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Response and Deflection Investigation of FGM Plates Under Thermo-mechanical Loads
, M.Sc. Thesis Sharif University of Technology ; Abedian, Ali (Supervisor)
Abstract
In the aerospace industry, there are a lot of high temperature environments, including engine parts and heat shields, in which the damages under these working conditions may be so destructive and even in some cases; they may result in sudden catastrophic failure of the structure. Nowadays, to prevent the occurrence of such failures and to provide the appropriate materials capable of working in such harsh environments and being able to protect the other adjacent structural components, new generation of thermal barrier coating materials so called Functionally Graded Materials (FGMs), with the controllable material properties in one or more directions were introduced. Recently, FGM applications...
An analytical model for stress analysis of short fiber composites in power law creep matrix
, Article International Journal of Non-Linear Mechanics ; Volume 57 , 2013 , Pages 39-49 ; 00207462 (ISSN) ; Abedian, A ; Sharif University of Technology
2013
Abstract
The creep deformation behavior of short fiber composites has been studied by an approximate analytical model. A perfect fiber/matrix interfacial bond is assumed and a power law function is considered for describing the steady state creep behavior of the matrix material. The results obtained from the proposed analytical solution satisfy the equilibrium and constitutive creep equations. Also, a parametric study was undertaken to define the effects of geometric parameters on the steady state creep strain rate of short fiber composites. The present model is then validated using the results of finite element method. The predicted strain rate and stress components by the proposed analytical...
Dynamic analysis of three-layer cylindrical shells with fractional viscoelastic core and functionally graded face layers
, Article JVC/Journal of Vibration and Control ; Volume 27, Issue 23-24 , 2021 , Pages 2738-2753 ; 10775463 (ISSN) ; Permoon, M. R ; Askarian, A ; Haddadpour, H ; Sharif University of Technology
SAGE Publications Inc
2021
Abstract
Natural frequency and damping behavior of three-layer cylindrical shells with a viscoelastic core layer and functionally graded face layers are studied in this article. Using functionally graded face layers can reduce the stress discontinuity in the face–core interface that causes a catastrophic failure in sandwich structures. The viscoelastic layer is expressed using a fractional-order model, and the functionally graded layers are defined by a power law function. Assuming the classical shell theory for functionally graded layers and the first-order shear deformation theory for the viscoelastic core, equations of motion are derived using Lagrange’s equation and then solved via Rayleigh–Ritz...
A novel phenomenological constitutive model for Ti-6Al-4V at high temperature conditions and quasi-static strain rates
, Article Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering ; Volume 235, Issue 13 , 2021 , Pages 1831-1842 ; 09544100 (ISSN) ; Hosseini Kordkheili, A ; Sharif University of Technology
SAGE Publications Ltd
2021
Abstract
Phenomenological constitutive modeling of Ti-6Al-4V at temperatures between 923 and 1023 K under 0.0005–0.05 s−1 quasi-static rates is studied based on a phenomenological approach. For this purpose, the Johnson–Cook constitutive model is revisited. At low temperature conditions under moderate to high strain rates, the material’s stress–strain curves are the most similar to power-law function. Contrary to this, at high temperature conditions under low to moderate strain rates, the saturation-type function well describes the stress–strain curves. On the other hand, it is illustrated that the Johnson–Cook constitutive model is feeble to predict the material’s behavior correctly. Accordingly, in...
Nonlinear analysis of FGM plates under pressure loads using the higher-order shear deformation theories
, Article Composite Structures ; Volume 89, Issue 3 , 2009 , Pages 333-344 ; 02638223 (ISSN) ; DehghanManshadi, B ; Abedian, A ; Sharif University of Technology
2009
Abstract
In this study, the energy concept along with the first- and third-order shear deformation theories (FSDT and TSDT) are used to predict the large deflection and through the thickness stress of FGM plates. These responses are studied and discussed as a function of plate thickness and the order "n" of a power law function which is considered for the through the thickness variation of the properties of the FGM plate. The results show that the energy method powered by the FSDT and FSDT is capable of predicting the effects of plate thickness on the deformation and the through the thickness stress. Here, also the effects of power "n" on the plate response is clearly depicted. Notably, the...
Dynamic analysis of three-layer cylindrical shells with fractional viscoelastic core and functionally graded face layers
, Article JVC/Journal of Vibration and Control ; 2020 ; Permoon, M. R ; Askarian, A ; Haddadpour, H ; Sharif University of Technology
SAGE Publications Inc
2020
Abstract
Natural frequency and damping behavior of three-layer cylindrical shells with a viscoelastic core layer and functionally graded face layers are studied in this article. Using functionally graded face layers can reduce the stress discontinuity in the face–core interface that causes a catastrophic failure in sandwich structures. The viscoelastic layer is expressed using a fractional-order model, and the functionally graded layers are defined by a power law function. Assuming the classical shell theory for functionally graded layers and the first-order shear deformation theory for the viscoelastic core, equations of motion are derived using Lagrange’s equation and then solved via Rayleigh–Ritz...
A spectral theory formulation for elastostatics by means of tensor spherical harmonics
, Article Journal of Elasticity ; Volume 111, Issue 1 , 2013 , Pages 67-89 ; 03743535 (ISSN) ; Shodja, H. M ; Sharif University of Technology
2013
Abstract
Consider a set of (N+1)-phase concentric spherical ensemble consisting of a core region encased by a sequence of nested spherical layers. Each phase is spherically isotropic and is functionally graded (FG) in the radial direction. Determination of the elastic fields when the outermost spherical surface is subjected to a nonuniform loading and the constituent phases are subjected to some prescribed nonuniform body force and eigenstrain fields is of interest. When the outermost layer is an unbounded medium with zero eigenstrain and body force fields, then an N-phase multi-inhomogeneous inclusion problem is realized. Based on higher-order spherical harmonics, presenting a three-dimensional...
Temperature and thickness effects on thermal and mechanical stresses of rotating FG-disks
, Article Journal of Mechanical Science and Technology ; Volume 25, Issue 3 , 2011 , Pages 827-836 ; 1738494X (ISSN) ; Azadi, M ; Sharif University of Technology
Abstract
In the present paper, radial and hoop thermal and mechanical stress analysis of a rotating disk made of functionally graded material (FGM) with variable thickness is carried out by using finite element method (FEM). To model the disk by FEM, one-dimensional two-degree elements with three nodes are used. It is assumed that the material properties, such as elastic modulus, Poisson's ratio and thermal expansion coefficient, are considered to vary using a power law function in the radial direction. The geometrical and boundary conditions are in the shape of two models including thermal stress (model-A) and mechanical stress (model-B). In model-A there exists no pressure in both external and...
Supersonic flutter prediction of functionally graded conical shells
, Article Composite Structures ; Volume 92, Issue 2 , 2010 , Pages 377-386 ; 02638223 (ISSN) ; Haddadpour, H ; Navazi, H.M ; Sharif University of Technology
2010
Abstract
Aero-thermoelastic analysis of a simply supported functionally graded truncated conical shell subjected to supersonic air flow is performed to predict the flutter boundaries. The temperature-dependent properties of the FG shell are assumed to be graded through the thickness according to a simple rule of mixture and power-law function of volume fractions of material constituents. Through the thickness steady-state heat conduction is considered for thermal analysis. To perform the stability analysis, the general nonlinear equations of motion are first derived using the classical Love's shell theory and the von Karman-Donnell-type of kinematic nonlinearity together with the linearized...