Showing papers on "Functionally graded material published in 2007"
TL;DR: In this article, a tensor-based finite element formulation with curvilinear coordinates and first-order shear deformation theory is used to develop the functionally graded shell finite element.
190 citations
TL;DR: In this article, a functionally graded structure for hollow particle (microballoon) filled syntactic foams is fabricated that is capable of withstanding compression for 60-75% strain without any significant loss in strength.
185 citations
TL;DR: In this paper, the coupled thermo-mechanical and energy equations for a functionally graded axisymmetric cylindrical shell subjected to thermal shock load were simultaneously solved for a functional graded axismmetric shell.
116 citations
TL;DR: In this paper, a piecewise-exponential model (PE model) is developed to investigate the crack problem of the functionally graded materials (FGMs) with arbitrary properties, where the real material properties can be approached by a series of exponential functions.
113 citations
TL;DR: In this article, the authors considered the plane stress problem of generally anisotropic beams with elastic compliance parameters being arbitrary functions of the thickness coordinate and developed a unified method to obtain the stress function.
111 citations
TL;DR: In this article, a postbuckling analysis for a functionally graded cylindrical shell with piezoelectric actuators subjected to lateral or hydrostatic pressure combined with electric loads in thermal environments is presented.
110 citations
TL;DR: In this paper, two different kinds of heterogeneous elastic hollow cylinders are studied, one is a cylinder with multi-layer and another is a cylindrical cylinder with continuously graded properties.
105 citations
TL;DR: In this article, an approach for fabricating functionally graded specimens of supernickel alloy and ceramic compositions via Selective Laser Melting (SLM) is presented, aimed at using the functionally graded material (FGM) concept to gradually grade powdered compositions of Zirconia within a base material of Waspaloy®.
Abstract: An approach for fabricating functionally graded specimens of supernickel alloy and ceramic compositions via Selective Laser Melting (SLM) is presented. The focus aimed at using the functionally graded material (FGM) concept to gradually grade powdered compositions of Zirconia within a base material of Waspaloy®. A high power Nd:YAG laser was used to process the material compositions to a high density with gradual but discrete changes between layered compositions. The graded specimens initially consisted of 100% Waspaloy® with subsequent layers containing increased volume compositions of Zirconia (0–10%). Specimens were examined for porosity and microstructure. It was found that specimens contained an average porosity of 0.34% with a gradual change between layers without any major interface defects.
104 citations
TL;DR: In this article, transient heat conduction in a cylindrical shell of functionally graded material is studied by using analytical method, the shell is assumed to be in axisymmetry conditions and the material properties are considered to be nonlinear with a power law distribution through the thickness.
Abstract: In this article, transient heat conduction in a cylindrical shell of functionally graded material is studied by using analytical method. The shell is assumed to be in axisymmetry conditions. The material properties are considered to be nonlinear with a power law distribution through the thickness. The temperature distribution is derived analytically by using the Bessel functions. To verify the proposed method the obtained numerical results are compared with the published results. The comparisons of temperature distribution between various time and material properties are presented.
102 citations
TL;DR: In this paper, a nonlinear thermomechanical post-buckling of an imperfect functionally graded material (FGM) circular plate, subjected to both mechanical load and transversely non-uniform temperature rise, is presented.
Abstract: Nonlinear thermomechanical post-buckling of an imperfect functionally graded material (FGM) circular plate, subjected to both mechanical load and transversely non-uniform temperature rise, is presented. The material properties of FGM plates are assumed to be graded in the thickness direction according to a simple power law distribution in terms of the volume fractions of the constituents. Based on von Karman's plate theory, equilibrium equations governing a large axi-symmetric deformation of the FGM circular plate under thermomechanical loads are derived. In the analysis, the geometric imperfections of the plate are taken into account. By using a shooting method the nonlinear ordinary differential equations with immovably clamped boundary conditions are solved numerically. Responses for the nonlinear thermomechanical post-buckling responses of the FGM plate are obtained. Numerical examples are presented that relate to the performances of perfect and imperfect, homogenous and graded plates. Characteristic curves of the post-buckling deformation of the imperfect FGM circular plate varying with thermal loads, imperfection parameters and volume fraction index are plotted. And then effects of the load parameters, materials constitution, and the geometric imperfection of the plate on the deformation are discussed in detail.
95 citations
TL;DR: In this paper, the theoretical treatment of transient thermoelastic problem involving an orthotropic functionally graded rectangular plate due to non-uniform heat supply was studied. But the authors only considered the case of a simple supported rectangular plate and did not consider the nonhomogeneity and orthotropy of the material.
TL;DR: The modified smoothed particle hydrodynamics (MSPH) method is used to study the propagation of elastic waves in functionally graded materials and it is shown that, for the same placement of particles/nodes the MSPH method gives better results than the finite element method.
TL;DR: In this article, the propagation behavior of transverse surface waves (love waves) in a piezoelectric half space of polarized ceramics carrying a functionally graded material layer is studied from the three-dimensional equations of linear piezolectricity, and the effect of gradient coefficients on the dispersive relations and phase velocities of Love wave propagation is discussed in detail.
TL;DR: In this article, the authors investigated the dynamic stability of thick functionally graded material plates subjected to aero-thermo-mechanical loads, using a novel numerical solution technique, the moving least squares differential quadrature method.
TL;DR: In this paper, the thermal buckling loads of truncated conical shells of functionally graded material are considered, where the material properties of the shells are assumed to vary continuously through his thickness of the shell, according to a power law distribution of the volume fractions of the constituents.
TL;DR: In this article, a functionally graded rotating disk with axisymmetric bending and steady-state thermal loading is studied, where the material properties of the disk are assumed to be graded in the direction of the thickness by a power law distribution of volume fractions of the constituents.
Abstract: A functionally graded (FG) rotating disk with axisymmetric bending and steady-state thermal loading is studied. The material properties of the disk are assumed to be graded in the direction of the thickness by a power law distribution of volume fractions of the constituents. First-order shear deformation Mindlin plate and von Karman theories are employed. New set of equilibrium equations with small and large deflections are developed. Using small deflection theory an exact solution for displacement field is given. Solutions are obtained in series form in case of large deflection. Mechanical responses are compared small deflection versus large deflection as well as homogeneous versus FG disks. It is observed that for particular values of the grading index n of material properties mechanical responses in FG disk can be smaller than in a homogeneous disk. It is seen that given the non-dimensional maximum vertical displacement wmax/h close to 0.4 for a homogeneous (full-ceramic in this study) disk greater errors in the mechanical responses for FG disks would be introduced if one uses small deflection theory.
TL;DR: In this paper, a stochastic micromechanical model is presented for predicting probabilistic characteristics of elastic mechanical properties of an isotropic functionally graded material (FGM) subject to statistical uncertainties in material properties of constituents and their respective volume fractions.
01 Dec 2007
TL;DR: In this paper, a frequency analysis for functionally graded material (FGM) circular cylindrical shells is performed for algebraic polynomial, exponential, and trigonometric volume fraction laws.
Abstract: In the current paper a frequency analysis is performed for functionally graded material (FGM) circular cylindrical shells. A comparative study of shell frequencies is given for algebraic polynomial, exponential, and trigonometric volume fraction laws. An FGM shell considered here is structured from two materials. Love's thin shell theory is utilized for strain-displacement and curvature-displacement relations. The Rayleigh-Ritz method is employed to derive the frequency equation in the form of eigenvalue problem. Natural frequencies are evaluated for a shell with simply supported edge conditions. The axial modal dependence is approximated by circular trigonometric functions. Theoretical results are compared with those available in the literature for the validity of the present methodology.
TL;DR: In this article, the problem of generalized thermoelastic interactions in a functionally graded isotropic unbounded medium due to the presence of periodically varying heat sources in the context of the linear theory of generalized TEWOED was considered.
TL;DR: In this article, a nonlinear finite element model based on the first-order shear deformable plate theory and von Karman strain-displacement relations is adopted for the nonlinear flutter and thermal buckling of an functionally gradient material panel under the combined effect of elevated temperature conditions and aerodynamic loading.
Abstract: The nonlinear flutter and thermal buckling of an functionally gradient material panel under the combined effect of elevated temperature conditions and aerodynamic loading is studied. A nonlinear finite element model based on the first-order shear deformable plate theory and von Karman strain-displacement relations is adopted. The governing nonlinear equations are obtained using the principal of virtual work, adopting an approach based on the thermal strain being a cumulative physical quantity to account for temperature-dependent material properties. The aerodynamic pressure is modeled using the quasi-steady first-order piston theory. This system of nonlinear equations is solved by the Newton-Raphson numerical technique. It is found that the temperature increase has an adverse effect on the functionally gradient material panel flutter characteristics through decreasing the critical dynamic pressure. Decreasing the volume fraction enhances flutter characteristics, but this is limited by structural integrity aspect. The presence of aerodynamic flow results in postponing the buckling temperature and in suppressing the postbuckling deflection, and the temperature increase gives way for higher limit-cycle amplitude.
TL;DR: In this paper, the effects of the presetting angle, secondary warping, temperature gradient through the wall thickness of the beam and also the rotational speed were investigated for a thin-walled beam made of functionally graded material.
TL;DR: In this article, the axisymmetric bending of two-directional functionally graded circular and annular plates is studied using the semi-analytical numerical method, assuming the material properties varying with an exponential law both in the thickness and radial directions.
TL;DR: In this article, a semi-solid MnSb alloy with a hypoeutectic composition was used to produce particle-dispersed composites under magnetic field gradients.
TL;DR: In this paper, the effect of composition on magneto-thermoelastic stresses and perturbations of the magnetic field vector in FGM hollow cylinders and hollow spheres is determined using the infinitesimal theory of magnetothermasticity.
TL;DR: In this paper, a thermal buckling analysis for functionally graded cylindrical shells that are integrated with surface-bonded piezoelectric actuators and are subjected to the combined action of thermal load and constant applied actuator voltage is presented.
Abstract: A thermal buckling analysis is presented for functionally graded cylindrical shells that are integrated with surface-bonded piezoelectric actuators and are subjected to the combined action of thermal load and constant applied actuator voltage. The material properties are assumed to vary as a power form of the thickness coordinate. Derivation of the equations is based on the higher-order shear deformation shell theory using the Sanders nonlinear kinematic relations. Results for the buckling temperatures are obtained in the closed form solution. The effects of the applied actuator voltage, shell geometry, and volume fraction exponent of functionally graded material on the buckling temperature are investigated. The results for simpler states are validated with known data in the literature.
TL;DR: In this paper, the robust boundary element method (BEM) is used to solve elastic problems with nonlinearly varying material parameters, such as the functionally graded material (FGM) and damage mechanics problems.
Abstract: This paper presents a robust boundary element method (BEM) that can be used to solve elastic problems with nonlinearly varying material parameters, such as the functionally graded material (FGM) and damage mechanics problems. The main feature of this method is that no internal cells are required to evaluate domain integrals appearing in the conventional integral equations derived for these problems, and very few internal points are needed to improve the computational accuracy. In addition, one of the basic field quantities used in the boundary integral equations is normalized by the material parameter. As a result, no gradients of the field quantities are involved in the integral equations. Another advantage of using the normalized quantities is that no material parameters are included in the boundary integrals, so that a unified equation form can be established for multi-region problems which have different material parameters. This is very efficient for solving composite structural problems.
TL;DR: In this paper, the authors investigated three-dimensional elastic flexural behavior of an adhesively bonded single lap joint with adherends composed of a functionally gradient layer between a pure ceramic layer and a pure metal layer.
TL;DR: In this article, the stress to strain transfer ratio for Al/SiC composite system was determined from the flexural load-deflection behavior of single-layer beams of different compositions (10, 20 and 30% of SiC).
Abstract: The stress to strain transfer ratio for aluminium-silicon carbide (Al/SiC) composite system is experimentally determined from the flexural load-deflection behavior of single-layer beams of different compositions (10, 20 and 30% of SiC). This ratio can be used for predicting the elastic modulus of the Al/SiC functionally graded material using an intermediate rule of mixtures. Using this data, the static flexural response of a layered functionally graded beam of Al/SiC with five layers of equal thickness with SiC content varying from 0 to 40%, is predicted employing a third-order zigzag theory. The predicted deflection is found to be in fairly close agreement with the experimental results.
TL;DR: In this article, the influence of an interlayer's construction and thickness on thermal residual stresses generated in ceramic-metal joints was analyzed using the finite elements method (FEM) for the Al 2 O 3 ceramics-heat resisting steel joint.
Abstract: The present paper analyses the influence of an interlayer's construction and thickness on thermal residual stresses generated in ceramic–metal joints. Numerical calculations (the finite elements method—FEM) of the state of thermal residual stresses, as well as the verifying technological tests, were made for the following pair of materials: the Al 2 O 3 ceramics–heat resisting steel. The model reference system was the direct joint of these materials. The results presented in this paper concern the influence of the type of a gradient material (various thickness, various construction profile—understood as the number of layers, various Al 2 O 3 –Cr composition and mutual position) on the state of residual stress in the joint. The numerical calculations carried out on the state of residual stresses showed that for the assumed composition and thickness of the gradient material it is possible to further lower the level of stresses in the ceramic element of the analyzed joint by modifying the profile of a gradient material's inner structure. It was found that the dangerous stresses concentration area was shifted from the bonding line ceramic/FGM layer (of relatively low strength) further into the FGM's layer, i.e. to the dividing line layer I (75Al 2 O 3 /25Cr)/layer II (50Al 2 O 3 /50Cr), of much higher strength.