• 제목, 요약, 키워드: Functionally Graded Material

검색결과 587건 처리시간 0.045초

An efficient shear deformation theory for wave propagation in functionally graded material beams with porosities

  • Benadouda, Mourad;Atmane, Hassen Ait;Tounsi, Abdelouahed;Bernard, Fabrice;Mahmoud, S.R.
    • Earthquakes and Structures
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    • v.13 no.3
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    • pp.255-265
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    • 2017
  • In this paper, an efficient shear deformation theory is developed for wave propagation analysis in a functionally graded beam. More particularly, porosities that may occur in Functionally Graded Materials (FGMs) during their manufacture are considered. The proposed shear deformation theory is efficient method because it permits us to show the effect of both bending and shear components and this is carried out by dividing the transverse displacement into the bending and shear parts. Material properties are assumed graded in the thickness direction according to a simple power law distribution in terms of the volume fractions of the constituents; but the rule of mixture is modified to describe and approximate material properties of the functionally graded beams with porosity phases. The governing equations of the wave propagation in the functionally graded beam are derived by employing the Hamilton's principle. The analytical dispersion relation of the functionally graded beam is obtained by solving an eigenvalue problem. The effects of the volume fraction distributions, the depth of beam, the number of wave and the porosity on wave propagation in functionally graded beam are discussed in details. It can be concluded that the present theory is not only accurate but also simple in predicting the wave propagation characteristics in the functionally graded beam.

Fracture analysis of functionally graded beams with considering material non-linearity

  • Rizov, Victor I.
    • Structural Engineering and Mechanics
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    • v.64 no.4
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    • pp.487-494
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    • 2017
  • The present paper deals with a theoretical study of delamination fracture in the Crack Lap Shear (CLS) functionally graded beam configuration. The basic purpose is to analyze the fracture with taking into account the material non-linearity. The mechanical behavior of CLS was described by using a non-linear stress-strain relation. It was assumed that the material is functionally graded along the beam height. The fracture was analyzed by applying the J-integral approach. The curvature and neutral axis coordinate of CLS beam were derived in order to solve analytically the J-integral. The non-linear solution of J-integral obtained was verified by analyzing the strain energy release rate with considering material non-linearity. The effects of material gradient, crack location along the beam height and material non-linearity on fracture behavior were evaluated. The J-integral non-linear solution derived is very suitable for parametric studies of longitudinal fracture in the CLS beam. The results obtained can be used to optimize the functionally graded beam structure with respect to the fracture performance. The analytical approach developed in the present paper contributes for the understanding of delamination fracture in functionally graded beams exhibiting material non-linearity.

Non-linear study of mode II delamination fracture in functionally graded beams

  • Rizov, Victor I.
    • Steel and Composite Structures
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    • v.23 no.3
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    • pp.263-271
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    • 2017
  • A theoretical study was carried-out of mode II delamination fracture behavior of the End Loaded Split (ELS) functionally graded beam configuration with considering the material non-linearity. The mechanical response of ELS was modeled analytically by using a power-law stress-strain relation. It was assumed that the material is functionally graded transversally to the beam. The non-linear fracture was investigated by using the J-integral approach. Equations were derived for the crack arm curvature and zero axes coordinate that are needed for the J-integral solution. The analysis developed is valid for a delamination crack located arbitrary along the beam height. The J-integral solution was verified by analyzing the strain energy release rate with considering material non-linearity. The effects of material gradient, non-linear material behavior and crack location on the fracture were evaluated. The solution derived is suitable for parametric analyses of non-linear fracture. The results obtained can be used for optimization of functionally graded beams with respect to their mode II fracture performance. Also, such simplified analytical models contribute for the understanding of delamination fracture in functionally graded beams exhibiting material non-linearity.

Wave propagation in functionally graded plates with porosities using various higher-order shear deformation plate theories

  • Yahia, Sihame Ait;Atmane, Hassen Ait;Houari, Mohammed Sid Ahmed;Tounsi, Abdelouahed
    • Structural Engineering and Mechanics
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    • v.53 no.6
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    • pp.1143-1165
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    • 2015
  • In this work, various higher-order shear deformation plate theories for wave propagation in functionally graded plates are developed. Due to porosities, possibly occurring inside functionally graded materials (FGMs) during fabrication, it is therefore necessary to consider the wave propagation in plates having porosities in this study. The developed refined plate theories have fewer number of unknowns and equations of motion than the first-order shear deformation theory, but accounts for the transverse shear deformation effects without requiring shear correction factors. The rule of mixture is modified to describe and approximate material properties of the functionally graded plates with porosity phases. The governing equations of the wave propagation in the functionally graded plate are derived by employing the Hamilton's principle. The analytic dispersion relation of the functionally graded plate is obtained by solving an eigenvalue problem. The effects of the volume fraction distributions and porosity volume fraction on wave propagation of functionally graded plate are discussed in detail. The results carried out can be used in the ultrasonic inspection techniques and structural health monitoring.

경사기능재료에서의 열탄성 불안정성 (Thermoelastic Instability in Functionally Graded Materials)

  • 장용훈;안성호;이승욱
    • 한국자동차공학회논문집
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    • v.14 no.5
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    • pp.130-137
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    • 2006
  • A transient finite element simulation is developed for the two-dimensional thermoelastic contact problem of a stationary functionally graded material between sliding layers, with frictional heat generation. Thermoelastic instability in functionally graded materials is investigated. The critical speed of functionally graded material coating disk is larger than that of the conventional steel disk. The effect of the nonhomogeneity parameter in functionally graded material is also investigated. The results show that functionally gradient materials restrain the growth of perturbation and delay the contact separation.

An efficient shear deformation theory for wave propagation of functionally graded material plates

  • Boukhari, Ahmed;Atmane, Hassen Ait;Tounsi, Abdelouahed;Adda Bedia, E.A.;Mahmoud, S.R.
    • Structural Engineering and Mechanics
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    • v.57 no.5
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    • pp.837-859
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    • 2016
  • An efficient shear deformation theory is developed for wave propagation analysis of an infinite functionally graded plate in the presence of thermal environments. By dividing the transverse displacement into bending and shear parts, the number of unknowns and governing equations of the present theory is reduced, and hence, makes it simple to use. The thermal effects and temperature-dependent material properties are both taken into account. The temperature field is assumed to be a uniform distribution over the plate surface and varied in the thickness direction only. Material properties are assumed to be temperature-dependent, and graded in the thickness direction according to a simple power law distribution in terms of the volume fractions of the constituents. The governing equations of the wave propagation in the functionally graded plate are derived by employing the Hamilton's principle and the physical neutral surface concept. There is no stretching.bending coupling effect in the neutral surface-based formulation, and consequently, the governing equations and boundary conditions of functionally graded plates based on neutral surface have the simple forms as those of isotropic plates. The analytic dispersion relation of the functionally graded plate is obtained by solving an eigenvalue problem. The effects of the volume fraction distributions and temperature on wave propagation of functionally graded plate are discussed in detail. It can be concluded that the present theory is not only accurate but also simple in predicting the wave propagation characteristics in the functionally graded plate. The results carried out can be used in the ultrasonic inspection techniques and structural health monitoring.

A simple analytical approach for thermal buckling of thick functionally graded sandwich plates

  • El-Haina, Fouzia;Bakora, Ahmed;Bousahla, Abdelmoumen Anis;Tounsi, Abdelouahed;Mahmoud, S.R.
    • Structural Engineering and Mechanics
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    • v.63 no.5
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    • pp.585-595
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    • 2017
  • This study aimed to presents a simple analytical approach to investigate the thermal buckling behavior of thick functionally graded sandwich by employing both the sinusoidal shear deformation theory and stress function. The material properties of the sandwich plate faces are continuously varied within the plate thickness according to a simple power-law distribution in terms of the volume fractions of the constituents. The core layer is still homogeneous and made of an isotropic material. The thermal loads are considered as uniform, linear and non-linear temperature rises across the thickness direction. Numerical examples are presented to prove the effect of power law index, loading type and functionally graded layers thickness on the thermal buckling response of thick functionally graded sandwich.

Non-linear longitudinal fracture in a functionally graded beam

  • Rizov, Victor I.
    • Coupled systems mechanics
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    • v.7 no.4
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    • pp.441-453
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    • 2018
  • Longitudinal fracture in a functionally graded beam configuration was studied analytically with taking into account the non-linear behavior of the material. A cantilever beam with two longitudinal cracks located symmetrically with respect to the centroid was analyzed. The material was functionally graded along the beam width as well as along the beam length. The fracture was studied in terms of the strain energy release rate. The influence of material gradient, crack location along the beam width, crack length and material non-linearity on the fracture behavior was investigated. It was shown that the analytical solution derived is very useful for parametric analyses of the non-linear longitudinal fracture behavior. It was found that by using appropriate material gradients in width and length directions of the beam, the strain energy release rate can be reduced significantly. Thus, the results obtained in the present paper may be applied for optimization of functionally graded beam structure with respect to the longitudinal fracture performance.

Geometrically nonlinear analysis of functionally graded porous beams

  • Akbas, Seref D.
    • Wind and Structures
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    • v.27 no.1
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    • pp.59-70
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    • 2018
  • In this paper, geometrically non-linear analysis of a functionally graded simple supported beam is investigated with porosity effect. The material properties of the beam are assumed to vary though height direction according to a prescribed power-law distributions with different porosity models. In the nonlinear kinematic model of the beam, the total Lagrangian approach is used within Timoshenko beam theory. In the solution of the nonlinear problem, the finite element method is used in conjunction with the Newton-Raphson method. In the study, the effects of material distribution such as power-law exponents, porosity coefficients, nonlinear effects on the static behavior of functionally graded beams are examined and discussed with porosity effects. The difference between the geometrically linear and nonlinear analysis of functionally graded porous beam is investigated in detail. Also, the effects of the different porosity models on the functionally graded beams are investigated both linear and nonlinear cases.

경사기능재료의 설계에 관한 연구 (A Study on Design of Functionally graded Materials)

  • 최덕기;경사기
    • 한국자동차공학회논문집
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    • v.6 no.2
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    • pp.144-154
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    • 1998
  • A functionally graded material is a nonhomogeneous material, which is composed of several different materials to maintain structural rigidity and endure high temperature loads. An analytical method is presenter to solve the unsteady heat conduction equation for nonhomogeneous materials. A one-dimensional infinite plate made of functionally graded material is considered. The approximate Green's function solution is derived and to be used to obtain the temperature distribution them the stress distributions may be obtained. The volume fraction, the porosity, the stress difference, and the stress ratio are the design parameters and are to be used to set up a systematic design procedure.

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