• Title, Summary, Keyword: Functionally Graded Material

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An efficient and simple four variable refined plate theory for buckling analysis of functionally graded plates

  • Bellifa, Hichem;Bakora, Ahmed;Tounsi, Abdelouahed;Bousahla, Abdelmoumen Anis;Mahmoud, S.R.
    • Steel and Composite Structures
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    • v.25 no.3
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    • pp.257-270
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    • 2017
  • In this article, an efficient and simple refined theory is proposed for buckling analysis of functionally graded plates by using a new displacement field which includes undetermined integral variables. This theory contains only four unknowns, with is even less than the first shear deformation theory (FSDT). Governing equations are obtained from the principle of virtual works. The closed-form solutions of rectangular plates are determined. Comparison studies are carried out to check the validity of obtained results. The influences of loading conditions and variations of power of functionally graded material, modulus ratio, aspect ratio, and thickness ratio on the critical buckling load of functionally graded plates are examined and discussed.

Micromechanics Modeling of Functionally Graded Materials Containing Multiple Heterogeneities

  • Yu, Jaesang;Yang, Cheol-Min;Jung, Yong Chae
    • Composites Research
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    • v.26 no.6
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    • pp.392-397
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    • 2013
  • Functionally graded materials graded continuously and discretely, and are modeled using modified Mori- Tanaka and self-consistent methods. The proposed micromechanics model accounts for multi-phase heterogeneity and arbitrary number of layers. The influence of geometries and distinct elastic material properties of each constituent and voids on the effective elastic properties of FGM is investigated. Numerical examples of different functionally graded materials are presented. The predicted elastic properties obtained from the current model agree well with experimental results from the literature.

Mechanical strength analysis for functionally graded composite plates (경사기능 복합재료 판의 기계적 강도해석)

  • Na, Kyung-Su;Kim, Ji-Hwan
    • Proceedings of the Korean Society For Composite Materials Conference
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    • pp.66-69
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    • 2005
  • Mechanical strength of functionally graded composite plates that composed of ceramic, functionally graded material and metal layers is investigated using 3-D finite element method. In FGM layer, material properties are assumed to be varied continuously in the thickness direction according to a simple power law distribution in terms of the volume fraction of a ceramic and metal. The 3-D finite element model is adopted by using an IS-node solid element to analyze more accurately the variation of material properties in the thickness direction. Numerical results are compared with those of the previous works. In addition, the displacements, the tensile stresses and the compressive stresses are analyzed for the variation of FGM thickness ratio and volume fraction distribution.Mechanical strength of functionally graded composite plates that composed of ceramic, functionally graded material and metal layers is investigated using 3-D finite element method. In FGM layer, material properties are assumed to be varied continuously in the thickness direction according to a simple power law distribution in terms of the volume fraction of a ceramic and metal. The 3-D finite element model is adopted by using an IS-node solid element to analyze more accurately the variation of material properties in the thickness direction. Numerical results are compared with those of the previous works. In addition, the displacements, the tensile stresses and the compressive stresses are analyzed for the variation of FGM thickness ratio and volume fraction distribution.

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Dynamic Characteristics of an Eccentric Crack in a Functionally Graded Piezoelectric Ceramic Strip

  • Shin, Jeong-Woo;Kim, Tae-Uk;Kim, Sung-Chan
    • Journal of Mechanical Science and Technology
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    • v.18 no.9
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    • pp.1582-1589
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    • 2004
  • The dynamic response of an eccentric Griffith crack in functionally graded piezoelectric ceramic strip under anti-plane shear impact loading is ana lysed using integral transform method. Laplace transform and Fourier transform are used to reduce the problem to two pairs of dual integral equations, which are then expressed to Fredholm integral equations of the second kind. We assume that the properties of the functionally graded piezoelectric material vary continuously along the thickness. The impermeable crack boundary condition is adopted. Numerical values on the dynamic stress intensity factors are presented for the functionally graded piezoelectric material to show the dependence of the gradient of material properties and electric loadings.

Analysis of functionally graded plates using a sinusoidal shear deformation theory

  • Hadji, Lazreg
    • Smart Structures and Systems
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    • v.19 no.4
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    • pp.441-448
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    • 2017
  • This paper uses the four-variable refined plate theory for the free vibration analysis of functionally graded material (FGM) rectangular plates. The plate properties are assumed to be varied through the thickness following a simple power law distribution in terms of volume fraction of material constituents. The theory presented is variationally consistent, does not require shear correction factor, and gives rise to transverse shear stress variation such that the transverse shear stresses vary parabolically across the thickness satisfying shear stress free surface conditions. Equations of motion are derived from the Hamilton's principle. The closed-form solutions of functionally graded plates are obtained using Navier solution. Numerical results of the refined plate theory are presented to show the effect of the material distribution, the aspect and side-to-thickness ratio on the fundamental frequencies. It can be concluded that the proposed theory is accurate and simple in solving the free vibration behavior of functionally graded plates.

Exact analysis of bi-directional functionally graded beams with arbitrary boundary conditions via the symplectic approach

  • Zhao, Li;Zhu, Jun;Wen, Xiao D.
    • Structural Engineering and Mechanics
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    • v.59 no.1
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    • pp.101-122
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    • 2016
  • Elasticity solutions for bi-directional functionally graded beams subjected to arbitrary lateral loads are conducted, with emphasis on the end effects. The material is considered macroscopically isotropic, with Young's modulus varying exponentially in both axial and thickness directions, while Poisson's ratio remaining constant. In order to obtain an exact analysis of stress and displacement fields, the symplectic analysis based on Hamiltonian state space approach is employed. The capability of the symplectic framework for exact analysis of bi-directional functionally graded beams has been validated by comparing numerical results with corresponding ones in open literature. Numerical results are provided to demonstrate the influences of the material gradations on localized stress distributions. Thus, the material properties of the bi-directional functionally graded beam can be tailored for the potential practical purpose by choosing suitable graded indices.

Electromagnetothermoelastic behavior of a rotating imperfect hybrid functionally graded hollow cylinder

  • Saadatfar, M.;Aghaie-Khafri, M.
    • Smart Structures and Systems
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    • v.15 no.6
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    • pp.1411-1437
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    • 2015
  • The electro-magneto- thermo-elastic behavior of a rotating functionally graded long hollow cylinder with functionally graded piezoelectric (FGPM) layers is analytically analyzed. The layers are imperfectly bonded to its inner and outer surfaces. The hybrid cylinder is placed in a constant magnetic field subjected to a thermo-electro-mechanical loading and could be rested on a Winkler-type elastic foundation. The material properties of the FGM cylinder and radially polarized FGPM layers are assumed to be graded in the radial direction according to the power law. The hybrid cylinder is rotating about its axis at a constant angular velocity. The governing equations are solved analytically and then stresses, displacement and electric potential distribution are calculated. Numerical examples are given to illustrate the effects of material in-homogeneity, magnetic field, elastic foundation, applied voltage, imperfect interface and thermo-mechanical boundary condition on the static behavior of a FG smart cylinder.

Processing of Functionally Graded Materials via Green Tape Lamination

  • Cho, Yu-Jeong;Kim, Yong-Seog
    • Proceedings of the Korean Powder Metallurgy Institute Conference
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    • pp.78-79
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    • 2003
  • A functionally graded material was produced by laminating green tapes. The lamination resulted in the formation of functionally graded structure and sintering of the materials resulted of FGM. This results demonstrated a possibility of using green tapes in the processing of functionally graded materials.

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The Evaluation of Crack Propagation in Functionally Graded Materials with Coatings (코팅 경사기능 재료의 균열전파에 관한 평가)

  • Kwon, Oh-Heon
    • Journal of the Korean Society of Safety
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    • v.23 no.4
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    • pp.25-29
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    • 2008
  • Recently, new functionally graded material(FGM) that has a spatial variation in composition and properties is developed because of its good quality. This material yields the demands for resistance to corrosion and high temperature in turbine blade, wear resistance as in gears and high strength machine parts. Especially coating treatment in FGM surface brings forth a mechanical weak at the interface due to discontinuous stress resulting from a steep material change. It often, leads cracks or spallation in a coating area around an interface. The behavior of propagation cracks in FGMs was here investigated. The interface stresses were reduced because of graded material properties. Also graded material parameter with exponential equation was founded to influence the stress intensity factor. And the resistance curve with FGM coating was slightly increased.

An analytical approach for buckling of functionally graded plates

  • Daouadji, Tahar Hassaine;Adim, Belkacem
    • Advances in materials Research
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    • v.5 no.3
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    • pp.141-169
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    • 2016
  • In this paper, an efficient and simple refined theory is presented for buckling analysis of functionally graded plates. The theory, which has strong similarity with classical plate theory in many aspects, accounts for a quadratic variation of the transverse shear strains across the thickness and satisfies the zero traction boundary conditions on the top and bottom surfaces of the plate without using shear correction factors. The mechanical properties of functionally graded material are assumed to vary according to a power law distribution of the volume fraction of the constituents. Governing equations are derived from the principle of minimum total potential energy. The closed-form solutions of rectangular plates are obtained. Comparison studies are performed to verify the validity of present results. The effects of loading conditions and variations of power of functionally graded material, modulus ratio, aspect ratio, and thickness ratio on the critical buckling load of functionally graded plates are investigated and discussed.