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Free and forced random vibration analysis of sandwich plates with thick viscoelastic cores
, Article JVC/Journal of Vibration and Control ; Volume 19, Issue 14 , 2013 , Pages 2223-2240 ; 10775463 (ISSN) ; Haddadpour, H ; Navazi, H. M ; Sharif University of Technology
2013
Abstract
Free vibrations and the transverse response of sandwich plates with viscoelastic cores under wide-band random excitation is studied with special attention to the so-called pumping, thickness-shear and stretching modes. The quadratic displacement field is adopted for all displacement components of the core to accurately capture the higher modes excited by the wide-band excitation. The Love-Kirchhoff plate theory is used for the face layers. The viscoelastic behavior of the core is modeled by the Golla-Hughes-McTavish method. An analytical solution using the normal mode method is provided for the simply supported boundary conditions by including a different family of modes. The effects of some...
The effects of nonlinearities on the vibration of viscoelastic sandwich plates
, Article International Journal of Non-Linear Mechanics ; Vol. 62 , 2014 , Pages 41-57 ; ISSN: 00207462 ; Haddadpour, H ; Navazi, H. M ; Sharif University of Technology
Abstract
The nonlinear free and forced bending vibration of sandwich plates with incompressible viscoelastic core is investigated under the effects of different source of nonlinearities. For the core constrained between stiffer layers, the transverse shear strains, as well as the rotations are assumed to be moderate. The linear and quadratic displacement fields are also adopted for the in-plane and out-of-plane displacements of the core, respectively. The assumption of moderate transverse strains requires a nonlinear constitutive equation which is obtained from a single-integral nonlinear viscoelastic model using the assumed order of magnitudes for linear strains and rotations. The 5th-order method...
Vibration Analysis of viscoelastic Sandwich Plates Under the Effects of Nonlinearities and Random Excitations
, Ph.D. Dissertation Sharif University of Technology ; Haddadpour, Hassan (Supervisor)
Abstract
Different aspects of oscillatory behaviors of sandwich structures with viscoelastic cores are investigated in the present study in four parts. In the first part, an analytical study is conducted to determine the variation of linear frequencies and damping ratio of different families of modes with system parameters. The participation of different families of modes such as the so-called pumping or thickness-shear modes along with the overall bending modes in the transverse response of the structure to transverse wide-band excitation is also investigated in this part. The formulation of the problem is established by assuming quadratic variation of displacement components of the core through the...
Dynamic Response Analysis of a Three-Layered Circular Plate with Magnetorheological Fluid Core Under Low Velocity Impact Loading
, M.Sc. Thesis Sharif University of Technology ; Haddadpour, Hassan (Supervisor)
Abstract
Various public transportation types, e.g., Trains, Buses, and Airplanes, are susceptible to damages made by the impacts of the external objects, which are typically classified as low to medium velocity impacts. This problem reveals the significance of investigating the effects of impact on thin-walled structures, which are the main components of these vehicles' bodies. Owing to the controllable rheological properties of the Magnetorheological fluid with respect to the magnetic field, it can be utilized to control the structure exposed to impact adaptively and minimize the damages. Due to this purpose, sandwich structures such as sandwich beams and plates, thanks to their extended response...
Linear and Nonlinear Bending Analysis of Circular Sandwich Plates with FG Porous Core Reinforced with Graphene Nanoplatelets
, M.Sc. Thesis Sharif University of Technology ; Fallah Rajabzadeh, Famida (Supervisor)
Abstract
In this study non-linear bending of circular sandwich plates with functionally graded (FG) porous core reinforced with graphene nanoplatelets (GPL) is investigated using refined shear deformation theory (RSDT). Displacement field of this theory is considered so that different theories can be introduced to estimate transverse shear strain. Equilibrium equations and boundary conditions are derived using minimum total potential energy principle. The equations are reformulated using potential and stress functions and analytical solution is obtained using perturbation method along with Fourier series. Validations are performed for two cases of linear and non-linear bending of circular plate and...
Non-Linear Aeroelastic Analysis of Three-Layered Plates with Magneto-Rheological Fluid Core in Supersonic Airflow
, M.Sc. Thesis Sharif University of Technology ; Haddadpour, Hassan (Supervisor)
Abstract
This study is a comprehensive analysis on the nonlinear vibration of a sandwich plate containing magnetorheological (MR) fluid as the core layer. The nonlinear aeroelastic analysis of the structure is also discussed to determine the flutter boundaries. In this study, the numerical Generalized Differential Quadrature (GDQ) method is applied to investigate the free vibration analysis of a sandwich plate with a MR fluid core. The classical thin plate theory (CPT) and the First-order Shear Deformation Theory (FSDT) are assumed for face layers and core layer, respectively. These theories along with Von-Karman kinematic formulations are incorporated to extract governing equations. The equations of...
Analytical non-linear analysis of functionally graded sandwich solid/annular sector plates
, Article Composite Structures ; Volume 275 , 2021 ; 02638223 (ISSN) ; Fallah, F ; Sharif University of Technology
Elsevier Ltd
2021
Abstract
Nonlinear behavior of functionally graded (FG) sandwich circular sector plates with simply supported radial edges under transverse loading is investigated using the first-order shear deformation theory with von Karman geometric nonlinearity. The nonlinear governing equations are reformulated and solved via single-parameter perturbation and Fourier series methods. Verification is performed by comparing numerical results with the available ones in the literature and the ones obtained via ABAQUS code. The effects of non-linearity, material constant, lay-up, and boundary conditions on bending of FG sandwich sector plates with FG core/homogenous face sheets and metallic core/FG face sheets are...