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In this study, the deflection and stress field of perfect and imperfect (with and without porosities) functionally graded (FG) cylindrical panels are determined following the first-order shear deformation theory (FSDT). The panel rested on the twoparameter elastic foundation (Pasternak foundation) under pressure loads and worked in a hygro-thermal environment. Navier's solution has been used for simply supported cylindrical panels to analyze the effects of porosity, geometrical and foundation parameters, as well as temperature and humidity on deflection and stress field. The validated examples demonstrate the reliability of the solution and the self-written Matlab program. Numerical investigations show a significant hygro-thermal effect on the static response of the FG panel. [ABSTRACT FROM AUTHOR]

In the framework of 3D elasticity theory, the static behavior of functionally graded viscoelastic cylindrical panels with piezoelectric layers under electro-mechanical loads is investigated. The viscoelastic material is modeled using Boltzmann's integral model, and its Poisson's ratio is constant, and for its time-dependent Young's modulus, spatially, the power distribution in the radial direction is considered. Modulus time changes are also expressed using the Prony series. For simply supported edges, the state space method and Fourier expansion, and for other boundary conditions, the semi-analytical approach by the state space differential quadrature method (DQM) are used. Equations of motion are solved in the Laplace domain and by the Laplace inverse technique, results are transferred back to the time domain numerically. Also, the results of this research have been validated with other similar research. Finally, the effect of different parameters such as the type of supports, the relaxation time constant, thickness of the piezoelectric layer, and other important parameters on the static response of the panel have been investigated. Results demonstrate that if the ratio of the total layer thickness to the piezoelectric thickness exceeds a specified value, the effect of the thickness of the piezoelectric layer on mechanical behavior can be disregarded. Furthermore, when relaxation time constant increases, the amount of stress remains constant for a constant thickness and equals the amount of stress in the elastic panel. However, the amount of displacement decreases. [ABSTRACT FROM AUTHOR]

This paper develops a new structure dynamic model to investigate nonlinear transient responses of the rotating blade made of functionally graded material (FGM). The rotating blade is simplified as a rotating FGM cylindrical panel with a presetting angle and a twist angle. The geometric nonlinearity effects are taken into account in the strain-displacement relationships, which are derived by Green strain tensor. Based on the first-order piston theory and the first-order shear deformation theory, the equations of motion for the rotating twisted FGM cylindrical panel are acquired by means of Hamilton principle and Galerkin method. Backward Differentiation Formula (BDF) and Runge-Kutta Algorithm are used to solve the nonlinear equations of motion for the system. The effects of four pulse load conditions on the system subjected to the internal pulse load or the external pulse load are fully discussed. A detailed parametric analysis is performed by considering the effects of the rotating speed, volume fraction index and temperature. [ABSTRACT FROM AUTHOR]

In this paper, buckling analysis of cylindrical panels made of functionally graded material under the action of three types of thermal loads is investigated. At first, Governing equations of panels are obtained based on the second Piola-Kirchhoff stress tensor using three dimensional theory of elasticity. Stability equations of the shells subjected to thermal loading based on the Donnell shell theory are considered. Two methods of solution are employed. In the first method governing equations obtained by benchmark solution are discretized and solved using differential quadrature method. Then the closed form solution is presented for the buckling equations based on the Donnell shell theory. It is assumed that material properties of the shell vary continually through the thickness according to a power law distribution of the volume fraction of constituent materials, while the Poissonâs ratio is constant. The effects of various parameters including the power law exponent, panel angle, different thermal load conditions and geometric ratios on the buckling behavior of functionally graded cylindrical panels are studied.

Abstract The aim of this study is to give a numerical solution for free vibration problem of functionally graded and carbon nanotube reinforced (CNTR) circular cylindrical panel. Based on the Love’s shell theory and first-order shear deformation theory (FSDT), related equations of motion have been obtained. Then, the methods of harmonic differential quadrature (HDQ) and discrete singular convolution (DSC) are used for numerical computations. Two different material properties are assumed to change continuously in the thickness direction according to the volume fraction power law and the general four-parameter power law distributions. Accuracy and convergence of the methods have been validated by comparing the obtained results with the existing results available in the open literature. Frequency values have been given for different material and geometric parameters, modes and boundary cases for circular cylindrical panels with FGM and CNTR cases. The effects of types of distributions of CNTR material are also discussed. [ABSTRACT FROM AUTHOR]

Present research deals with the geometrically nonlinear bending of a long cylindrical panel made of a through-the-thickness functionally graded material subjected to thermal load. A panel under the action of uniform temperature rise loading is considered. Formulation of the shell is based on the third-order shear deformation shell theory, where the first-order shear deformation and classical shell theory may be extracted as special cases. Thermomechanical properties of the shell are assumed to be temperature dependent and are estimated according to a power law function across the shell thickness. Also, it is assumed that shell is in contact with an elastic foundation which acts in tension as well as in compression. The nonlinear governing equations of the shell are obtained using the von Kármán type of geometrical nonlinearity. The obtained governing equations are solved for two cases, i.e., simply supported shells and clamped shells. The developed equations are solved using a two-step perturbation technique. Accurate closed-form expressions are provided to obtain the mid-span deflection of the shell as a function of temperature elevation. Numerical results are provided to analyze the effects of power law exponent, boundary conditions, temperature dependency, side to radius ratio, and side to thickness ratio. [ABSTRACT FROM AUTHOR]

Mechanical behavior of a viscoelastic cylindrical panel with various edge boundary conditions, made up of functionally graded material (FGM) and subjected to thermal or mechanical load is investigated. For cases of simply supported boundary conditions, analytical solution is presented through Fourier series expansion along the axial and circumferential coordinates as well as state space method along the radial coordinate. For nonsimply supported conditions, semi-analytical solution is performed using differential quadrature method instead of Fourier series solution. Governing differential equations are transformed to Laplace transform domain and using inverse Laplace transform, obtained solutions are converted to time domain. In the present work, relaxation modulus of FGM is supposed to be according to the Prony series with power law variations along the radial direction. Numerical comparison was made with the available published results to assess the validity of present technique. Effect of relaxation time constant, thickness to mid-radius ratio, edges boundary condition and outer surface temperature on stress and displacement fields are discussed. Besides, time history of stresses for different relaxation time constant and for various boundary conditions is presented. [ABSTRACT FROM AUTHOR]

A cylindrically curved panel in a state of generalized plane strain subject to a radial temperature gradient is discussed by analytical means. The ends of this thick-walled shell are presupposed to be guided in such a way that a displacement in circumferential direction may occur and that the radius of the middle surface remains unchanged. Then, couples act on those ends, giving rise to pure bending condition. The material is power-law functionally graded, and - based on the rule of mixtures - a coherent dependence of all the material properties (except for Poisson's ratio) on the radial coordinate is taken into account. The stresses occurring for both a positive and a negative temperature gradient are analyzed, and one finds that, depending on the grading exponent, the yield limit according to von Mises may be reached either at the inner surface, the outer surface or at both surfaces simultaneously. Numerical results are provided for a steel/aluminum FGM, and it is shown that by appropriate grading not only a reduction of the couples acting at the supports but in some cases also a considerable reduction of the weight of the panel may be achieved. [ABSTRACT FROM AUTHOR]

In this study, the magnetic-mechanical buckling of a cylindrical panel made of two-dimensional functionally graded materials (2D-FGMs) has been investigated. The panel contains longitudinal and circumferential stiffeners and has been subjected to a uniform magnetic field as well as axial load. Material properties of the cylindrical panel are assumed to vary continuously in radial and thickness directions as a function of the volume fraction of the components. The magnetic field has been exerted radially. Equilibrium and stability equations have been derived using both Hamilton's principle and principle of minimum potential energy based on the third-order shear deformation theory (TSDT). The generalized differential quadrature method (GDQ) has been employed to solve the coupled differential equations. Moreover, the effect of geometry, load, magnitude of the magnetic field, number of stiffeners, and volume fraction coefficient on the critical buckling load has been determined. The results are in good agreement with the previous related works. [ABSTRACT FROM PUBLISHER]

A three-dimensional piezoelasticity analysis is presented for a functionally graded circular cylindrical panel with piezoelectric fiber composite layers as sensor and actuator under dynamic load and electrical excitation. It is assumed that the material properties of functionally graded material obey the power law. Moreover, the effective properties of the piezoelectric composite layers are derived from the properties of their constituents using iso-field assumption. Three-dimensional finite element analysis is applied to solve the coupled partial differential equations (PDEs), including Maxwell’s equation for electric displacement and three equations of motion. Discretized governing equations are solved over time domain using Houbolt time integration scheme. The stress and potential electricity results are compared for various supports, electrical excitation voltages, and volume fractions. Moreover, the results are provided versus time domain and a comparison has been made between sensor voltage and the corresponding stress component. [ABSTRACT FROM AUTHOR]

Polymeric foams are new materials which prefer special mechanical and thermal properties for mechanical designers. The best mathematical model for polymeric and metallic foams is functionally graded viscoelastic (FGV) materials. So, this paper has concentrated on presenting a reliable and accurate method for free vibration of FGV panels. For this purpose, Levy-type circular cylindrical panel consisting of FGV material is modeled based on Sanders first order shear deformation type theory, as geometrical model, and linear Zener model with variable properties through the thickness, as the best constitutive relation for FGV materials. Validity and accuracy of present method are approved by comparing it with finite element in different tables. Also, effects of various geometrical and material parameters on natural frequencies and decay rate are studied. [ABSTRACT FROM AUTHOR]

Abstract: This work deals with a study of the vibrational properties of functionally graded nanocomposite cylindrical panels reinforced by single-walled carbon nanotubes (SWCNTs) based on the three-dimensional theory of elasticity. The carbon nanotube reinforced (CNTRC) cylindrical panel have smooth variation of carbon nanotube (CNT) fraction in the radial direction and the material properties are estimated by the extended rule of mixture. Symmetric and asymmetric volume fraction profiles are provided in this paper for comparison. Suitable displacement functions that identically satisfy the boundary conditions at the simply supported edges are used to reduce the equilibrium equations to a set of coupled ordinary differential equation with variable coefficients, which can be solved by a generalized differential quadrature (GDQ) method. The results show that the kind of distribution and volume fraction of CNT have a significant effect on normalized natural frequency. [Copyright &y& Elsevier]

The transient heat conduction in a functionally graded cylindrical panel is investigated based on the dual phase lag (DPL) theory in this article. Except for the phase lags which are assumed to be constant, all the other material properties of the panel are assumed to change continuously along the radial direction according to a power-law formulation with different non-homogeneity indices. The heat conduction equations based on the DPL theory in the cylindrical coordinate system are written in a general form which are then used for the analyses of four different geometries: (1) a hollow cylinder of an infinite length; (2) a hollow cylinder of a finite length; (3) a cylindrical panel of an infinite length; and (4) a cylindrical panel of a finite length. Using the Laplace transform, the analytical solutions for temperature and heat flux are obtained in the Laplace domain. The solutions are then converted into the time domain by employing the fast Laplace inversion technique. The exact expressions for the radial thermal wave speed are obtained for the four different geometries. The numerical results are displayed to reveal the effect of different approximations of the DPL theory on the temperature distribution for various non-homogeneity indices. The results are verified with those reported in the literature. [ABSTRACT FROM AUTHOR]

Abstract: A general method is presented for the analysis of a thermoelastic multi-layered cylindrical panel made of an oblique pile of functionally graded layers having orthotropic material properties. The two edges of the panel are under simply-supported and zero temperature conditions. Steady-state thermal and mechanical boundary conditions can be applied on the innermost and outermost surfaces of the cylindrical panel. In addition, the functionally graded material is assumed to be of a power law type in the radial direction and the homogeneous solution in each layer is obtained in terms of the pseudo-Stroh formalism. The solution for the multi-layered cylindrical panel is derived based on the transfer matrix method. Novel to this work, is an alternative but equivalent formulation for the transfer matrix method which is more concise in expression. The derived solution is subsequently applied to investigate a five-layered cylindrical panel. The influence of the gradation of the material and ply angle on the distribution of temperature, displacements and stresses are investigated. The results clearly show that material gradation and ply angle significantly influence the elastic fields and temperature. [Copyright &y& Elsevier]

This article is concerned with the theoretical treatment of transient thermoelastic problem involving a functionally graded cylindrical panel due to nonuniform heat supply in the circumferential direction. The thermal and thermoelastic constants of the cylindrical panel are expressed as power functions of the radial coordinate variable. The exact solution for the two-dimensional temperature change in a transient state, and thermal stresses of a simple supported cylindrical panel under the state of plane strain is obtained herein. Some numerical results are shown in figures. Furthermore, the influence of the nonhomogeneity of the material upon the temperature change, displacements, and stresses is investigated. [ABSTRACT FROM AUTHOR]

Abstract: Three-dimensional thermo-elastic analysis of a functionally graded cylindrical panel with finite length and subjected to nonuniform mechanical and steady-state thermal loads are carried out in this paper. Thermal and mechanical properties of the functionally graded material are assumed to be temperature independent and continuously vary in the radial direction of the panel. Analytical solutions for the temperature and stress fields expressed in terms of trigonometric and power series for the simply supported boundary conditions are derived and graphically presented. [Copyright &y& Elsevier]

Abstract: This paper is concerned with the theoretical treatment of the steady-state thermoelastic problem of a functionally graded cylindrical panel due to nonuniform heat supply in the circumferential direction. The thermal and thermoelastic constants of the cylindrical panel are expressed as power functions of the radial coordinate. We obtain the exact solution for the two-dimensional temperature change in a steady state, and thermal stresses of a simple supported cylindrical panel under the state of plane strain. Some numerical results are shown in figures and tables. Furthermore, the influence of the nonhomogeneity of the material, the radius ratio and the span angle upon the temperature change, displacements and stresses is investigated. [Copyright &y& Elsevier]