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Showing papers on "Functionally graded material published in 2019"


Journal ArticleDOI
TL;DR: In this article, a new shear deformation plate theory is introduced to illustrate the bending, buckling and free vibration responses of functionally graded material sandwich plates, and a new displacemen...
Abstract: In this study, a new shear deformation plate theory is introduced to illustrate the bending, buckling and free vibration responses of functionally graded material sandwich plates. A new displacemen...

104 citations


Journal ArticleDOI
TL;DR: This study shows the great potential of AM functionally graded porous iron as a bone substituting material and demonstrates that complex topological design permits the control of mechanical properties, degradation behavior of AM porous metallic biomaterials.

103 citations


Journal ArticleDOI
TL;DR: In this paper, the size-dependent effects on thermal buckling and post-buckling behaviors of imperfect FGM micro-plates with porosities were analyzed using isogeometric analysis.

102 citations


DOI
01 Sep 2019
TL;DR: In this paper, a non-local nth-order shear deformation analysis of functionally graded (FG) porous nano-beams is studied based on a power-law scheme, which is modified to approximate material characteristics for considering the influence of porosities.
Abstract: In this work, dynamic behavior of functionally graded (FG) porous nano-beams is studied based on nonlocal nth-order shear deformation theory which takes into the effect of shear deformation without considering shear correction factors. It has been observed that during the manufacture of "functionally graded materials" (FGMs), micro-voids and porosities can occur inside the material. Thus, in this work, the investigation of the dynamic analysis of FG beams taking into account the influence of these imperfections is established. Material characteristics of the FG beam are supposed to be vary continuously within thickness direction according to a "power-law scheme" which is modified to approximate material characteristics for considering the influence of porosities. A comparative study with the known results in the literature confirms the accuracy and efficiency of the current nonlocal nth-order shear deformation theory

92 citations


Journal ArticleDOI
TL;DR: In this paper, the authors fabricate functionally graded transition joints between a ferritic and austenitic alloy, characterize spatial variations of chemical composition, microstructure and hardness, and test their effectiveness to limit carbon loss from the ferritic alloy.

75 citations


Journal ArticleDOI
TL;DR: In this paper, the static and dynamic responses of bi-directional functionally graded (BDFG) microbeams are investigated using von-Karman geometric nonlinearity and third-order shear deformation beam theory.

68 citations


Journal ArticleDOI
TL;DR: In this article, a total of five different types of specimens were additively manufactured by directed energy deposition (DED) process and the residual stress distributions were experimentally measured through the thickness of the specimens by the contour method, neutron diffraction, and deep/incremental center hole drilling.
Abstract: A total of five different types of specimens were additively manufactured by directed energy deposition (DED) process. The specimens have a functionally graded material (FGM) structure, which has been deposited with variation of chemical composition of ferritic and austenitic steel powders in each interlayer on a steel substrate. Residual stress distributions were experimentally measured through the thickness of the specimens by the contour method, neutron diffraction, and deep/incremental center hole drilling. Neutron diffraction provided three orthogonal stress components in each FGM part and the results were compared to the two-dimensional stress map obtained by the contour method and confirmed its criticalities from the highly spatial resolved depth profile by the hole drilling method. Significant variations from tension to compression (up to 950 MPa) in the sine-wave stress profile were alleviated to about 430 MPa when the FGM were deposited with orthogonal or island DED scanning strategies with interlayers. Gradual changes (16.3–12.1 × 10−6/°C) of the thermal expansion coefficient were measured among the inserted DED FGM parts and grain structure with defects along the interface was three dimensionally examined by neutron tomography.

66 citations


Journal ArticleDOI
TL;DR: In this paper, a nonlinear dynamics of fluid-conveying functionally graded material (FGM) sandwich nanoshells is investigated, where the von Karman nonlinear geometrical relations are taken into account, compressibility and viscidity of the fluid are neglected, and the velocity potential and Bernoulli's equation are used to describe the fluid pressure acting on the nano-shells.
Abstract: In the present work, nonlinear dynamics of fluid-conveying functionally graded material (FGM) sandwich nanoshells is investigated. In order to describe the large-amplitude motion, the von Karman nonlinear geometrical relations are taken into account. Compressibility and viscidity of the fluid are neglected, and the velocity potential and Bernoulli's equation are used to describe the fluid pressure acting on the nanoshells. Based on the classical shell theory and incorporating the surface stress effect, the governing equations are derived by using Hamilton's principle. After that, the Galerkin method is used to discretize the equation of motion, resulting in a set of ordinary differential equations with respect to time. The ordinary differential equations are solved analytically by utilizing the method of multiple scales. Results show that the surface stress plays important roles on the nonlinear vibration characteristics of fluid-conveying FGM sandwich thin-walled nanoshells. Furthermore, the fluid speed, the power-law index, the fluid mass density, the core thickness and the initial surface tension can also influence the vibration characteristics of fluid-conveying FGM sandwich nanoshells.

63 citations


Journal ArticleDOI
TL;DR: In this paper, a tungsten-copper functionally graded material was processed based on SLM additive manufacture despite encountering some difficulties from materials characters, and the effect of laser parameter on the interfacial defects and bonding performance were evaluated.

60 citations


Journal ArticleDOI
TL;DR: In this article, a simple quasi-3D shear deformation theory is employed for thermo-mechanical bending analysis of functionally graded material (FGM) sandwich plates.
Abstract: In this article, a simple quasi-3D shear deformation theory is employed for thermo-mechanical bending analysis of functionally graded material (FGM) sandwich plates. The displacement field is defined using only 5 variables as the first order shear deformation theory (FSDT). Unlike the other high order shear deformation theories (HSDTs), the present formulation considers a new kinematic which includes undetermined integral variables. The governing equations are determined based on the principle of virtual work and then they are solved via Navier method. Analytical solutions are proposed to provide the deflections and stresses of simply supported FGM sandwich structures. Comparative examples are presented to demonstrate the accuracy of the present theory. The effects of gradient index, geometrical parameters and thermal load on thermo-mechanical bending response of the FG sandwich plates are examined.

60 citations


Journal ArticleDOI
TL;DR: In this article, the influence of various homogenization models on the free vibration behavior of a functionally graded material (FGM) curved microbeam is studied using the modified strain gradient theory of elasticity as well as the first-order shear deformation theory.

Journal ArticleDOI
TL;DR: In this article, a unified model for the force resonance problem of a three-directional functionally graded material (3D-FGM) was presented, and the resonance behavior of Kirchhoff nanoplates was investigated using the variational approach.

Journal ArticleDOI
TL;DR: In this paper, a complete design and manufacturing workflow that simultaneously integrates material design, structural design, and product fabrication of functionally graded material (FGM) structures based on digital materials is presented.
Abstract: Voxel-based multimaterial jetting additive manufacturing allows fabrication of digital materials (DMs) at the meso-scale (∼1 mm) by controlling the deposition patterns of soft elastomeric and rigid glassy polymers at the voxel-scale (∼90 μm). The digital materials can then be used to create heterogeneous functionally graded material (FGM) structures at the macro-scale (∼10 mm) programmed to behave in a predefined manner. This offers huge potential for design and fabrication of novel and complex bespoke mechanical structures. This paper presents a complete design and manufacturing workflow that simultaneously integrates material design, structural design, and product fabrication of FGM structures based on digital materials. This is enabled by a regression analysis of the experimental data on mechanical performance of the DMs i.e., Young’s modulus, tensile strength and elongation at break. This allows us to express the material behavior simply as a function of the microstructural descriptors (in this case, just volume fraction) without having to understand the underlying microstructural mechanics while simultaneously connecting it to the process parameters. Our proposed design and manufacturing approach is then demonstrated and validated in two series of design exercises to devise complex FGM structures. First, we design, computationally predict and experimentally validate the behavior of prescribed designs of FGM tensile structures with different material gradients. Second, we present a design automation approach for optimal FGM structures. The comparison between the simulations and the experiments with the FGM structures shows that the presented design and fabrication workflow based on our modeling approach for DMs at meso-scale can be effectively used to design and predict the performance of FGMs at macro-scale.

Journal ArticleDOI
TL;DR: In this article, two higher order transverse shear deformation theories (NHSDTs) with five variables have been proposed for the analysis of Functionally Graded Material (FGM) plate.

Journal ArticleDOI
15 Mar 2019
TL;DR: In this article, a new porosities distribution is proposed for bending analysis of new model of functionally graded material (FGM) sandwich plates, where the face layers are considered to be FG across each face thickness while the core is made of a ceramic homogeneous layer.
Abstract: A new porosities distribution is proposed for bending analysis of new model of functionally graded material (FGM) sandwich plates. Material properties of FGM layers are assumed to vary continuously across the plate thickness according to either power-law or sigmoid function in terms of the volume fractions of the constituents. The face layers are considered to be FG across each face thickness while the core is made of a ceramic homogeneous layer. New higher-order deformation theory is proposed to derive the field equations of the FG sandwich plates with simply-supported edge conditions. Numerical results are presented to show the effect of the material distribution, the sandwich plate geometry and the porosity on the deflections and stresses of FG sandwich plates. The accuracy of this theory is ascertained by comparing it with other published results.

Journal ArticleDOI
TL;DR: In this article, a quasi-3D beam theory is developed for free vibration analysis of functionally graded microbeams, where volume fractions of metal and ceramic are assumed to be distributed through a beam thickness by three functions, power function, symmetric power function and sigmoid law distribution.
Abstract: In the current research paper, a quasi-3D beam theory is developed for free vibration analysis of functionally graded microbeams. The volume fractions of metal and ceramic are assumed to be distributed through a beam thickness by three functions, power function, symmetric power function and sigmoid law distribution. The modified coupled stress theory is used to incorporate size dependency of micobeam. The equation of motion is derived by using Hamilton\'s principle, however, Navier type solution method is used to obtain frequencies. Numerical results show the effects of the function distribution, power index and material scale parameter on fundamental frequencies of microbeams. This model provides designers with guidance to select the proper distributions and functions.

Journal ArticleDOI
TL;DR: In this article, the effect of source-uncertainties on low-velocity impact of functionally graded material (FGM) plates following a coupled surrogate based finite element simulation approach is quantified.
Abstract: This paper quantifies the compound effect of source-uncertainties on low-velocity impact of functionally graded material (FGM) plates following a coupled surrogate based finite element simulation approach. The power law is employed to evaluate the material properties of FGM plate at different points, while the modified Hertzian contact law is implemented to determine the contact force and other parameters in a stochastic framework. The time dependent equations are solved by Newmark's time integration scheme. Insightful results are presented by investigating the effects of degree of stochasticity, oblique impact angle, thickness of plate, temperature, power law index, and initial velocity of impactor following both probabilistic and non-probabilistic approaches along with in-depth deterministic analyses. A detail probabilistic analysis leading to complete probabilistic characterization of the structural responses can be carried out when the statistical distribution of the stochastic input parameters are available. However, in many cases concerning FGM, these statistical distributions may remain unavailable due to the restriction of performing large number of experiments. In such situations, a fuzzy-based non-probabilistic approach could be appropriate to characterize the effect of uncertainty. A surrogate based approach based on artificial neural network coupled with the finite element model for low-velocity impact analysis of FGM plates is developed for achieving computational efficiency. The numerical results reveal that the low-velocity impact on FGM plates is significantly influenced by the effect of inevitable source-uncertainty associated with the stochastic system parameters, whereby the importance of adopting an inclusive design paradigm considering the effect of source-uncertainties in the impact analysis is established.

Journal ArticleDOI
TL;DR: In this article, the stability of a rectangular functionally grade material (FGM) plate with central crack is studied. And the results of the study are compared with the published articles to ensure credibility, and some visual images of the mechanical instability forms of cracked FGM plates are introduced.
Abstract: In this paper, the stability in a rectangular functionally grade material (FGM) plate with central crack is studied. The plate thickness is changed exponentially following the length of the plate. The properties of the FGM plate are assumed to vary along the thickness direction according to a simple power law distribution. Based on the phase-field theory, the new third order shear deformation plate theory (TSDT) and the finite element method (FEM), the stability of cracked FGM plate is determined. The obtained numerical results are compared with the published articles to ensure credibility. The work also considered effects of changing of the plate thickness ratio, length, crack angle and volume fraction exponent of the functionally graded material on the stability of the plate. Lastly, some visual images of the mechanical instability forms of cracked FGM plates will be introduced.

Journal ArticleDOI
TL;DR: In this article, a 3D finite element based mathematical model is proposed to predict the thermal gradient of CFSW considering a material flow pattern of dissimilar Al-Cu joint, and a definite heat transfer mathematical model between tool and workpiece interaction and Gaussian based cooling sources is employed in simulation.

Journal ArticleDOI
TL;DR: In this article, a truncated cone insulator with permittivity FGM was designed to relieve local electric field (E-field) enhancement at the triple junctions, and the optimal values of several model parameters were determined based on the analysis of E-field uniformity.
Abstract: Dielectrics with functionally graded material (d-FGM), which have spatially nonuniform dielectric properties, is effective to improve the insulation performance without complicating the structure. In the application of d-FGM, searching the optimal distribution of dielectric properties (permittivity or conductivity) is the most important goal, which however is difficult for conventional insulation design approaches. In this paper, the topology optimization technique is introduced to design a truncated cone insulator with permittivity FGM, which is to relieve local electric field (E-field) enhancement at the triple junctions. Firstly, a multi-objective topology optimization model is proposed using the variable density method. Secondly, the optimal values of several model parameters are determined based on the analysis of E-field uniformity. Finally, finite elements calculation demonstrates that the E-field uniformity is significantly improved for the topology-optimized permittivity FGM, and the E-field enhancement at triple junctions is strongly inhibited. It is thus expected that by applying the topology-optimized permittivity FGM insulator, the breakdown strength in gas or vacuum would be effectively improved.

Journal ArticleDOI
TL;DR: In this paper, the effects of different volume fractions, FG profiles and shell characteristics on the critical parameters of FGM cylindrical shells with mixed boundary conditions (MBCs) are studied in detail.
Abstract: The vibration and stability problems of functionally graded material (FGM) cylindrical shells subjected to external pressures with mixed boundary conditions (MBCs) using first order shear deformation theory (FOSDT) is studied. The governing equations of FGM cylindrical shells (FGMCSs) are displayed according to the Donnell type shell theory and solved using the Galerkin's method. The novelty in this study is to obtain closed-form solutions of the eigen-value problem in mixed boundary conditions within the framework of the FOSDT. Finally, the effects of different volume fractions, FG profiles and shell characteristics on the critical parameters of FGMCSs with MBCs are studied in detail.

Journal ArticleDOI
TL;DR: The overall robustness of the new developed solution taking into account both geometric and material nonlinearities is demonstrated through several non-trivial benchmark problems taken from the literature.
Abstract: A geometrically nonlinear analysis of elastoplastic ceramic/metal functionally graded material (FGM) shells is investigated in this paper based on the first-order shear deformation theory. The elastoplastic behavior of the ceramic particle-reinforced metal matrix FGM shell is assumed to follow Ludwik hardening law. The elastoplastic material properties are assumed to vary smoothly through the thickness of the shells. The Mori–Tanaka model and self-consistent formulas of Suquet are employed to locally evaluate effective elastoplastic parameters of the ceramic/metal FGM composite. The homogenization formulation and numerical algorithms are implemented into ABAQUS/Standard via a user material subroutine (UMAT) developed to study the FG shells in large displacements and rotations. With the aim of demonstrating the accuracy of the present method, current numerical results are compared to experimental and numerical ones considering geometrically nonlinear elastoplastic FGMs and show very good agreement. The overall robustness of the new developed solution taking into account both geometric and material nonlinearities is demonstrated through several non-trivial benchmark problems taken from the literature. The effect of the constituent distribution on the deflections is analyzed.

Journal ArticleDOI
TL;DR: In this paper, free vibration and buckling characteristics of a sandwich functionally graded material (FGM) plate resting on the Pasternak elastic foundation have been investigated, and the form of the plate has been shown to be stable.
Abstract: In the present study, free vibration and buckling characteristics of a sandwich functionally graded material (FGM) plate resting on the Pasternak elastic foundation have been investigated. The form...

Journal ArticleDOI
TL;DR: In this paper, the authors studied the thermo-elastic vibration of axially functionally graded material (FGM) pipe conveying fluid considering temperature changes and the governing equation based on Euler-Bernoulli beam theory is solved by differential quadrature method.
Abstract: In this article, we study the thermo-elastic vibration of axially functionally graded material (FGM) pipe conveying fluid considering temperature changes. The governing equation based on Euler–Bernoulli beam theory is solved by differential quadrature method. The FGM properties are defined by the property ratios and the volume fraction functions. Power volume fraction function and exponent volume fraction function are compared. We also use sigmoid volume fraction functions so that the exclusive influence of function distribution can be isolated from that of total material proportions. The property ratios’ effects of elasticity and thermo-elasticity gradient are also discussed. Based on the numerical results of first-order dimensionless frequencies and critical flow velocities, concerning thermo-elasticity gradient can theoretically change the stability of the pipe. And the influences of the pure distribution on the first-order critical flow velocities are much smaller than that of the varying total proportions of the component materials. These conclusions will hopefully be used as reference for FGM pipe designing and fabricating.

Journal ArticleDOI
Ismail Esen1
Abstract: In this study, an improved finite element method is presented which can be used to analyse the transverse and axial vibrations of the functionally graded material (FGM) beams in a thermal environment and exposed to a mass moving at variable speed. The motion equations of the FGM beam were obtained using first order shear deformation theory (FSDT). In these equations, the interaction terms of the mass inertia are derived from the exact differential of the displacement functions of the beam relative to the mass contact point. For various temperature loads (homogeneous, linear and non-linear), thermal stresses are converted to mechanical stresses and then the thermal rigidity matrix is combined with the stiffness matrix of the beam. After verification of the method, the novel findings of the interaction of the moving mass with the FGM beam in different ceramic and metallic compositions are presented for uniform, linear and non-linear thermal loads and the variable speed of the mass.

Journal ArticleDOI
TL;DR: In this paper, the buckling responses of functionally graded material (FGM) plate subjected to uniform, linear, and non-linear in-plane loads are investigated using trigonometric and exponential function.
Abstract: The paper investigates the buckling responses of functionally graded material (FGM) plate subjected to uniform, linear, and non-linear in-plane loads New nonlinear in-plane load models are proposed based on trigonometric and exponential function Non-dimensional critical buckling loads are evaluated using non-polynomial based higher order shear deformation theory Navier’s method, which assures minimum numerical error, is employed to get an accurate explicit solution The equilibrium conditions are determined utilizing the principle of virtual displacements and material property are graded in the thickness direction using simple Voigt model or exponential law The present formulation is accurate and efficient in analyzing the behavior of thin, thick and moderately thick FGM plate for buckling analysis It is found that with the help of displacement-buckling load curve, critical buckling load can be derived and maximum displacement due to the instability of inplane load can be obtained Also, the randomness in the values of transverse displacement due to inplane load increases as the extent of uniformity of the load on the plate is disturbed Furthermore, the parametric varying studies are performed to analyse the effect of span-to-thickness ratio, volume fraction exponent, aspect ratio, the shape parameter for non-uniform inplane load, and non-dimensional load parameter on the non-dimensional deflections, stresses, and critical buckling load for FGM plates

Journal ArticleDOI
TL;DR: In this article, the authors investigated the small and large amplitude free vibrations of a curved beam (arch) resting on a nonlinear elastic foundation and established the governing motion equations of the arch using a higher order arch theory.
Abstract: Current investigation deals with the small and large amplitude free vibrations of a curved beam (arch) resting on a nonlinear elastic foundation. The arch is made of a functionally graded material, where the properties are graded across the thickness. Uniform temperature elevation in the arch is also considered and material properties are assumed to be temperature dependent. The governing motion equations of the arch are established using a higher order arch theory which satisfies the traction free boundary conditions and the von Karman type of non-linearity. The governing equations of the arch are solved for the case of an immovable pinned arch using the two step perturbation technique. Closed form expressions are given to estimate the nonlinear frequencies of the arch as a function of the mid-span deflection. Numerical results of this study are validated for the case of flat FGM beams on elastic foundation. Afterwards, novel numerical results are given to explore the influences of power law index, elastic foundation coefficients, length to thickness ratio, length to radius ratio, and the temperature effects.

Journal ArticleDOI
TL;DR: In this article, the authors investigated the vibration and sound radiation of porous functionally graded material (FGM) plates with temperature gradient along the thickness, and the effects of key parameters including the boundary condition, volume fraction index, thermal environment, temperature dependence of material properties and porosity volume fraction on the structural and acoustic responses of the FGM plate are discussed in detail.

Journal ArticleDOI
TL;DR: In this article, the transverse vibration of rotary functionally graded size-dependent tapered Bernoulli-Euler nanobeam in thermal environment at low temperature has been investigated based on Eringen's nonlocal theory for cantilever and propped cantilevers boundary conditions.
Abstract: In this article, transverse vibration of rotary functionally graded size-dependent tapered Bernoulli–Euler nanobeam in thermal environment at low temperature has been investigated based on Eringen's nonlocal theory for cantilever and propped cantilever boundary conditions. Material properties of FG nanobeam are supposed to be temperature dependant and vary continuously along the thickness according to the power-law form. The axial force is also included in the model as the true spatial variation due to the rotation. The nonlocal equations of motion are derived through Hamilton's principle and they are solved by the differential quadrature method. Validations are done by comparing available literatures and obtained results, which reveal the accuracy of the applied method. The detailed mathematical derivations are presented and numerical investigations are performed while the emphasis is placed on investigating the effect of the several parameters, such as angular velocity, material distribution pro...

Journal ArticleDOI
TL;DR: In this paper, the elastic structural stability analysis of the pressurized thin-walled functionally graded material (FGM) arches under temperature variation field was studied and the total potential energy function of the pinned-pinned arch was expressed explicitly by employing the classical thinwalled arch theories and admissible radial displacement functions.
Abstract: This paper focuses on the elastic structural stability analysis of the pressurized thin-walled functionally graded material (FGM) arches under temperature variation field. The material properties are temperature-dependent and thermo-elastic. The total potential energy function of the pinned–pinned arch was expressed explicitly by employing the classical thin-walled arch theories and admissible radial displacement functions. By means of the variational principle, the expressions of the critical buckling pressure were obtained analytically and verified numerically by developing a two-dimensional (2D) simulated model. The pre- and post-buckling equilibrium paths were depicted to explore the maximum pressure (buckling pressure). The comparison showed that the numerical results were in excellent agreement with the analytical solutions for different subtended angles, volume fraction exponents and temperature variations. In the end, the effects of volume fraction exponent and temperature variation were examined on the critical buckling pressure, the bending moment, the hoop force, the hoop strain and stress, the hoop and radial displacement components through the whole arch.