various industries, thus the study and analysis of properties and their behaviors are very important. In addition, the use of multi-layered composites in the aerospace industry is important. The composite-elastomer structures, specially their spherical shape, are widely used as flexible joint in aerospace industries, such as the thrust vector control system in solid-propellant rockets and the helicopter industry. In this study, an analytical approach is proposed for calculating the interlaminar stresses of laminated plates and spherical shells with arbitrary laminations and boundary conditions based on a threedimensional multi-term extended Kantorovich... 

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... 

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... 

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...