Loading...
Search for:
first-order-shears
0.006 seconds
Total 54 records
Dynamic stability of functionally graded cantilever cylindrical shells under distributed axial follower forces
, Article Journal of Sound and Vibration ; Vol. 333, Issue. 3 , 3 February , 2014 , pp. 801-817 ; ISSN: 0022460X ; Kazemi, M. T ; Reddy, J. N ; Haddadpoud, H ; Mahmoudkhani, S ; Sharif University of Technology
Abstract
In this paper, flutter of functionally graded material (FGM) cylindrical shells under distributed axial follower forces is addressed. The first-order shear deformation theory is used to model the shell, and the material properties are assumed to be graded in the thickness direction according to a power law distribution using the properties of two base material phases. The solution is obtained by using the extended Galerkin's method, which accounts for the natural boundary conditions that are not satisfied by the assumed displacement functions. The effect of changing the concentrated (Beck's) follower force into the uniform (Leipholz's) and linear (Hauger's) distributed follower loads on the...
Free-edge stresses in general cross-ply laminates
, Article Scientia Iranica ; Vol. 21, issue. 2 , April , 2014 , p. 387-402 ; Sharif University of Technology
Abstract
Within elasticity theory, the reduced form of a displacement field is obtained for general cross-ply composite laminates subjected to a bending moment. The firstorder shear deformation theory of plates and Reddy's layerwise theory are then utilized to determine the global deformation parameters and the local deformation parameters appearing in the displacement fields, respectively. For a special set of boundary conditions an elasticity solution is developed to verify the validity and accuracy of the layerwise theory. Finally, various numerical results are presented within the layerwise theory for edge-effect problems of several cross-ply laminates under the bending moment. The results...
Dynamic stability of cantilevered functionally graded cylindrical shells under axial follower forces
, Article Thin-Walled Structures ; Vol. 79, issue , June , 2014 , p. 138-146 ; Kazemi, M. T ; Haddadpour, H ; Mahmoudkhani, S ; Sharif University of Technology
Abstract
Flutter of cantilevered, functionally graded cylindrical shells under an end axial follower force is addressed. The material properties are assumed to be graded along the thickness direction according to a simple power law. Using the Hamilton principle, the governing equations of motion are derived based on the first-order shear deformation theory. The stability analysis is carried out using the extended Galerkin method and minimum flutter loads and corresponding circumferential mode numbers are obtained for different volume fractions, length-to-radius, and thicknesses-to-radius ratios. Two different configurations are considered for the FGM: one in which the metal phase is the outer layer...
Bending analysis of moderately thick functionally graded conical panels with various boundary conditions using GDQ method
, Article Composite Structures ; Volume 103 , September , 2013 , Pages 68-74 ; 02638223 (ISSN) ; Shakouri, M ; Kouchakzadeh, M. A ; Sharif University of Technology
2013
Abstract
This study presents the bending analysis of functionally graded conical panels under transverse compression with various boundary conditions. Equations was derived using first order shear deformation theory (FSDT) and solved using generalized differential quadrature (GDQ) method. Using this method results in the capability of studying any combinations of boundary conditions on four edges of the panel. Results are compared and validated with the results available in the literature. Effect of boundary conditions, volume fractions, panel length, semi-vertex angle and subtended angle on deflection of the panel was investigated
Effect of liquid viscosity on instability of high-spinning partially-filled shell rotors
, Article International Journal of Structural Stability and Dynamics ; Volume 13, Issue 6 , 2013 ; 02194554 (ISSN) ; Permoon, M. R ; Sharif University of Technology
2013
Abstract
In this study, the instability of spinning cylindrical shells partially filled with viscous liquid is investigated. Based on the Navier-Stokes equations for the incompressible flow, a 2D model is developed for liquid motion at each section of the cylinder. The governing equations of the cylinder vibrations are obtained based on the first-order shear deformable shell theory. The nonpenetration and no-slip boundary conditions of the flow on the wetted surface of the cylinder relate the liquid motion to the shell vibrations. Also the liquid pressure exerted on the cylinder wall combines the vibrations of the rotary cylinder to the liquid motion. By using the obtained coupled liquid-structure...
Dynamic response of a delaminated composite beam with general lay-ups based on the first-order shear deformation theory
, Article Composites Part B: Engineering ; Volume 55 , 2013 , Pages 65-78 ; 13598368 (ISSN) ; Kargarnovin, M. H ; Ahmadian, M. T ; Sharif University of Technology
2013
Abstract
The dynamic response analysis of a delaminated composite beam with a general lay-up traversed under an arbitrary moving/non-moving force is presented. By employing the energy method and introducing a new finite element, the global mass and stiffness matrices for a Laminated Composite Beam (LCB) of Timoshenko type are derived in which the material couplings (bending-tension, bending-twist, and tension-twist couplings) with the Poisson's effect are considered. In deriving the governing equation the non-penetration condition is imposed by employing the method of Lagrange multipliers. Out of a self-developed finite element program, the natural frequencies and time response of such LCB are...
Flutter of functionally graded open conical shell panels subjected to supersonic air flow
, Article Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering ; Volume 227, Issue 6 , 2013 , Pages 1036-1052 ; 09544100 (ISSN) ; Shokrollahi, H ; Sharif University of Technology
2013
Abstract
In this article, analysis of supersonic flutter of functionally graded open conical shell panels with clamped and simply supported edges is presented. The aeroelastic stability problem is formulated based on first-order shear deformation theory as well as classical shell theory and solved using Galerkin method. The effects of the volume fractions of constituent materials, the semi-vertex and subtended angles, thickness, and length on the flutter of the functionally graded conical shell panel are investigated. It is shown that the discrepancies between the results of the present classical shell theory and first-order shear deformation theory for the critical aerodynamic pressure are generally...
Free vibration analysis of moderately thick trapezoidal symmetrically laminated plates with various combinations of boundary conditions
, Article European Journal of Mechanics, A/Solids ; Volume 36 , 2012 , Pages 204-212 ; 09977538 (ISSN) ; Fallah, A ; Aghdam, M. M ; Sharif University of Technology
2012
Abstract
In this study, free vibration analysis of moderately thick symmetrically laminated general trapezoidal plates with various combinations of boundary conditions is investigated. The governing partial differential equations and boundary conditions for trapezoidal plate are obtained using first order shear deformation theory (FSDT) together with proper transformation from Cartesian system into trapezoidal coordinates. Generalized differential quadrature (GDQ) method is then employed to obtain solutions for the governing equations. Results of the GDQ method are compared and validated with available results in the literature which show accuracy and fast rate of convergence of the method. Effect of...
Free-edge stress analysis of general composite laminates under extension, torsion and bending
, Article Applied Mathematical Modelling ; Volume 36, Issue 4 , 2012 , Pages 1570-1588 ; 0307904X (ISSN) ; Sarvestani, M. Y ; Sharif University of Technology
2012
Abstract
In this study, based on the reduced form of elasticity displacement field for a long laminate, an analytical method is established to exactly obtain the interlaminar stresses near the free edges of generally laminated composite plates subjects to extension, torsion, and bending. The constant parameters being in the displacement field, which describe the global deformation of a laminate, are appropriately calculated by using the improved first-order shear deformation theory. Reddy's layerwise theory is subsequently employed for analytical and numerical examinations of the boundary layer stresses within arbitrary laminated composite plates. Various numerical results are developed for the...
Free vibration analysis of multilayered composite cylinder consisting fibers with variable volume fraction
, Article Composite Structures ; Volume 94, Issue 3 , 2012 , Pages 931-944 ; 02638223 (ISSN) ; Hashemi, M ; Sharif University of Technology
Abstract
In this paper, free vibration of a fiber reinforced composite cylinder in which volume fraction of its fibers vary longitudinally, is studied using a semi-analytical method. The distribution of volume fraction of fiber in base matrix is based on power law model. A micromechanical model is employed to represent its mechanical properties including elastic and physical properties of this composite cylinder. In addition, kinematically the first order shear deformation shell theory is employed for strain field. Then, weak form formulation and spatial approximations of variables are utilized to discretize the equations of motion. Different problems are solved in which primarily the validity of the...
Interlaminar stress analysis of general composite laminates
, Article International Journal of Mechanical Sciences ; Volume 53, Issue 11 , 2011 , Pages 958-967 ; 00207403 (ISSN) ; Yazdani Sarvestani, M ; Sharif University of Technology
Abstract
In this study, based on the reduced from of elasticity displacement field for a long laminate, an analytical method is established to exactly obtain the interlaminar stresses near the free edges of generally laminated composite plates under the extension and bending. The constant parameters, which describe the global deformation of a laminate, are properly computed by means of the improved first-order shear deformation theory. Reddys layerwise theory is subsequently utilized for analytical and numerical examinations of the boundary layer stresses within arbitrary laminated composite plates. A variety of numerical results are obtained for the interlaminar normal and shear stresses along the...
Stress Analysis of in Cross-ply Laminates in Bending
, M.Sc. Thesis Sharif University of Technology ; Nosier, Asghar (Supervisor)
Abstract
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...
Stress Analysis in Symmetric Composite Laminates Subjected to Shearing Load
, M.Sc. Thesis Sharif University of Technology ; Nosier, Asghar (Supervisor)
Abstract
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...
Panel Flutter Analysis of Cylindrical Constrained Layer Damping (CLD) Panels
, M.Sc. Thesis Sharif University of Technology ; Haddadpour, Hassan (Supervisor)
Abstract
The purpose of this study is to analytically study the aeroelastic characteristics of the cylindrical shells fully treated with passive constrained layer damping (PCLD) to indicate the effects of various parameters on the behavior of such structures. Constraining the viscoelastic layers increases the amount of dissipated energy and the bending stiffness of the structure without considerable change of the weight.
A thin shell theory in conjunction with the Donell assumptions is employed for the shell and the constraining layer (CL) and the first order shear deformation theory (FSDT) is used for the viscoelastic layer to construct the model. The effects of rotary inertia and shear...
A thin shell theory in conjunction with the Donell assumptions is employed for the shell and the constraining layer (CL) and the first order shear deformation theory (FSDT) is used for the viscoelastic layer to construct the model. The effects of rotary inertia and shear...
Thermal buckling analysis of piezoelectric functionally graded plates with temperature-dependent properties
, Article Mechanics of Advanced Materials and Structures ; Volume 22, Issue 10 , Nov , 2015 , Pages 864-875 ; 15376494 (ISSN) ; Fereidoon, A ; Khaksari Nouri, M ; Mareishi, S ; Sharif University of Technology
Taylor and Francis Inc
2015
Abstract
In this study, the thermal buckling analysis of hybrid laminated plates made of two-layered functionally graded materials (FGMs) that are integrated with surface-bonded piezoelectric actuators referred to as (P/FGM)s are investigated. Material properties for both substrate FGM layers and piezoelectric layers are temperature-dependent. Uniform temperature rise as a thermal load and constant applied actuator voltage are considered for this analysis. By definition of four new analytic functions, the five coupled governing stability equations, which are derived based on the first-order shear deformation plate theory, are converted into fourth-order and second-order decoupled partial differential...
Contact time study of electrostatically actuated microsystems
, Article Scientia Iranica ; Volume 17, Issue 5 B , SEPTEMBER-OCTOBER , 2010 , Pages 348-357 ; 10263098 (ISSN) ; Rashidian, B ; Ahmadian, M. T ; Sharif University of Technology
2010
Abstract
This paper presents a model to analyze contact phenomenon in microsystems actuated by ramp voltages, which has applications in frequency sweeping. First-order shear deformation theory is used to model dynamical system using finite element method, while finite difference method is applied to model squeeze film damping. The model is validated by static pull-in results. The presented hybrid FEMFDM model is utilized to compute values of contact time and dynamic behavior. Considering this model, effects of different geometrical and mechanical parameters on contact time are studied. The influence of imposing the additional reverse voltage on dynamic characteristics of the system is also...
Dynamic analysis of laminated composite plates traversed by a moving mass based on a first-order theory
, Article Composite Structures ; Volume 92, Issue 8 , 2010 , Pages 1865-1876 ; 02638223 (ISSN) ; Asghari, M ; Sharif University of Technology
2010
Abstract
The dynamic response of angle-ply laminated composite plates traversed by a moving mass or a moving force is investigated. For this purpose, a finite element method based on the first-order shear deformation theory is used. Stationary and adaptive mesh techniques have been applied as two different meshing schemes. The adaptive mesh strategy is then used to avoid off-nodal position of moving mass. In this manner, the finite element mesh is continuously adapted to follow and comply with the path of moving mass. A Newmark direct integration method is employed to solve the equations of motion. Parametric study is directed to find out how different parameters like mass of the moving object as...
Contact time study of microsystems actuated by ramp-input voltages
, Article ASME 2009 International Mechanical Engineering Congress and Exposition, IMECE2009, Lake Buena Vista, FL, 13 November 2009 through 19 November 2009 ; Volume 12, Issue PART A , 2010 , Pages 105-112 ; 9780791843857 (ISBN) ; Rashidian, B ; Ahmadian, M. T ; Sharif University of Technology
American Society of Mechanical Engineers (ASME)
2010
Abstract
This paper presents a model to analyze contact phenomenon in microsystems, actuated by ramp voltages, which has applications in frequency sweeping. First-order shear deformation theory is used to model dynamical system using finite element method, while finite difference method is applied to model squeeze film damping. The model is validated by static pull-in results. The presented hybrid FEM-FDM model is utilized to compute values of contact time and dynamic behavior. Considering this model, effects of different geometrical and mechanical parameters on contact time are studied. The influence of imposing the additional reverse voltage on dynamic characteristics of the system is also...
Vibration behavior of laminated composite beams integrated with magnetorheological fluid layer
, Article Journal of Mechanics ; 2016 , Pages 1-9 ; 17277191 (ISSN) ; Zabihollah, A ; Behzad, M ; Sharif University of Technology
Cambridge University Press
Abstract
Vibration behavior of adaptive laminated composite beams integrated with magnetorheological (MR) fluid layer has been investigated using layerwise displacement theory. In most of the existing studies on the adaptive laminated beams with MR fluids, shear strain across the thickness of magnetorheological (MR) layer has been assumed a constant value, resulting in a constant shear stress in MR layer. However, due to the high shear deformation pattern inside MR layer, this assumption is not adequate to accurately describe the shear strain and stress in MR fluid layer. In this work a modified layerwise theory is employed to develop a Finite Element Model (FEM) formulation to simulate the laminated...
Natural frequency analysis of functionally graded material truncated conical shell with lengthwise material variation based on first-order shear deformation theory
, Article Mechanics of Advanced Materials and Structures ; Volume 23, Issue 5 , 2016 , Pages 565-577 ; 15376494 (ISSN) ; Kargarnovin, M. H ; Satouri, S ; Satouri, A ; Sharif University of Technology
Taylor and Francis Inc
2016
Abstract
Based on the first-order shear deformation theory, the free vibration of the functionally graded (FG) truncated conical shells is analyzed. The truncated conical shell materials are assumed to be isotropic and inhomogeneous in the longitudinal direction. The two-constituent FG shell consists of ceramic and metal. These constituents are graded through the length, from one end of the shell to the other end. Using Hamilton's principle the derived governing equations are solved using differential quadrature method. Fast rate of convergence of this method is tested and its advantages over other existing solver methods are observed. The primary results of this study were obtained for four...