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دسترسی آزاد مقاله
1 - The Nexus between Female Genital Mutilation and Child Marriage in Nigeria: A Cultural Inhibition to Achieving Sustainable Development Goals
Olukemi AdebolaThe world leaders agreed to make the world a better place by year 2030 through the Sustainable Development Goals and targets. This however cannot be achieved in Nigeria except we are proactive about some cultural practices that negatively affect the girl child. Child Ma چکیده کاملThe world leaders agreed to make the world a better place by year 2030 through the Sustainable Development Goals and targets. This however cannot be achieved in Nigeria except we are proactive about some cultural practices that negatively affect the girl child. Child Marriage and Female Genital Mutilation/Cutting (FGM/C) are two deep-rooted Harmful Traditional Practices (HTPs) that have prevailed in Nigeria for a long time. This paper discusses the recurring and prevalence patterns of Female Genital Mutilation/Cutting (FGM/C) in South West and South-East Nigeria and Child Marriage in Northern Nigeria as major obstacles to the achievement of some of the Sustainable Development Goals (SDGs). The Sustainable Development Goal 1: Ending all forms poverty; Goal 3: General health and wellbeing; Goal 4: Accessing quality education and; Goal 5: Gender equality and women empowerment are directly affected by these cultural practices. Except measures are taken to checkmate HTPs of this sort, women and girls optimum advancement and progress will continue to be hampered. پرونده مقاله -
دسترسی آزاد مقاله
2 - بهبود مقاومت به شوک حرارتی پوشش چند لایه سد حرارتی با ایجاد ساختار نانو در لایه سرامیکی فوقانی پوشش
حمید رضا حمید رضا مقدم علی داودی محمود اکبری باصریاین تحقیق جهت مقایسه رفتار شوک حرارتی دو نوع پوشش پنج لایه سد حرارتی انجام شد. زیرلایه این پوشش‌ها مشابه نمونه صنعتی، از جنس فولاد 17-4PH انتخاب گردید. نوع اول، یک پوشش پنج لایه معمولی با لایه زیرین CoNiCrAlY و لایه سرامیکی فوقانی YSZ است که سه لایه میانی آنها، شامل مخل چکیده کاملاین تحقیق جهت مقایسه رفتار شوک حرارتی دو نوع پوشش پنج لایه سد حرارتی انجام شد. زیرلایه این پوشش‌ها مشابه نمونه صنعتی، از جنس فولاد 17-4PH انتخاب گردید. نوع اول، یک پوشش پنج لایه معمولی با لایه زیرین CoNiCrAlY و لایه سرامیکی فوقانی YSZ است که سه لایه میانی آنها، شامل مخلوطی از پودر YSZ+CoNiCrAlY با نسبت‌های مشخص می‌باشد. در پوشش نوع دوم، لایه فوقانی YSZ به صورت نانوساختار و بقیه لایه‌ها کاملا مشابه نوع اول است. جهت مقایسه این پوشش‌ها با پوشش‌های متداول و کاربردی، نمونه‌هایی از پوشش سد حرارتی دو لایه نیز مورد آزمون قرار گرفتند. تمام این نمونه‌ها به روش پاشش پلاسما در اتمسفر هوا تهیه گردیدند. جهت انجام آزمون شوک حرارتی، نمونه‌ها در دمای °C ۹۵۰ به مدت پنج دقیقه قرار گرفته و سپس در آب °C 25-20 کوئنچ شدند. این عمل تا انهدام تمام نمونه‌ها ادامه یافت. معیار انهدام هر نمونه، جدایش حدود 20 درصد سطح پوشش در نظر گرفته شد. جهت ارزیابی ریزساختاری نمونه‌ها، از SEM و FESEM استفاده گردید. در نهایت مشاهده گردید که طول عمر شوک حرارتی پوشش FG-TBC پنج لایه، تقریبا 5/1 برابر طول عمر شوک حرارتی پوشش TBC دو لایه بوده و همچنین ایجاد ساختار نانو در لایه سرامیکی فوقانی پوشش FG-TBC پنج لایه، موجب افزایش طول عمر شوک حرارتی این پوشش در حدود 14% شده است. پرونده مقاله -
دسترسی آزاد مقاله
3 - Experimental and Numerical Analysis of Titanium/HA FGM for Dental Implantation
Sina Sazesh Aazam Ghassemi Reza Ebrahimi Mohammad KhodaeiFGM dental implants are a very good alternative with respect to homogenous implants. In this study by focusing on mechanical property as one of the most important factors in implant design, the static behaviour of Ti/Nanostructure HA (hydroxyapatite) FGM dental implant چکیده کاملFGM dental implants are a very good alternative with respect to homogenous implants. In this study by focusing on mechanical property as one of the most important factors in implant design, the static behaviour of Ti/Nanostructure HA (hydroxyapatite) FGM dental implant has been fabricated and investigated experimentally and numerically. At the first step, the nanostructure hydroxyapatite powders were synthesized by natural origin. At the second step, the initial powders were cold compacted in order to fabricate Ti/HA FGM samples for 4 different volume fraction exponents (N=1/3, 2/3, 1, 2). Then the compacted powders have been sintered using a vacuum furnace, in which compressive strength of each particular sample was finally assessed. A three-dimensional geometrical model of FGM dental implant system and surrounding bone was created by using the macro programming language in ANSYS software and then finite element analysis under static forces was performed. Finally the experimental results strength tests were compared with numerical solutions. According to the results, the FGM dental implants made of Ti/HA under static forces were sufficiently safe. As a result, FGM sample with volume fraction exponent of N=2/3 was chosen as the best sample. پرونده مقاله -
دسترسی آزاد مقاله
4 - Dynamic Response of FGM Plates Under Blast Load
reza azarafza puya pirali Ali Davar majid ghadimiThe present study investigates the deformation of FGM plates under blast load. Hamilton's principle is used to obtain the dynamic Equations. The two constituent phases, ceramic and metal, vary across the wall thickness according to a prescribed power law. Boundary condi چکیده کاملThe present study investigates the deformation of FGM plates under blast load. Hamilton's principle is used to obtain the dynamic Equations. The two constituent phases, ceramic and metal, vary across the wall thickness according to a prescribed power law. Boundary conditions are assumed to be Simply Supported (SS). The type of explosive loading considered is a free in-air spherical air burst and creates a spherical shock wave that travels radially outward in all directions. For the pressure time of the explosion loading, Friedlander’s exponential relation has been used. In order to determine the response analytically, the stress potential field function is considered. Using the Galerkin method, the final Equations are obtained as nonlinear and nonhomogeneous second-order differential Equations. The effect of temperature including thermal stress resultants and different parameters on the dynamic response have been investigated. Results have been compared with references and validated. Results showed that the amplitude of the center point deflection of the FGM plate is less than the pure metal plates when exposed to blast load, by increasing the volumetric index percentage of FGM, center point deflection is increased and in the FGM plates, deformation of symmetrical plates is smaller than the asymmetric plates. Also by applying the damping coefficient of the FGM plates, the amplitude of center point deflection is reduced, and by increasing the aspect ratio of the FGM plate, its center point deflection against explosion waves is reduced and by considering the effects of thermal resultant forces and moments, center point deflection is increased. پرونده مقاله -
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5 - Analysis of FGM Cylindrical Shell under Impact Loading of Explosion
reza azarafza puya pirali Ali JavadiDue to the increasing application of Functionally Graded Materials (FGM) shells, it seems necessary to investigate their behaviour under different loads. Therefore, in this paper, the dynamic response of functionally graded materials cylindrical shells under explosive l چکیده کاملDue to the increasing application of Functionally Graded Materials (FGM) shells, it seems necessary to investigate their behaviour under different loads. Therefore, in this paper, the dynamic response of functionally graded materials cylindrical shells under explosive load has been investigated with analytical and simulation methods. LS-DYNA software is used in the simulation method. In analytical solution, vibration of composite circular cylindrical shells is investigated based on the first-order deformation shell theory. The boundary conditions are assumed to be fully simply supported. The dynamic response of composite shells is studied under blast loading. The modal technique is used to develop the analytical solution of composite shell. The solution for the shell under the giving loading condition can be found using the convolution integral. Material properties are assumed to be graded in the thickness direction according to Reddy function. A FGM cylindrical shell is made up of a mixture of ceramic and metal. Results show that the effect of explosion is such that it has the greatest effect on the inner layer and with increasing thickness to the outside of the shell this effect decreases and when the maximum deflection occurs, the dynamic velocity is zero. Also, it was observed that with increasing length, the radial deflection increases due to increasing the distance from the support to the center of the shell. پرونده مقاله -
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6 - Evaluation of Critical Buckling Load in FG Plate using Analytical and Finite Elements Methods
Hossein Ahmadi Rashid AMIR GHIASVAND Maziar Mahdipour Jalilian Mahdi KazemiIn this paper, analytical and finite element solutions of mechanical buckling of a thick Functionally Graded (FG) plate have been investigated. Boundary conditions have been assumed as simply supported at all edges and three different loadings have been applied. In anal چکیده کاملIn this paper, analytical and finite element solutions of mechanical buckling of a thick Functionally Graded (FG) plate have been investigated. Boundary conditions have been assumed as simply supported at all edges and three different loadings have been applied. In analytical section the procedure of developing the critical buckling force by third order shear theory has been presented and then the stability Equations have been reduced from 5 to 2. In continue, the problem has been solved using numerical simulation by ABAQUS. To validate the FEM, results have been compared and validated with analytical solution. The results show that the bi-axial compression loading case with the loading ratio of R to one and R to zero are the most possible and most unlikely case in buckling occurrence, respectively. پرونده مقاله -
دسترسی آزاد مقاله
7 - Active Control of Sandwich Microbeams Vibration with FGM and Viscoelastic/ER Core
Amir Hossein Yousefi farhad kiani Esmaeil AbediThis study is devoted to analyse of free and forced vibrations and semi-active control vibrations of sandwich microbeam with Functionally Graded Materials (FGM) and viscoelastic/electrorheological (ER) core. The intended model is for top and bottom layers of functionall چکیده کاملThis study is devoted to analyse of free and forced vibrations and semi-active control vibrations of sandwich microbeam with Functionally Graded Materials (FGM) and viscoelastic/electrorheological (ER) core. The intended model is for top and bottom layers of functionally graded materials with power law and a core model for Viscoelastic materials with complex shear modulus. Hamilton principle is used to determine the governing Equations of motion on the sandwich microbeam based on the modified couple stress theory. Mesh less method of Radial Basis Functions (RBF) is used to calculate natural frequency and the loss factor. All the effects of length scale parameter, shear modulus and changes due to variation of the electric field on the natural frequency and loss factor have been drawn. Combination of RBF method and forward difference led to evaluation of forced vibration and deflection of microbeam for length scale parameters and different electric fields under the dynamic load have been calculated and drawn. The feedback effects are analyzed for vibration amplitudes of sandwich microbeam by using Linear Quadratic Gaussian (LQG) and optimal control method. At the end, the results are compared with papers for different viscoelastic models such as Kelvin model, Bingham plastic model and complex modulus. پرونده مقاله -
دسترسی آزاد مقاله
8 - Buckling Analysis of Functionally Graded Shallow Spherical Shells Under External Hydrostatic Pressure
M Hosseini F KaramiThe aim of this paper is to determine the critical buckling load for simply supported thin shallow spherical shells made of functionally graded material (FGM) subjected to uniform external pressure. A metal-ceramic functionally graded (FG) shell with a power law distrib چکیده کاملThe aim of this paper is to determine the critical buckling load for simply supported thin shallow spherical shells made of functionally graded material (FGM) subjected to uniform external pressure. A metal-ceramic functionally graded (FG) shell with a power law distribution for volume fraction is considered, where its properties vary gradually through the shell thickness direction from pure metal on the inner surface to pure ceramic on the outer surface. First, the total potential energy functional is obtained using the first-order shell theory of Love and Kirchhoff, Donnell-Mushtari-Vlasov kinematic equations and Hooke''''''''''''''''s Law. Then, equilibrium equations are derived through the minimization of the total potential energy functional by employing the Euler equations. The stability equations are derived by application of the adjacent - equilibrium criterion. As the nonlinear strain-displacement relations are employed, so the presented analysis is nonlinear with high accuracy. The Galerkin method is used to determine the critical buckling load. The present problem is also analyzed numerically by simulating it in Abaqus software. For validation, the present analytical results are compared with the present numerical results and with the known data in the literature. Also, the effects of some important geometrical and mechanical parameters on the hydrostatic buckling pressure are investigated. پرونده مقاله -
دسترسی آزاد مقاله
9 - Effect of Temperature Dependency on Thermoelastic Behavior of Rotating Variable Thickness FGM Cantilever Beam
M.M.H Mirzaei A Loghman M ArefiThermoelastic behavior of temperature-dependent (TD) and independent (TID) functionally graded variable thickness cantilever beam subjected to mechanical and thermal loadings is studied based on shear deformation theory using a semi-analytical method. Loading is compose چکیده کاملThermoelastic behavior of temperature-dependent (TD) and independent (TID) functionally graded variable thickness cantilever beam subjected to mechanical and thermal loadings is studied based on shear deformation theory using a semi-analytical method. Loading is composed of a transverse distributed force, a longitudinal distributed temperature field due to steady-state heat conduction from root to the tip surface of the beam and an inertia body force due to rotation. A successive relaxation (SR) method for solving temperature-dependent steady-state heat conduction equation is employed to obtain the accurate temperature field. The beam is made of functionally graded material (FGM) in which the mechanical and thermal properties are variable in longitudinal direction based on the volume fraction of constituent. Using first-order shear deformation theory, linear strain–displacement relations and Generalized Hooke’s law, a system of second order differential equation is obtained. Using division method, differential equations are solved for every division. As a result, longitudinal displacement, transverse displacement, and consequently longitudinal stress, shear stress and effective stress are investigated. The results are presented for temperature dependent and independent properties. It has been found that the temperature dependency of the material has a significant effect on temperature distribution, displacements and stresses. This model can be used for thermoelastic analysis of simple turbine blades. پرونده مقاله -
دسترسی آزاد مقاله
10 - Free Vibration and Transient Response of Heterogeneous Piezoelectric Sandwich Annular Plate Using Third-Order Shear Deformation Assumption
P Roodgar Saffari M Fakhraie M.A RoudbariBased on the third-order shear deformation theory (TSDT), this paper numerically investigates the natural frequencies and time response of three-layered annular plate with functionally graded materials (FGMs) sheet core and piezoelectric face sheets, under initial exter چکیده کاملBased on the third-order shear deformation theory (TSDT), this paper numerically investigates the natural frequencies and time response of three-layered annular plate with functionally graded materials (FGMs) sheet core and piezoelectric face sheets, under initial external electric voltage. The impressive material specifications of FGM core are assumed to vary continuously across the plate thickness utilizing a power law distribution. The equilibriumequations are obtained employing Hamilton’s method and then solved applying differential quadrature method (DQM) in conjunction with Newmark-β. Numerical studies are carried out to express the influences of the external electric voltage, aspect ratio, and material gradient on the variations of the natural frequencies and time response curves of FGM piezoelectric sandwich annular plate. It is precisely shown that these parameters have considerable effects on the free vibration and transient response. پرونده مقاله -
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11 - Size-Dependent Higher Order Thermo-Mechanical Vibration Analysis of Two Directional Functionally Graded Material Nanobeam
M Mahinzare S Amanpanah M GhadiriThis paper represented a numerical technique for discovering the vibrational behavior of a two-directional FGM (2-FGM) nanobeam exposed to thermal load for the first time. Mechanical attributes of two-directional FGM (2-FGM) nanobeam are changed along the thickness and چکیده کاملThis paper represented a numerical technique for discovering the vibrational behavior of a two-directional FGM (2-FGM) nanobeam exposed to thermal load for the first time. Mechanical attributes of two-directional FGM (2-FGM) nanobeam are changed along the thickness and length directions of nanobeam. The nonlocal Eringen parameter is taken into the nonlocal elasticity theory (NET). Uniform temperature rise (UTR), linear temperature rise (LTR), non-linear temperature rise (NLTR) and sinusoidal temperature rise (STR) during the thickness and length directions of nanobeam is analyzed. Third-order shear deformation theory (TSDT) is used to derive the governing equations of motion and associated boundary conditions of the two-directional FGM (2-FGM) nanobeam via Hamilton’s principle. The differential quadrature method (DQM) is employed to achieve the natural frequency of two-directional FGM (2-FGM) nanobeam. A parametric study is led to assess the efficacy of coefficients of two-directional FGM (2-FGM), Nonlocal parameter, FG power index, temperature changes, thermal rises loading and temperature rises on the non-dimensional natural frequencies of two-directional FGM (2-FGM) nanobeam. پرونده مقاله -
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12 - Dynamic Response of Bi-Directional Functionally Graded Materials (BDFGMs) Beams Rested on Visco-Pasternak Foundation Under Periodic Axial Force
A.A Ghorbanpour Arani S Niknejad A.A Abbasian AraniSince the temperature or stress distribution in some advanced machines such as modern aerospace shuttles and craft develops in two or three directions, the need for a new type of FGMs is felt whose properties vary in two or three directions. On the other hand, dynamic b چکیده کاملSince the temperature or stress distribution in some advanced machines such as modern aerospace shuttles and craft develops in two or three directions, the need for a new type of FGMs is felt whose properties vary in two or three directions. On the other hand, dynamic buckling behavior of structures is a complicated phenomenon which should be investigated through the response of equations of motion. In this paper, dynamic response of beams composed of bi-directional functionally graded materials (BDFGMs) rested on visco-Pasternak foundation under periodic axial force is investigated. Material properties of BDFGMs beam vary continuously in both the thickness and longitudinal directions based on the two types of analytical functions (e.g. exponential and power law distributions). Hamilton's principle is employed to derive the equations of motion of BDFGMs beam according to the Euler-Bernoulli and Timoshenko beam theories. Then, the generalized differential quadrature (GDQ) method in conjunction with the Bolotin method is used to solve the differential equations of motion under different boundary conditions. It is observed that a good agreement between the present work and the literature result. Various parametric investigations are performed for the effects of the gradient index, length-to-thickness ratio and viscoelastic foundation coefficients on the dynamic stability region of BDFGMs beam. The results show that the influence of gradient index of material properties along the thickness direction is greater than gradient index along the longitudinal direction on the dynamic stability of BDFGMs beam for both exponential and power law distributions. پرونده مقاله -
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13 - Elasticity Exact Solution for an FGM Cylindrical Shaft with Piezoelectric Layers Under the Saint-Venant Torsion by Using Prandtl’s Formulation
M. R Eslami M Jabbari A Eskandarzadeh SabetFunctionally graded materials (FGMs) belong to a noble family of composite material possess material properties varying gradually in a desired direction or orientation. In a past decade, functionally graded materials were remained in an interest of material investigator چکیده کاملFunctionally graded materials (FGMs) belong to a noble family of composite material possess material properties varying gradually in a desired direction or orientation. In a past decade, functionally graded materials were remained in an interest of material investigators due to its prominent features, and have extensively used in almost every discipline of engineering which in turn significantly increases the number of research publication of FGM. In this paper the exact elasticity solution for an FGM circular shaft with piezo layers is analysed. piezoelectric layers are homogeneous and the modulus of elasticity for FGM varies continuously with the form of an exponential function. The shear modulus of the non-homogeneous FGM shaft is a given function of the Prandtl’s stress function of considered circular shaft when its material is homogeneous. state equations are derived. The Prandtl’s stress function and electric displacement potential function satisfy all conditions. The shearing stresses, torsional rigidity, torsional function for FGM layer and shearing stresses, electric displacements, torsional rigidity, electrical torsional rigidity ,torsional and electrical potential functions for piezoelectric layers are obtained. Exact analytical solution for hollow circular cross-section presented. At the end some graphs and conclusions are given. پرونده مقاله -
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14 - Analysis of a Functionally Graded Finite Wedge Under Antiplane Deformation
A. R Shahani I ShakeriThe antiplane deformation of a wedge made of a functionally graded material (FGM) with finite radius has been investigated analytically in the present article. In relation to the boundary conditions imposed on the arc portion of the wedge, displacement or traction, two چکیده کاملThe antiplane deformation of a wedge made of a functionally graded material (FGM) with finite radius has been investigated analytically in the present article. In relation to the boundary conditions imposed on the arc portion of the wedge, displacement or traction, two problems have been studied. In each of the problems three various kinds of boundary conditions (traction-displacement, displacement-displacement and traction-traction) have been applied to the radial edges of the wedge. The governing differential equations have been solved by employing finite Fourier transforms and Green’s function method. The closed form solutions for stress and displacement distribution have been achieved for the whole domain. Explicit relations have been extracted for the order of stress singularity in all cases. These relations indicated the dependence of the order of stress singularity on the boundary conditions, material property and wedge angle. In fact, despite of an isotropic wedge, for which the order of stress singularity depends only the geometry of the wedge, in an FG wedge the order of stress singularity depends both the geometry as well as the material property. پرونده مقاله -
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15 - Fracture Analysis of Several Interface Cracks in an FG Half-Plane with a Homogeneous Coating under Mixed-Mode Transient Loading
R Bagheri M Ayatollahi S. M Hosseini A BagheriIn this paper, the mechanical fracture problem of a half-plane made of functionally graded material (FGM) with a coating of a homogeneous layer containing multiple interface cracks is investigated in order to determine the dynamic stress intensity factors (DSIFs) under چکیده کاملIn this paper, the mechanical fracture problem of a half-plane made of functionally graded material (FGM) with a coating of a homogeneous layer containing multiple interface cracks is investigated in order to determine the dynamic stress intensity factors (DSIFs) under transient in-plane loading. According to exponential law, the properties of functionally graded material change continuously along y-direction. Initially, integral transformations and dislocation of the Volterra type of climbing and sliding edges on the interface of a FG half-plane with a homogeneous coating leads to the numerical solution of a system with singular integral equations. These equations which have the Cauchy type-singularity are then obtained using the distributed dislocation technique (DDT). Using the inversion technique in the Laplace domain, the dislocation density on the crack faces is obtained which has led to the determination of the DSIFs. Finally, in order to show the accuracy and validity of this research, the final results in the form of graphs have been compared with other references and a very acceptable conformity has been observed. The influences of the FG parameter, coating thickness, crack length, the variation of time and the interaction between of cracks on the DSIFs are studied. پرونده مقاله -
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16 - Thermal Buckling Analysis of Temperature Dependent Porous FGM Mindlin Nano Circular Plate on Elastic Foundation
M. M Mohieddin GhomsheiIn the present work, the symmetric thermal buckling behavior of shear deformable heterogonous nano/micro circular porous plates resting on a two parameter foundation is studied. The material behavior of the nano plate is modeled by the modified couple stress theory. The چکیده کاملIn the present work, the symmetric thermal buckling behavior of shear deformable heterogonous nano/micro circular porous plates resting on a two parameter foundation is studied. The material behavior of the nano plate is modeled by the modified couple stress theory. The plate material properties assumed to be graded across the thickness direction according to a simple power law, and has a uniform porosity. Using Mindlin’s plate theory and the nonlinear von-Karman strain field and implementing the energy method, the plate stability equations together with the membrane equilibrium equation are derived and expressed in terms of the displacement field components. Then the nondimensionalized forms of the equations are discretized using differential quadrature method (DQM). The resulting eigenvalue problem is solved to evaluate the plate critical buckling temperature difference. Comparative studies are carried out. Also the influences of some important parameters including length scale factor, porosity factor and Winkler& Pasternak stiffness coefficients are investigated.. پرونده مقاله -
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17 - Analytical and Numerical Investigation of FGM Pressure Vessel Reinforced by Laminated Composite Materials
A.R Ghasemi A Kazemian M MoradiIn this research, the analytical and numerical investigation of a cylindrical shell made of functionally graded materials (FGMs) reinforced by laminated composite subjected to internal pressure is presented. Using the infinitesimal theory of elasticity, the analytical s چکیده کاملIn this research, the analytical and numerical investigation of a cylindrical shell made of functionally graded materials (FGMs) reinforced by laminated composite subjected to internal pressure is presented. Using the infinitesimal theory of elasticity, the analytical solution of stress and strain in vessels made of FGMs is studied first. It is assumed that the elasticity modulus follows a power law distribution in the thickness direction and Poisson's ratio considered to be constant for simplicity. The results of the finite element method using ABAQUS software for in-homogeneity constant in the range of -2 to 2 have been compared with the analytical results. The comparison represents good coincidence between analytical and numerical results and confirms the accuracy of stress and strain solutions presented for vessel made of FGMs. The stress and strain solutions in laminated composite vessels are then investigated. Finally, modeling of FGM vessel reinforced by composite laminates with different lay-up is taken into consideration. The obtained results demonstrate that in the cylindrical shell reinforced by laminated composites, the maximum stress is considerably less than the maximum stress in the pressure vessels made of just composites or FGMs. پرونده مقاله -
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18 - Free Vibration Analysis of Orthotropic FGM Cylinders by a Mesh-Free Method
R Moradi-Dastjerdi M ForoutanIn this paper, free vibration analysis of orthotropic functionally graded material (FGM) cylinders was carried out by a Mesh-Free method. In this analysis, moving least squares shape functions are used for approximation of displacement field in the weak form of equilibr چکیده کاملIn this paper, free vibration analysis of orthotropic functionally graded material (FGM) cylinders was carried out by a Mesh-Free method. In this analysis, moving least squares shape functions are used for approximation of displacement field in the weak form of equilibrium equation. Essential boundary conditions are imposed by transformation method. In this simulation, an axisymmetric model is used. The orthotropic FGM cylinders are assumed to be a mixture of two isotropic materials as fiber and matrix. The volume fraction of the fiber is changed in the radial direction. Consequently, mechanical properties of these cylinders are changed in the radial direction. Free vibration analysis of orthotropic FGM cylinders with any arbitrary combination of boundary conditions is possible by the proposed model. Natural frequencies obtained from the presented model are in good agreement with results of finite element simulation and other results from literature. Effects of various types of boundary conditions, geometrical parameters, and mechanical properties on the natural frequencies are studied. پرونده مقاله -
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19 - Creep Stress Redistribution Analysis of Thick-Walled FGM Spheres
S.M.A Aleayoub A LoghmanTime-dependent creep stress redistribution analysis of thick-walled FGM spheres subjected to an internal pressure and a uniform temperature field is investigated. The material creep and mechanical properties through the radial graded direction are assumed to obey the si چکیده کاملTime-dependent creep stress redistribution analysis of thick-walled FGM spheres subjected to an internal pressure and a uniform temperature field is investigated. The material creep and mechanical properties through the radial graded direction are assumed to obey the simple power-law variation throughout the thickness. Total strains are assumed to be the sum of elastic, thermal and creep strains. Creep strains are time temperature and stress dependent. Using equations of equilibrium, compatibility and stress-strain relations a differential equation, containing creep strains, for radial stress is obtained. Ignoring creep strains in this differential equation, a closed form solution for initial thermo-elastic stresses at zero time is presented. Initial thermo-elastic stresses are illustrated for different material properties. Using Prandtl-Reuss relation in conjunction with the above differential equation and the Norton’s law for the material uni-axial creep constitutive model, radial and tangential creep stress rates are obtained. These creep stress rates are containing integrals of effective stress and are evaluated numerically. Creep stress rates are plotted against dimensionless radius for different material properties. Using creep stress rates, stress redistributions are calculated iteratively using thermo-elastic stresses as initial values for stress redistributions. It has been found that radial stress redistributions are not significant for different material properties. However, major redistributions occur for tangential and effective stresses. پرونده مقاله -
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20 - Semi Analytical Analysis of FGM Thick-Walled Cylindrical Pressure Vessel with Longitudinal Variation of Elastic Modulus under Internal Pressure
M Shariati H Sadeghi M Ghannad H GharooniIn this paper, a numerical analysis of stresses and displacements in FGM thick-walled cylindrical pressure vessel under internal pressure has been presented. The elastic modulus is assumed to be varying along the longitude of the pressure vessel with an exponential func چکیده کاملIn this paper, a numerical analysis of stresses and displacements in FGM thick-walled cylindrical pressure vessel under internal pressure has been presented. The elastic modulus is assumed to be varying along the longitude of the pressure vessel with an exponential function continuously. The Poisson’s ratio is assumed to be constant. Whereas most of the previous studies about FGM thick-walled pressure vessels are on the basis of changing material properties along the radial direction, in this research, elastic analysis of cylindrical pressure vessel with exponential variations of elastic modulus along the longitudinal direction, under internal pressure, have been investigated. For the analysis of the vessel, the stiffness matrix of the cylindrical pressure vessel has been extracted by the usage of Galerkin Method and the numerical solution for axisymmetric cylindrical pressure vessel under internal pressure have been presented. Following that, displacements and stress distributions depending on inhomogeneity constant of FGM vessel along the longitudinal direction of elastic modulus, are illustrated and compared with those of the homogeneous case. The values which have been used in this study are arbitrary chosen to demonstrate the effect of inhomogeneity on displacements and stress distributions. Finally, the results are compared with the findings of finite element method (FEM). پرونده مقاله -
دسترسی آزاد مقاله
21 - Mechanical Behavior of a FGM Capacitive Micro-Beam Subjected to a Heat Source
I JafarSadeghi-Pournaki M.R Zamanzadeh R Shabani G RezazadehThis paper presents mechanical behavior of a functionally graded (FG) cantilever micro-beam subjected to a nonlinear electrostatic pressure and thermal moment considering effects of material length scale parameters. Material properties through the beam thickness directi چکیده کاملThis paper presents mechanical behavior of a functionally graded (FG) cantilever micro-beam subjected to a nonlinear electrostatic pressure and thermal moment considering effects of material length scale parameters. Material properties through the beam thickness direction are graded. The top surface of the micro-beam is made of pure metal and the bottom surface from a mixture of metal and ceramic. The material properties through the thickness direction follow the volume fraction of the constitutive materials in exponential function form. The governing nonlinear thermo-electro-mechanical differential equation based on Euler-Bernoulli beam theory assumptions is derived using modified couple stress theory (MCST) and is solved using the Galerkin based weighted residual method. The effects of the electrostatic pressure and temperature changes on the deflection and stability of the FGM micro-beam, having various ceramic constituent percents, are studied. The obtained results are compared with the results predicted by classic theory (CT) and for some cases are verified with those reported in the literature. پرونده مقاله -
دسترسی آزاد مقاله
22 - Thermal Stability of Thin Rectangular Plates with Variable Thickness Made of Functionally Graded Materials
M PouladvandIn this research, thermal buckling of thin rectangular plate made of Functionally Graded Materials (FGMs) with linear varying thickness is considered. Material properties are assumed to be graded in the thickness direction according to a simple power law distribution in چکیده کاملIn this research, thermal buckling of thin rectangular plate made of Functionally Graded Materials (FGMs) with linear varying thickness is considered. Material properties 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. The supporting condition of all edges of such a plate is simply supported. The equilibrium and stability equations of a FGM rectangular plate (FGRP) under thermal loads derived based on classical plate theory (CPT) via variational formulation, and are used to determine the pre-buckling forces and the governing differential equation of the plate. The buckling analysis of a functionally graded plate is conducted using; the uniform temperature rise, having temperature gradient through-the-thickness, and linear temperature variation in the thickness and closed-form solutions are obtained. The buckling load is defined in a weighted residual approach. In a special case the obtained results are compared by the results of functionally graded plates with uniform thickness. The influences of the plate thickness variation and the edge ratio on the critical loads are investigated. Finally, different plots indicating the variation of buckling load vs. different gradient exponent k, different geometries and loading conditions were obtained. پرونده مقاله -
دسترسی آزاد مقاله
23 - Generalized Differential Quadrature Method for Vibration Analysis of Cantilever Trapezoidal FG Thick Plate
K Torabi H AfshariThis paper presents a numerical solution for vibration analysis of a cantilever trapezoidal thick plate. The material of the plate is considered to be graded through the thickness from a metal surface to a ceramic one according to a power law function. Kinetic and strai چکیده کاملThis paper presents a numerical solution for vibration analysis of a cantilever trapezoidal thick plate. The material of the plate is considered to be graded through the thickness from a metal surface to a ceramic one according to a power law function. Kinetic and strain energies are derived based on the Reissner-Mindlin theory for thick plates and using Hamilton's principle, the governing equations and boundary conditions are derived in the Cartesian coordinates. A transformation of coordinates is used to convert the equations and boundary conditions from the original coordinate into a new computational coordinates. Generalized differential quadrature method (GDQM) is selected as a strong method and natural frequencies and corresponding modes are derived. The accuracy and convergence of the proposed solution are confirmed using results presented by other authors. Finally, the effect of the power law index, angles and thickness of the plate on the natural frequencies are investigated. پرونده مقاله -
دسترسی آزاد مقاله
24 - Calculation of Natural Frequencies of Bi-Layered Rotating Functionally Graded Cylindrical Shells
I Fakhari GolpayeganiIn this paper, an exact analytical solution for free vibration of rotating bi-layered cylindrical shell composed of two independent functionally graded layers was presented. The thicknesses of the shell layers were assumed to be equal and constant. The material properti چکیده کاملIn this paper, an exact analytical solution for free vibration of rotating bi-layered cylindrical shell composed of two independent functionally graded layers was presented. The thicknesses of the shell layers were assumed to be equal and constant. The material properties of the constituents of bi-layered FGM cylindrical shell were graded in the thickness direction of the layers of the shell according to a volume fraction power-law distribution. In order to derive the equations of motion, the Sanders’ thin shell theory and Rayleigh-Ritz method were used. Also the results were extracted by considering Coriolis, centrifugal and initial hoop tension effects. Effects of rotating speed, geometrical parameters, and material distribution in the two functionally graded layers of the shell, circumferential and longitudinal wave number on the forward and backward natural frequencies were investigated. A comparison of the results was made with those available in the literature for the validity and accuracy of the present methodology. پرونده مقاله -
دسترسی آزاد مقاله
25 - Displacements and Stresses in Pressurized Thick FGM Cylinders with Varying Properties of Power Function Based on HSDT
M Ghannad H GharooniUsing the infinitesimal theory of elasticity and analytical formulation, displacements and stresses based on the high-order shear deformation theory (HSDT) is presented for axisymmetric thick-walled cylinders made of functionally graded materials under internal and/or ex چکیده کاملUsing the infinitesimal theory of elasticity and analytical formulation, displacements and stresses based on the high-order shear deformation theory (HSDT) is presented for axisymmetric thick-walled cylinders made of functionally graded materials under internal and/or external uniform pressure. The material is assumed to be isotropic heterogeneous with constant Poisson’s ratio and radially varying elastic modulus continuously along the thickness with a power function. At first, general governing equations of the FGM thick cylinders are derived by assumptions of the high-order shear deformation theory. Following that, the set of non-homogenous linear differential equations with constant coefficients, for the cylinder under the generalized clamped-clamped conditions have been solved analytically and the effect of loading and inhomogeneity on the stresses and displacements have been investigated. The results are compared with the findings of both first-order shear deformation theory (FSDT) and finite element method (FEM). Finally, the effects of higher order approximations on the stresses and displacements have been studied. پرونده مقاله -
دسترسی آزاد مقاله
26 - Temperature Effects on Nonlinear Vibration of FGM Plates Coupled with Piezoelectric Actuators
F Ebrahimi A RastgooAn analytical solution for a sandwich circular FGM plate coupled with piezoelectric layers under one-dimension heat conduction is presented in this paper. A nonlinear static problem is solved first to determine the initial stress state and pre-vibration deformations. By چکیده کاملAn analytical solution for a sandwich circular FGM plate coupled with piezoelectric layers under one-dimension heat conduction is presented in this paper. A nonlinear static problem is solved first to determine the initial stress state and pre-vibration deformations. By adding an incremental dynamic state to the pre-vibration state, the differential equations are derived. The role of thermal environment and control effects on nonlinear static deflections and natural frequencies imposed by the piezoelectric actuators using high input voltages are investigated. The good agreement between the results of this paper and those of the finite element (FE) analyses validated the presented approach. The emphasis is placed on investigating the effect of varying the applied actuator voltage and thermal environment as well as gradient index of FG plate on the dynamics and control characteristics of the structure. پرونده مقاله -
دسترسی آزاد مقاله
27 - Effect of Temperature Changes on Dynamic Pull-in Phenomenon in a Functionally Graded Capacitive Micro-beam
B Mohammadi-Alasti G Rezazadeh M AbbasgholipourIn this paper, dynamic behavior of a functionally graded cantilever micro-beam and its pull-in instability, subjected to simultaneous effects of a thermal moment and nonlinear electrostatic pressure, has been studied. It has been assumed that the top surface is made of چکیده کاملIn this paper, dynamic behavior of a functionally graded cantilever micro-beam and its pull-in instability, subjected to simultaneous effects of a thermal moment and nonlinear electrostatic pressure, has been studied. It has been assumed that the top surface is made of pure metal and the bottom surface from a metal–ceramic mixture. The ceramic constituent percent of the bottom surface ranges from 0% to 100%. Along with the Volume Fractional Rule of material, an exponential function has been applied to represent the continuous gradation of the material properties through the micro-beam thickness. Attentions being paid to the ceramic constituent percent of the bottom surface, five different types of FGM micro-beams have been studied. Nonlinear integro-differential thermo-electro-mechanical equation based on Euler–Bernoulli beam theory has been derived. The governing equation in the static case has been solved using Step-by-Step Linearization Method and Finite Difference Method. Fixed points or equilibrium positions and singular points of the FGM micro-beam have been determined and shown in the state control space. In order to study stability of the fixed points, beam motion trajectories have been drawn, with different initial conditions, in the phase plane. In order to find the response of the micro-beam to a step DC voltage, the nonlinear equation of motion has been solved using Galerkin-based reduced-order model and time histories and phase portrait for different applied voltages and various primal temperatures have been illustrated. The effects of temperature change and electrostatic pressure on the deflection and stability of FGM micro-beams having various amounts of the ceramic constituent have been studied . پرونده مقاله -
دسترسی آزاد مقاله
28 - Static Analysis of Functionally Graded Annular Plate Resting on Elastic Foundation Subject to an Axisymmetric Transverse Load Based on the Three Dimensional Theory of Elasticity
A Behravan Rad A Alibeigloo S.S MalihiIn this paper, static analysis of functionally graded annular plate resting on elastic foundation with various boundary conditions is carried out by using a semi-‍analytical approach‍ (SSM‍-DQM). The differential governing equations are presented based on th چکیده کاملIn this paper, static analysis of functionally graded annular plate resting on elastic foundation with various boundary conditions is carried out by using a semi-‍analytical approach‍ (SSM‍-DQM). The differential governing equations are presented based on the three dimensional theory of elasticity. The plate is assumed isotropic at any point, while material properties to vary exponentially through the thickness direction and the Poisson’s ratio remain constant. The system of governing partial differential equations can be writhen as state equations by expanding the state variables and using the state space method (SSM) about thickness direction and applying the one dimensional differential quadrature method (DQM) along the radial direction. Interactions between the plate and two parameter elastic foundations are treated as boundary conditions. The stresses and displacements distributions are obtained by solving these state equations. In this study, the influences of the material property graded index, the elastic foundation coefficients (Winkler-Pasternak), the thickness to radius ratio, and edge supports effect on the bending behavior of the FGM annular plate are investigated and discussed in details. پرونده مقاله -
دسترسی آزاد مقاله
29 - Asymmetric Thermal Stresses of Hollow FGM Cylinders with Piezoelectric Internal and External Layers
M Jabbari M.B AghdamIn this paper ,the general solution of steady-state one dimensional asymmetric thermal stresses and electrical and mechanical displacements of a hollow cylinder made of functionally graded material and piezoelectric layers is developed .The material properties ,except t چکیده کاملIn this paper ,the general solution of steady-state one dimensional asymmetric thermal stresses and electrical and mechanical displacements of a hollow cylinder made of functionally graded material and piezoelectric layers is developed .The material properties ,except the Poisson's ration, are assumed to depend on the variable radius and they are expressed as power functions of radius. The temperature distribution is assumed to be a function of radius with general thermal and mechanical boundary conditions on the inside and outside surfaces. By using the separation of variables method and complex Fourier series, the Navier equations in term of displacements are derived and solved. پرونده مقاله -
دسترسی آزاد مقاله
30 - On the Analysis of FGM Beams: FEM with Innovative Element
M Zakeri A Modarakar Haghighi R AttarnejadThis paper aims at presenting a new efficient element for free vibration and instability analysis of Axially Functionally Graded Materials (FGMs) non-prismatic beams using Finite Element Method (FEM). Using concept of Basic Displacement Functions (BDFs), two- node eleme چکیده کاملThis paper aims at presenting a new efficient element for free vibration and instability analysis of Axially Functionally Graded Materials (FGMs) non-prismatic beams using Finite Element Method (FEM). Using concept of Basic Displacement Functions (BDFs), two- node element extends to three-node element for obtaining much more exact results using FEM. First, BDFs are introduced and computed using energy method such as unit-dummy load method. Afterward, new efficient shape functions are developed in terms of BDFs during the procedure based on the mechanical behavior of the element in which presented shape functions benefit generality and accuracy from stiffness and force method, respectively. Finally, deriving structural matrices of the beam with respect to new shape functions; free vibration and instability analysis of the FGM beam are studied using finite element method for all types of AFGM beams and the convergence of FEM has been studied. The results from both free vibration and instability analysis are in perfect agreement with those of previously published. پرونده مقاله -
دسترسی آزاد مقاله
31 - Effect of Exponentially-Varying Properties on Displacements and Stresses in Pressurized Functionally Graded Thick Spherical Shells with Using Iterative Technique
M Zamani Nejad A Rastgoo A HadiA semi-analytical iterative method as one of the newest analytical methods is used for the elastic analysis of thick-walled spherical pressure vessels made of functionally graded materials subjected to internal pressure. This method is accurate, fast and has a reasonabl چکیده کاملA semi-analytical iterative method as one of the newest analytical methods is used for the elastic analysis of thick-walled spherical pressure vessels made of functionally graded materials subjected to internal pressure. This method is accurate, fast and has a reasonable order of convergence. It is assumed that material properties except Poisson’s ratio are graded through the thickness direction of the sphere according to an exponential distribution. For different values of inhomogeneity constant, distributions of radial displacement, radial stress, circumferential stress, and von Mises equivalent stress, as a function of radial direction, are obtained. A numerical solution, using finite element method (FEM), is also presented. Good agreement was found between the semi-analytical results and those obtained through FEM. پرونده مقاله -
دسترسی آزاد مقاله
32 - Static and Free Vibration Analyses of Orthotropic FGM Plates Resting on Two-Parameter Elastic Foundation by a Mesh-Free Method
H Momeni-KhabisiIn this paper, static and free vibrations behaviors of the orthotropic functionally graded material (FGM) plates resting on the two-parameter elastic foundation are analyzed by the a mesh-free method based on the first order shear deformation plate theory (FSDT). The me چکیده کاملIn this paper, static and free vibrations behaviors of the orthotropic functionally graded material (FGM) plates resting on the two-parameter elastic foundation are analyzed by the a mesh-free method based on the first order shear deformation plate theory (FSDT). The mesh-free method is based on moving least squares (MLS) shape functions and essential boundary conditions are imposed by transfer function method. The orthotropic FGM plates are made of two orthotropic materials and their volume fractions are varied smoothly along the plate thickness. The convergence of the method is demonstrated and to validate the results, comparisons are made with finite element method (FEM) and the others available solutions for both homogeneous and FGM plates then numerical examples are provided to investigate the effects of material distributions, elastic foundation coefficients, geometrical dimensions, applied force and boundary conditions on the static and vibrational characteristics of the orthotropic FGM plates. پرونده مقاله -
دسترسی آزاد مقاله
33 - Mechanical Stresses in a Linear Plastic FGM Hollow and Solid Rotational Disk
M Jabbari A Hatefkia M ShokouhfarIn this paper, an analytical solution for computing the plastic & linear plastic stresses and critical angular velocity in a FGM hollow & solid rotating disk is developed. It has been assumed that the modulus of elasticity and yield strength were varying through چکیده کاملIn this paper, an analytical solution for computing the plastic & linear plastic stresses and critical angular velocity in a FGM hollow & solid rotating disk is developed. It has been assumed that the modulus of elasticity and yield strength were varying through thickness of the FGM material according to a power law relationship. The Poisson's ratio were considered constant throughout the thickness. In the analysis presented here the effect of non-homogeneity in FGM rotating disk was implemented by choosing a dimensionless parameter, named m, which could be assigned an arbitrary value affecting the stresses in the rotating disk. Distribution of stresses in radial and circumferential directions for FGM rotating disk under the influence of angular velocity were obtained. Graphs of variations of stress, critical angular velocity versus radius of the rotating disk were plotted. The direct method is used to solve the Navier equations. پرونده مقاله -
دسترسی آزاد مقاله
34 - Two-dimensional Axisymmetric Electromechanical Response of Piezoelectric, Functionally Graded and Layered Composite Cylinders
T Kant P DesaiA mixed semi-analytical cum numerical approach is presented in this paper which accounts for the coupled mechanical and electrical response of piezoelectric, functionally graded (FG) and layered composite hollow circular cylinders of finite length. Under axisymmetric me چکیده کاملA mixed semi-analytical cum numerical approach is presented in this paper which accounts for the coupled mechanical and electrical response of piezoelectric, functionally graded (FG) and layered composite hollow circular cylinders of finite length. Under axisymmetric mechanical and electrical loadings, the three-dimensional problem (3D) gets reduced to a two-dimensional (2D) plane strain problem of elasticity. The 2D problem is further simplified and reduced to a one-dimensional (1D) by assuming an analytical solution in longitudinal direction (z) in terms of Fourier series expansion which satisfies the simply (diaphragm) supported boundary conditions exactly at the two ends z = 0, l. Fundamental (basic) dependent variables are chosen in the radial direction (thickness coordinate) of the cylinder. The resulting mathematical model is cast in the form of first order simultaneous ordinary differential equations which are integrated through an effective numerical integration technique by first transforming the BVP into a set of initial value problems (IVPs). The cylinder is subjected to internal/external pressurized mechanical and an electrical loading. Finally, numerical results are obtained which govern the active and sensory response of piezoelectric and FG cylinders. Numerical results are compared for their accuracy with available results. New results of finite length cylinders are generated and presented for future reference. پرونده مقاله -
دسترسی آزاد مقاله
35 - Vibration Analysis of FG Nanoplate Based on Third-Order Shear Deformation Theory (TSDT) and Nonlocal Elasticity
M.M Najafizadeh M Raki P YousefiIn present study, the third-order shear deformation theory has been developed to investigate vibration analysis of FG Nano-plates based on Eringen nonlocal elasticity theory. The materials distribution regarding to the thickness of Nano-plate has been considered based o چکیده کاملIn present study, the third-order shear deformation theory has been developed to investigate vibration analysis of FG Nano-plates based on Eringen nonlocal elasticity theory. The materials distribution regarding to the thickness of Nano-plate has been considered based on two different models of power function and exponential function. All equations governing on the vibration of FG Nano-plate have been derived from Hamilton’s principle. It has been also obtained the analytical solution for natural frequencies and corresponding mode shapes of simply supported FG Nano-plates. In addition, the general form of stiffness and mass matrix elements has been expressed based on this theory. The effect of different parameters such as power and exponential indexes of targeted function , nonlocal parameter of Nano-plate, aspect ratio and thickness to length ratio of Nano-plate on non-dimensional natural frequencies of free vibration responses have been investigated. The obtained analytical results show an excellent agreement with other available solutions of previous studies. The formulation and analytical results obtained from proposed method can be used as a benchmark for further studies to develop this area of research. پرونده مقاله -
دسترسی آزاد مقاله
36 - Time-Dependent Hygro-Thermal Creep Analysis of Pressurized FGM Rotating Thick Cylindrical Shells Subjected to Uniform Magnetic Field
A Bakhshizadeh M Zamani Nejad M Davoudi KashkoliTime-dependent creep analysis is presented for the calculation of stresses and displacements of axisymmetric thick-walled cylindrical pressure vessels made of functionally graded material (FGM). For the purpose of time-dependent stress analysis in an FGM pressure vessel چکیده کاملTime-dependent creep analysis is presented for the calculation of stresses and displacements of axisymmetric thick-walled cylindrical pressure vessels made of functionally graded material (FGM). For the purpose of time-dependent stress analysis in an FGM pressure vessel, material creep behavior and the solutions of the stresses at a time equal to zero (i.e. the initial stress state) are needed. This corresponds to the solution of the problem considering linear elastic behavior of the material. Therefore, using equations of equilibrium, stress–strain and strain–displacement, a differential equation for displacement is obtained and subsequently the initial elastic stresses at a time equal to zero are calculated. Assuming that the Magneto-hygro-thermoelastic creep response of the material is governed by Norton’s law, using the rate form of constitutive differential equation, the displacement rate is obtained and then the stress rates are calculated. Once the stress rates are known, the stresses at any time are calculated iteratively. The analytical solution is obtained for the plane strain condition. The pressure, inner radius and outer radius are considered to be constant and the magnetic field is uniform. Material properties are considered as power law function of the radius of the cylinder and the poisson’s ratio as constant. Following this, profiles are plotted for different values of material exponent for the radial, circumferential and effective stresses as a function of radial direction and time. The in-homogeneity exponent have significant influence on the distributions of the creep stresses. پرونده مقاله -
دسترسی آزاد مقاله
37 - Mechanical Stresses in a Linear Plastic FGM Hollow Cylinder Due to Non-Axisymmetric Loads
M Shokouhfar M JabbariIn this paper, an analytical solution for computing the linear plastic stresses and critical pressure in a FGM hollow cylinder under the internal pressure due to non-Axisymmetric Loads is developed. It has been assumed that the modulus of elasticity was varying through چکیده کاملIn this paper, an analytical solution for computing the linear plastic stresses and critical pressure in a FGM hollow cylinder under the internal pressure due to non-Axisymmetric Loads is developed. It has been assumed that the modulus of elasticity was varying through thickness of the FGM material according to a power law relationship. The Poisson's ratio was considered constant throughout the thickness. The general form of mechanical boundary conditions is considered on the inside surfaces. In the analysis presented here the effect of non-homogeneity in FGM cylinder was implemented by choosing a dimensionless parameter, named m, which could be assigned an arbitrary value affecting the stresses in the cylinder. Distribution of stresses in radial, circumferential and shear directions for FGM cylinders under the influence of internal pressure were obtained. Graphs of variations of stress versus radius of the cylinder were plotted. The direct method is used to solve the Navier equations. پرونده مقاله -
دسترسی آزاد مقاله
38 - Non-Linear Analysis of Asymmetrical Eccentrically Stiffened FGM Cylindrical Shells with Non-Linear Elastic Foundation
A.R Shaterzadeh K ForoutanIn this paper, semi-analytical method for asymmetrical eccentrically stiffened FGM cylindrical shells under external pressure and surrounded by a linear and non-linear elastic foundation is presented. The proposed linear model is based on two parameter elastic foundatio چکیده کاملIn this paper, semi-analytical method for asymmetrical eccentrically stiffened FGM cylindrical shells under external pressure and surrounded by a linear and non-linear elastic foundation is presented. The proposed linear model is based on two parameter elastic foundation Winkler and Pasternak. According to the von Karman nonlinear equations and the classical plate theory of shells, strain-displacement relations are obtained. The smeared stiffeners technique and Galerkin method, used for solving nonlinear problem. To finding the nonlinear dynamic response of fourth order Runge-Kutta method is used. The effect of parameters asymmetrical eccentrically stiffened on the nonlinear dynamic buckling response of FGM cylindrical shells have been investigated. پرونده مقاله -
دسترسی آزاد مقاله
39 - Free Axisymmetric Bending Vibration Analysis of two Directional FGM Circular Nano-plate on the Elastic Foundation
M Zarei Gh RahimiIn the following paper, free vibration analysis of two directional FGM circular nano-plate on the elastic medium is investigated. The elastic modulus of plate varies in both radial and thickness directions. Eringen’s theory was employed to the analysis of circular چکیده کاملIn the following paper, free vibration analysis of two directional FGM circular nano-plate on the elastic medium is investigated. The elastic modulus of plate varies in both radial and thickness directions. Eringen’s theory was employed to the analysis of circular nano-plate with variation in material properties. Simultaneous variations of the material properties in the radial and transverse directions are described by a general function. Ritz functions were utilized to obtain the frequency equations for simply supported and clamped boundary. Differential transform method also used to develop a semi-analytical solution the size-dependent natural frequencies of non-homogenous nano-plates. Both methods reported good results. The validity of solutions was performed by comparing present results with themselves and those of the literature for both classical plate and nano-plate. Effect of non-homogeneity on the nonlocal parameter, geometries, boundary conditions and elastic foundation parameters is examined the paper treats some interesting problems, for the first time. پرونده مقاله -
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40 - تحلیل ارتعاشات آزاد تیر تیموشینکو ساخته شده از مواد تابعی دو بعدی
محمد رحیم ترشیزیان عبدالحسین اخوت پوردر این تحقیق ارتعاشات آزاد یک تیر از جنس ماده تابعی دو بعدی با در نظر گرفتن تئوری تیر تیموشینکو بررسی شده است. تغییرات خواص مواد در دو جهت ضخامت و طول تیر به صورت تابع نمائی فرض شده است. معادلات حرکت با استفاده از اصل همیلتون بدست آمده که در آن اثر اینرسی های عمودی و دو چکیده کاملدر این تحقیق ارتعاشات آزاد یک تیر از جنس ماده تابعی دو بعدی با در نظر گرفتن تئوری تیر تیموشینکو بررسی شده است. تغییرات خواص مواد در دو جهت ضخامت و طول تیر به صورت تابع نمائی فرض شده است. معادلات حرکت با استفاده از اصل همیلتون بدست آمده که در آن اثر اینرسی های عمودی و دورانی نیز در نظر گرفته شده است. حل معادلات حرکت از روش لوی با رهیافتی از روش فضای حالت انجام گرفته و فرکانس های طبیعی تیر محاسبه شده اند. اثر تغییرات نسبت طول به ضخامت تیر، پارامتر های غیر همگونی ماده و شرایط مرزی، بر روی فرکانس های طبیعی تیر بررسی گردیده است. نتایج نشان می دهد، با افزایش نسبت طول به ضخامت تیر فرکانس های طبیعی افزایش می یابد و همچنین مقدار فرکانس های طبیعی برای تیر از ماده تابعی دو بعدی در شرایط یکسان بیشتر از مقدار آن در تیر از ماده تابعی یک بعدی می باشد. پرونده مقاله -
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41 - Free Vibration Analysis of Sandwich Plates with FGM Face Sheets and Temperature-Dependent Properties of the Core Materials
Y. MohammadiIn this paper, the free vibration of sandwich plates with power-law FGM face sheets in various thermal environments is performed by high-order sandwich plate theory. The material properties of the core, such as Young’s modulus, density, thermal expansion coefficie چکیده کاملIn this paper, the free vibration of sandwich plates with power-law FGM face sheets in various thermal environments is performed by high-order sandwich plate theory. The material properties of the core, such as Young’s modulus, density, thermal expansion coefficient and Poisson’s ratio, are assumed to be temperature dependent by nonlinear function of temperature [1]. The material properties of the FGM face sheets are assumed to vary continuously through the thickness according to a power law distribution in terms of volume fractions of the constituents [2]. The governing equations of motion in free natural vibration are derived using Hamilton’s principle [3]. A new approach is used to reduce the equations of motion from twenty three equations to eleven equations and then solve them. The new solution approach consists of isolating six of the unknowns in the displacements of the face sheets using the compatibility equations, followed by isolating the additional six Lagrange multipliers using the equations of the face sheets, finally, the isolated unknowns are substituted into the eleven equations of the core. Both un-symmetric and symmetric sandwich plates are considered in this analysis. Good agreement is found between theoretical predictions of the fundamental frequency parameters and the results obtained from other references for simply supported sandwich plates with functionally graded face sheets. The results show that the fundamental frequency parameters (ω ̅ ) increases by increasing the volume fraction index (κ). Also, the effect of temperature on the value of fundamental frequency parameters decreases with increases in the FGM face sheets thickness. The results also revealed that as the side-to-thickness ratio (b⁄h), the core-to-face sheet thickness ratio (h_c⁄h_t ) and temperature changes, have a significant effect on the fundamental frequency parameters. پرونده مقاله -
دسترسی آزاد مقاله
42 - Investigation of Influence External Pressures on Vibration of Thin-Walled Cylindrical Shell Supported Composed of Functionally Graded Materials
Mohammad Reza IsvandzibaeiThis paper presents the study on influence external pressures on vibration of functionally graded materials thin-walled cylindrical shell supported. The functionally graded materials (FGMs) properties are graded in the thickness direction of the shell. FGMs are advanced چکیده کاملThis paper presents the study on influence external pressures on vibration of functionally graded materials thin-walled cylindrical shell supported. The functionally graded materials (FGMs) properties are graded in the thickness direction of the shell. FGMs are advanced composite materials, consisting of different types of materials, in which the properties shift continuously from one material on the one side to another material on the other side with a specific gradient. The FGM cylindrical shell supported equations with external pressure are established based on classical shell theory with beam functions as axial modal function. The governing equations of motion were employed, using energy functional and by applying the Ritz method. The boundary conditions represented by end conditions of the FGM structure which are sliding-sliding, clamped-free and clamped-simply supported being considered. This problem was solved with computer programming using MAPLE package. Comparison results are carried out to verify the validity with published papers. The influence of the external pressures, loop support and effect of the different boundary conditions on natural frequencies of FGM thin-walled cylindrical shell are studied. پرونده مقاله -
دسترسی آزاد مقاله
43 - Effect of Material Gradient on Stresses of FGM Rotating Thick-Walled Cylindrical Pressure Vessel with Longitudinal Variation of Properties under Non-uniform Internal and External Pressure
Mehdi Jabbari Mohammad Zamani Nejad Mehdi GhannadThe present paper provides a semi-analytical solution to obtain the displacements and stresses in a functionally graded material (FGM) rotating thick cylindrical shell with clamped ends under non-uniform pressure. Material properties of cylinder are assumed to change al چکیده کاملThe present paper provides a semi-analytical solution to obtain the displacements and stresses in a functionally graded material (FGM) rotating thick cylindrical shell with clamped ends under non-uniform pressure. Material properties of cylinder are assumed to change along the axial direction according to a power law form. It is also assumed that the Poisson’s ratio is constant. Given the existence of shear stress in the thick cylindrical shell due to material and pressure changes along the axial direction, the governing equations are obtained based on first-order shear deformation theory (FSDT). These equations are in the form of a set of general differential equations with variable coefficients. Given that the FG cylinder is divided into n homogenous disks, n sets of differential equations with constant coefficients are obtained. The solution of this set of equations, applying the boundary conditions and continuity conditions between the layers, yields displacements and stresses. The problem was also solved, using the finite element method (FEM), the results of which were compared with those of the multi-layered method (MLM). Finally, some numerical results are presented to study the effects of applied pressure, non-homogeneity index, and power law index of FGM on the mechanical behavior of the cylindrical shell. پرونده مقاله -
دسترسی آزاد مقاله
44 - Influence of Power Law Distribution with Pressure on the Frequencies of Supported Functionally Graded Material Cylindrical Shell with C-SL and F-SS Boundary Conditions
Mohammad Reza IsvandzibaeiIn this paper, influence power-law distribution with pressure on frequencies of the supported functionally graded cylindrical shell is studied. This shell is constructed from a functionally graded material (FGM) with two constituent materials. FGMs are graded through th چکیده کاملIn this paper, influence power-law distribution with pressure on frequencies of the supported functionally graded cylindrical shell is studied. This shell is constructed from a functionally graded material (FGM) with two constituent materials. FGMs are graded through the thickness direction, from one surface of the shell to the next. The supported FGM shell equations are created based on FSDT. The governing equations of the movement were utilized by the Ritz method. The boundary conditions are clamp-sliding and free-simply support. The influence of the various values of the power-law distribution with pressure supported and different conditions on the frequencies characteristics are studied. This study shows that the frequencies decreased with the increase in the amounts of the power-law distribution with pressure. Thus, the constituent power-law distribution with pressure effects on the frequencies. The results show the frequencies with different power-law distribution under pressures are various for different conditions. پرونده مقاله -
دسترسی آزاد مقاله
45 - Free Vibration Analysis of Sandwich Beams with FG Face Sheets Based on the High Order Sandwich Beam Theory
Mohsen Rahmani Sajjad Dehghanpour Ali BarootihaIn this paper, the vibration behavior of the sandwich beams with functionally graded face-sheets is investigated based on the high order sandwich beam theory.The properties of the FGM are varied gradually across the thickness of the structures in accordant with the powe چکیده کاملIn this paper, the vibration behavior of the sandwich beams with functionally graded face-sheets is investigated based on the high order sandwich beam theory.The properties of the FGM are varied gradually across the thickness of the structures in accordant with the power-law rule. First-order shear deformation theory and polynomial patterns are used to model the displacements of the face-sheets and the core, respectively. The governing equations of the motion are obtained based on Hamilton’s energy principle and solved by a Galerkin method. An algebraic method is used to reduce the number of equations. Boundary conditions are considered as simply supported and clamped.The effect of the power-law index and geometrical variations are surveyed on the fundamental frequency parameter for different sandwich beams in some numerical examples. In order to verify the results of the present study, they are compared with special cases of the literature. پرونده مقاله -
دسترسی آزاد مقاله
46 - Effect of Different FGM Models on Creep Analysis of Thick-walled Cylindrical Pressure Vessel
Fakher Abdolkhani Mohammad Hashemian Farshid Aghadavoudi Nabard HabibiThick-walled cylindrical vessels are used widely in petrochemical and power plants. New additive manufacturing technology has made it possible to make FGMs. This research studies the creep analysis in the cylindrical FGM pressure vessel by considering three models and y چکیده کاملThick-walled cylindrical vessels are used widely in petrochemical and power plants. New additive manufacturing technology has made it possible to make FGMs. This research studies the creep analysis in the cylindrical FGM pressure vessel by considering three models and yield criteria. Also, the governing equations were extracted by considering the FGM models, and for determining creep stresses, the partial differential equations, were solved. Norton's equation is used to determine creep strain rates. The advantage of the exponential model is that in the inner radius for all n radial and circumferential creep strains rates have a constant value that is maintained by increasing the internal pressure up to 400 MPa. The graphs are smooth, and their values tend to zero in the outer radius. The changes of creep strain rate in terms of n in different internal pressures for the exponential model in the inner radius of the vessel show that increasing n from -4 to 0, these parameters have a reduction to the form of an exponential function, and the slope of the graph has the highest value at 360 MPa. پرونده مقاله -
دسترسی آزاد مقاله
47 - Nonlinear Buckling Analysis of Different Types of Porous FG Sandwich Beams with Temperature-Dependent
Mohsen Rahmani Younes Mohammadi Mahdi AbtahiIn this paper, the nonlinear buckling behavior of two types of functionally graded sandwich beams was studied using a high-order sandwich beam theory. Type I consists of functionally graded layers coating a homogeneous core, while type II features an FG core covered by چکیده کاملIn this paper, the nonlinear buckling behavior of two types of functionally graded sandwich beams was studied using a high-order sandwich beam theory. Type I consists of functionally graded layers coating a homogeneous core, while type II features an FG core covered by homogeneous face sheets. All materials are considered temperature dependent, with FGM properties modified through even and uneven porosity distributions modeled by a power law rule. The sandwich beam theory was adjusted to account for nonlinear Lagrange strains, thermal stresses of the face sheets, in-plane strain, and the transverse flexibility of the core. The governing equations were derived from the minimum potential energy principle, and a Galerkin method was employed to solve them for simply supported and clamped boundary conditions. Comparisons with existing literature demonstrate good agreement. The resultes showed that critical load parameter decreases with increasing temperature, power law index, length-to-thickness ratio, thickness, and porosity volume fraction in both distributions, but increases with the wave number. Additionally, the stability of type II sandwich beams surpasses that of type I in high-temperature conditions. پرونده مقاله -
دسترسی آزاد مقاله
48 - یک فیلتر Gm-C قابل تنظیم ولتاژ پایین و توان پایین برای کاربردهای بی‌سیم
امیر باغی رهین ضیاء‌الدین دائی کوزه کنانیدر این مقاله، یک تقویت کننده ترارسانایی عملیاتی (OTA) ولتاژ پایین و توان پایین با استفاده از ترانزیستور FGMOS پیشنهاد شده است. در OTA پیشنهادی در تکنولوژی TSMC 0.18 µm CMOS با ولتاژ تغذیه یک ولت و توان مصرفی ماکزیمم 40 µW، محدوده تنظیم نسبی 50 برابر به دست م چکیده کاملدر این مقاله، یک تقویت کننده ترارسانایی عملیاتی (OTA) ولتاژ پایین و توان پایین با استفاده از ترانزیستور FGMOS پیشنهاد شده است. در OTA پیشنهادی در تکنولوژی TSMC 0.18 µm CMOS با ولتاژ تغذیه یک ولت و توان مصرفی ماکزیمم 40 µW، محدوده تنظیم نسبی 50 برابر به دست می‌آید. نتایج شبیه‌سازی تقویت‌کننده پیشنهادی، بهره حلقه باز 30.2 dB و فرکانس بهره واحد 942 MHz را نشان می‌دهند. در مقایسه با کارهای قبلی، تقویت کننده پیشنهادی، با ولتاژ تغذیه کمتر، عملکرد فرکانسی بهتر، سوئینگ ولتاژ خروجی بالاتر، خطینگی بهتر و توان مصرفی کمتری را عرضه می‌کند. OTA پیشنهادی در ساختار یک فیلتر "G" _"m" "-C" مرتبه دوم به کار گرفته شده و محدوده تنظیم خوب از 100 kHz تا 5.6 MHz به دست آمد که مشخصات بی‌سیم Bluetooth (فرکانس 650 kHz)، CDMA2000 (فرکانس 700 kHz) و Wideband CDMA (فرکانس 2.2 MHz) را به خوبی پوشش می‌دهد. مساحت اشغال شده سیلیکون برای فیلتر طراحی شده برابر 192μm×535μm می‌باشد. پرونده مقاله -
دسترسی آزاد مقاله
49 - Torsion of cylindrically poroelasic circular shaft with radial inhomogeneity .some exact solutions for extruder
mohammad farid khansanami Faranak KhansanamiTorsion of elastic and poroelastic circular shaft of radially inhomogeneous, cylindrically orthotropic materials is studied with emphasis on the end effects example for extruder. To examine the conjecture of Saint-Venant’s torsion, we consider torsion of circular s چکیده کاملTorsion of elastic and poroelastic circular shaft of radially inhomogeneous, cylindrically orthotropic materials is studied with emphasis on the end effects example for extruder. To examine the conjecture of Saint-Venant’s torsion, we consider torsion of circular shaft with one end fixed and the other end free on which tractions that results in a pure torque are prescribed arbitrarily over the free end surface. Exact solutions that satisfy the prescribed boundary conditions point by point over the entire boundary surfaces are derived in a unified manner for cylindrically orthotropic shafts with or without radial inhomogeneity and for their coun- terparts of Saint-Venant’s torsion. Stress diffusion due to the end effect is examined in the light of the exact solutions.The present study enables us to assess Saint-Venant’s principle as applied to anisotropic, non-homogeneous poroelastic bodies in general and to evaluate the stress diffusion in torsion of radially inhomogeneous, cylindrically orthotropic cylinders in particular. The following conclusions can be drawn from the analysis. پرونده مقاله -
دسترسی آزاد مقاله
50 - Torsion of cylindrically poroelasic circular shaft with radial inhomogeneity .some exact solutions for extruder
محمد فرید خان سمنی فرانک خان سمنیTorsion of elastic and poroelastic circular shaft of radially inhomogeneous, cylindrically orthotropic materials is studied with emphasis on the end effects example for extruder. To examine the conjecture of Saint-Venant’s torsion, we consider torsion of circular s چکیده کاملTorsion of elastic and poroelastic circular shaft of radially inhomogeneous, cylindrically orthotropic materials is studied with emphasis on the end effects example for extruder. To examine the conjecture of Saint-Venant’s torsion, we consider torsion of circular shaft with one end fixed and the other end free on which tractions that results in a pure torque are prescribed arbitrarily over the free end surface. Exact solutions that satisfy the prescribed boundary conditions point by point over the entire boundary surfaces are derived in a unified manner for cylindrically orthotropic shafts with or without radial inhomogeneity and for their coun- terparts of Saint-Venant’s torsion. Stress diffusion due to the end effect is examined in the light of the exact solutions.The present study enables us to assess Saint-Venant’s principle as applied to anisotropic, non-homogeneous poroelastic bodies in general and to evaluate the stress diffusion in torsion of radially inhomogeneous, cylindrically orthotropic cylinders in particular. The following conclusions can be drawn from the analysis پرونده مقاله -
دسترسی آزاد مقاله
51 - Fracture analysis of multiple axisymmetric interfacial cracks in an FGM Coated orthotropic layer
Behrooz MomeniBased on the distributed dislocation technique, an analytical solution for the orthotropic layer with functionally graded material (FGM) orthotropic coating containing multiple axisymmetric interfacial cracks subjected to torsional loading is investigated. It is assumed چکیده کاملBased on the distributed dislocation technique, an analytical solution for the orthotropic layer with functionally graded material (FGM) orthotropic coating containing multiple axisymmetric interfacial cracks subjected to torsional loading is investigated. It is assumed that the material properties of the FGM orthotropic coating vary power-law form along the thickness of the layer. At first, by using the Hankel transform, the solution for Somigliana type rotational ring dislocation in the layer and its coating is obtained. Then, the dislocation solution is used to derive a set of singular integral equations for a system of coaxial axisymmetric interface cracks, including penny-shaped and annular cracks. cracks with Cauchy type kernel. The integral equations are of Cauchy singular type, which are solved by Erdogan’s collocation method for dislocation density on the surface of interfacial crack and the results are used to determine stress intensity factors (SIFs) for axisymmetric interface cracks. Finally, several examples are provided to study the effects of the non-homogeneity constant, orthotropy parameter and thickness of FGM coating on the SIFs for interfacial cracks.. The effects of the non-homogeneity constant, orthotropy parameter and thickness of FGM coating as well as the interaction of multiple interfacial cracks on the SIFs are investigated. The results reveal that the value of the SIFs decreases with increasing the non-homogeneity parameter, orthotropy and thickness of FGM coating. The SIFs for inner tips of annular interface crack are larger than the outer tips. پرونده مقاله -
دسترسی آزاد مقاله
52 - Dynamic stability analysis of functionally graded Euler-Bernoulli nanobeams under a sequence of moving nanoparticle based on nonlocal elasticity theory
Rahman Khanahmadi Mohammad Hashemian Mostafa PirmoradianThis study investigates the dynamic stability of the Euler-Bernoulli functionally graded (FGM) nanobeam based on the nonlocal elasticity theory while considering surface effects. Nanoparticles pass over nanobeam sequentially with a constant velocity, and the nanoparticl چکیده کاملThis study investigates the dynamic stability of the Euler-Bernoulli functionally graded (FGM) nanobeam based on the nonlocal elasticity theory while considering surface effects. Nanoparticles pass over nanobeam sequentially with a constant velocity, and the nanoparticle inertia is also considered. A thermal gradient with constant temperature changes is applied to this nanobeam. The functionally graded nanobeam properties, including Young’s modulus, density, surface residual stress, and surface modulus are taken by the power law. The classical equations of motion are obtained by applying the Hamilton’s principle according to the energy method. The governing equations are extracted using nonlocal elasticity theory, and the surface effects are taken by Gurtin-Murdoch theory. The dynamic stability graphs will be presented on nanoparticle mass-velocity coordinates. This article investigated the small scale effect parameter, temperature changes, Pasternak environment shearing and elastic constants, and the volume fraction parameter in power law. The results show that increasing Pasternak foundation constants increase the functionally graded nanobeam stability, and increasing small scale parameter reduces its stability. Increasing nanobeam temperature shifts the functionally graded stability region of nanobeam towards faster nanoparticle velocity, which indicates a higher dynamic stability for the nanobeam. پرونده مقاله -
دسترسی آزاد مقاله
53 - Frequency responses analysis of clamped-free sandwich beams with porous FG face sheets
Mohsen RahmaniIn this paper, the frequency responses analysis of the sandwich beams with functionally graded face sheets and homogeneous core is investigated based on the high order sandwich beam theory. All materials are temperature dependent and the functionally graded materials pr چکیده کاملIn this paper, the frequency responses analysis of the sandwich beams with functionally graded face sheets and homogeneous core is investigated based on the high order sandwich beam theory. All materials are temperature dependent and the functionally graded materials properties are varied gradually by a power law rule which is modified by considering the even and uneven porosity distributions. The nonlinear Lagrange strain and the thermal stresses of the face sheets and in-plane strain and transverse flexibility of the core are considered. Hamilton’s principle and Galerkin method are used to obtain and solve the equations for the clamped-free boundary condition. To verify the results of this study, they compared with special cases of the literatures. Based on the numerical results, it is concluded that by increasing the temperature, power law index, length, thickness, porosity volume fraction the fundamental frequency parameter decreases and increasing the wave number causes the frequency increases. پرونده مقاله -
دسترسی آزاد مقاله
54 - Vibration Suppression of Smart FGM Cylindrical Shells Using Magnetostrictive Layers
منصور درویزه رضا انصاری ابوالفضل درویزه رضا رجبیه فردIn the present work, FGM shells integrated with magnetostrictive layers acting as distributed sensors and actuators are modeled to control vibration attenuation of FGM shells with simply supported boundaryconditions. To achieve a mechanism for actively control of the os چکیده کاملIn the present work, FGM shells integrated with magnetostrictive layers acting as distributed sensors and actuators are modeled to control vibration attenuation of FGM shells with simply supported boundaryconditions. To achieve a mechanism for actively control of the oscillation amplitude of the integrated structure, a negative velocity proportional feedback control law is implemented in the study. Theoretical formulation is based on the first order shear deformation shell theory, taking into consideration transverse shear deformation and rotary inertia effects. Material properties are assumed to be temperature-dependent and graded in the thickness direction according to different volume fraction functions. A FGM cylindrical shell made up of a mixture of ceramic and metal is considered. The magnetostrictive layers are also considered to be made of Terfenol-D. The influence of vibration attenuation characteristics of magnetostrictive layers, the location of these layers and control parameters on vibration suppression is investigated. پرونده مقاله -
دسترسی آزاد مقاله
55 - Applying Differential Transform Method on the Effect of the Elastic Foundation on the out - Plane Displacement of the Functionally Graded Circular Plates
سمیه عباسی فاطمه فرهت نیا سعید رسولی جزیIn this paper, the effect of elastic foundation on the out of plane displacement of functionally graded circular plates using differential transform method is presented. Differential transform method is a semi-analytical-numerical solution technique that is capable to s چکیده کاملIn this paper, the effect of elastic foundation on the out of plane displacement of functionally graded circular plates using differential transform method is presented. Differential transform method is a semi-analytical-numerical solution technique that is capable to solve various types of differential equations. Using this method, governing differential equations are transformed into recursive relations and boundary conditions are changed into algebraic equations. Since the problem of plates on elastic foundation have a great practical importance in modern engineering structures and Winkler foundation model is widely used, plate is assumed on Winkler elastic foundation. In this article functionally graded plate is considered in which material properties vary through the thickness direction by power-law distribution. Analysis results of out of plane displacement of plate on elastic foundation under uniform transverse loads are obtained in different terms of foundation stiffness, material properties and boundary conditions. In order to validate the solution technique, results obtained are compared with the results of the finite element method (FEM). پرونده مقاله -
دسترسی آزاد مقاله
56 - Thermal Buckling Analysis of Circular FGM Plate with Actuator/Actuator Piezoelectric Layer Based on Neutral Plane
محمد مهدی نجفی زاده محسن مالمراد آرش شریفیIn this paper, the thermal buckling analysis of a circular plate made of FGM materials with actuator/actuator piezoelectric layers based on neutral plane, classical plate theory and first order shear deformation plate theory is investigated. Reddy's model is assumed for چکیده کاملIn this paper, the thermal buckling analysis of a circular plate made of FGM materials with actuator/actuator piezoelectric layers based on neutral plane, classical plate theory and first order shear deformation plate theory is investigated. Reddy's model is assumed for material properties of FGM plate. Plate under the thermal loading, nonlinear temperature rise through the thickness and clamped edges is considered. Equilibrium and stability equations are drived using the calculus of variations and applying Euler equations. The obtained results are compared with the numerical values of the critical buckling temperature based on the theories mentioned above, and good agreement is observed between them. پرونده مقاله -
دسترسی آزاد مقاله
57 - Free Vibration Analysis of FGM Cylindrical Shell with Supported Ring Based on Reddy Model under Clamped Boundary Condition
محمد رضا عیسوند زیبائی مهدی سلمان زاده رسول موسوی‌فرIn this paper a study on the vibration of thin cylindrical shells with ring supports and made of functionally graded materials (FGMs) composed of stainless steel and nickel is presented. The properties are graded in the thickness direction according to a volume fraction چکیده کاملIn this paper a study on the vibration of thin cylindrical shells with ring supports and made of functionally graded materials (FGMs) composed of stainless steel and nickel is presented. The properties are graded in the thickness direction according to a volume fraction power-law distribution.The cylindrical shells with ring supports which are arbitrarily placed along the shell and impose zero lateral deflections. The study is carried out based on third order shear deformation shell theory (T.S.D.T). The analysis is carried out using Hamilton’s principle. The governing equations of motion of FGM cylindrical shells are derived based on shear deformation theory. Results are presented on the frequency characteristics, influence of ring support position and the influence of clamed-clamped boundary conditions. پرونده مقاله -
دسترسی آزاد مقاله
58 - Bending Analysis of Rectangular FGM Plates based on the Extended Kantorovich Method
محمد مهدی نجفی زاده مجید علوی فؤاد سلماسی شیما آذریBending analysis of FGM plates under uniform and sinusoidal loaded result in forth order partial differential equation. In this paper the analytical solution is based on the extended Kantorovich iterative procedure. The differential equations for the iterative procedure چکیده کاملBending analysis of FGM plates under uniform and sinusoidal loaded result in forth order partial differential equation. In this paper the analytical solution is based on the extended Kantorovich iterative procedure. The differential equations for the iterative procedure is derived using the Galerkin method. The solution was develope based on the classical plate’s theory (CLPT). The reliability of the present analytical method for FGM, under different boundary condition, was verified and approved when comparing Navier solution and finite element results with ANSYS solution. Since the FGM modeling is impossibility at ANSYS, a macro has used for modeling and analysis.The results show a high accuracy and the iterative process converges very rapidly. It was also found that the final form of the generated solutions is independent of the initial trial function. پرونده مقاله -
دسترسی آزاد مقاله
59 - Stress Analysis of Magneto Thermoelastic and Induction Magnetic Filed in FGM Hallow Sphere
حسن خادمی زاده علی قربان پور آرانی محمد سالاریIn this paper a closed form solution for one-dimensional magnetothermoelastic problem in a functionally graded material (FGM) hollow sphere placed in a uniform magnetic field and temperature field subjected to an internal pressure is obtained using the theory of magneto چکیده کاملIn this paper a closed form solution for one-dimensional magnetothermoelastic problem in a functionally graded material (FGM) hollow sphere placed in a uniform magnetic field and temperature field subjected to an internal pressure is obtained using the theory of magnetothermoelasticity. Hyper-geometric functions are employed to solve the governing equation. The material properties through the graded direction are assumed to be nonlinear with an exponential distribution. The nonhomogeneity of the material in the radial directions is assumed to be power-exponential. The temperature, displacement and stress fields and the perturbation of magnetic field vector are determined and compared with those of the homogeneous case. Hence, the effect of inhomogeneity on the stresses and the perturbation of magnetic field vector distributions are demonstrated. The results of this study are applicable for designing optimum FGM hollow spheres. پرونده مقاله -
دسترسی آزاد مقاله
60 - Nonlinear Finite Element Analysis of Thermoelastic Stresses of FGM Rotating Disk Considering Temperature-Dependency of Material Properties
مهرنوش دمیرچلی محمد آزادیIn the present paper, nonlinear radial and hoop thermoelastic stresses analysis of a disk made of FGMs material is investigated. According to this purpose, finite element method is used. In the present method, second-order one-dimensional element (with three node points چکیده کاملIn the present paper, nonlinear radial and hoop thermoelastic stresses analysis of a disk made of FGMs material is investigated. According to this purpose, finite element method is used. In the present method, second-order one-dimensional element (with three node points) is proposed. The geometrical and stress boundary conditions are defined in the state of non-existence of external pressure and then zero radial stress in the outer layer of the disk, and zero displacement in the center of the disk. Also the temperature distribution is assumed as linear. The material properties changes including temperature-dependency are modeled. Finally, a numerical example is proposed to show the radial displacements, radial and hoop thermoelastic stresses versus radius of the disk for different power (N) from Power-law and different angular velocities. The results show that by increasing both two parameters, N and angular velocity of the disk, the amounts of displacement and stress are increased. At last, temperature-dependency and temperature-independency of material properties is investigated. پرونده مقاله -
دسترسی آزاد مقاله
61 - Nonlinear Vibration Analysis of a Cylindrical FGM Shell on a Viscoelastic Foundation under the Action of Lateral and Compressive Axial Loads
احمد مامندیIn this paper, the nonlinear vibration analysis of a thin cylindrical shell made of Functionally Graded Material (FGM) resting on a nonlinear viscoelastic foundation under compressive axial and lateral loads is studied. Nonlinear governing coupled partial differential e چکیده کاملIn this paper, the nonlinear vibration analysis of a thin cylindrical shell made of Functionally Graded Material (FGM) resting on a nonlinear viscoelastic foundation under compressive axial and lateral loads is studied. Nonlinear governing coupled partial differential equations of motions (PDEs) for cylindrical shell are derived using improved Donnell shell theory. The equations of motions (EOMs) then are solved using the Galerkin method, Volmir’s assumption and the forth-order Runge-Kutta method to obtain dynamic response of the shell including nonlinear frequencies, frequency-amplitude curves and nonlinear radial deflection for the shell of revolution. Afterward, the effect of changing the value of different parameters on the nonlinear dynamic response of the FGM cylindrical shell considering compressive axial and lateral loads, geometric characteristics of the shell, FGM material distribution along direction of the thickness of the shell and coefficients of the viscoelastic foundation are all investigated پرونده مقاله -
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62 - Static Analysis of Orthotropic Functionally Graded Material Cylinders with Finite Length by a Mesh-Free Method
رسول مرادی دستجردی مهرداد فروتن سمیه عبداللهی بکتاشIn this paper static analysis of orthotropic functionally graded material (FGM) cylinders with finite length was carried out by a mesh-free method. MLS shape functions are used for approximation of displacement field in the weak form of equilibrium equation and essentia چکیده کاملIn this paper static analysis of orthotropic functionally graded material (FGM) cylinders with finite length was carried out by a mesh-free method. MLS shape functions are used for approximation of displacement field in the weak form of equilibrium equation and essential boundary conditions are imposed by transformation method. In this simulation, an ax symmetric model is used. Mechanical properties of cylinders were assumed to be variable in the radial direction as a function of volume fraction. In this analysis, effects of the cylinder thickness and length, volume fraction exponent, type of materials layout and essential boundary conditions on displacement fields and stress distribution for orthotropic cylinders are investigated. The results of the proposed method for isotropic FGM cylinders were compared with corresponding results obtained from FEM and previous published works and a very good agreement are seen between them. Also by comparing the stress distributions of orthotropic FGM cylinders and corresponding results of homogeneous multilayered orthotropic cylinders were confirmed. پرونده مقاله -
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63 - Free and Forced Vibration Analysis of Functionally Graded Material Cylinders by a Mesh-Free Method
رسول مرادی دستجردی مهرداد فروتن امین‌الله پوراصغرIn this paper, free and forced vibration analysis of functionally graded material cylinders was carried out by mesh-free and finite element method. In this analysis, MLS shape functions are used for approximation of displacement field in the weak form of motion equation چکیده کاملIn this paper, free and forced vibration analysis of functionally graded material cylinders was carried out by mesh-free and finite element method. In this analysis, MLS shape functions are used for approximation of displacement field in the weak form of motion equation and essential boundary conditions are imposed by transformation method. Resulted set of differential equations are solved using central difference approximation. Mechanical properties of cylinders were assumed to be variable in the radial direction as a function of volume fraction. Effects of geometrical dimensions of the cylinders, exponent of material volume fraction and the effect of loading type were investigated by the proposed model and FEM. Results obtained by this analysis were compared with the analytical solutions and the results of finite element analysis, and a very good agreement was seen between them. پرونده مقاله -
دسترسی آزاد مقاله
64 - The new version of Differential Quadrature Buckling Analyses of FGM Rectangular Plates Under Non-Uniform Distributed In-Plane Loading
محمد مهدی نجفی زاده رضا کاظمی مهرآبادیIn this paper the buckling coefficient of FGM rectangular plates calculated by the new version of differential quadrature method (DQM). At the first the governing differential equation for plate has been calculated and then according to the new version of differential q چکیده کاملIn this paper the buckling coefficient of FGM rectangular plates calculated by the new version of differential quadrature method (DQM). At the first the governing differential equation for plate has been calculated and then according to the new version of differential quadrature method (DQM) the existence derivatives in equation , convert to the amounts of function in the grid points inside of the region is solved .With doing this , The equation will be converted to an eigen value problem and the buckling coefficient is obtained . In the solving of this problem two kinds of loading for all edges are simply supported or clamped are considered and also the effect of power law index over the buckling coefficient is considered . For the case Isotropic the results are compared well with finite element and finite difference results.This fact indicates that the new version of DQ method can be employed for obtaining buckling loads of plates subjected to non–uniform distributed loading for other boundary conditions. پرونده مقاله -
دسترسی آزاد مقاله
65 - Micro1
حسین دهبانیThe origin of the modern theories of a continuum with microstructure goes back to papers by Ericksen and Truesdell (1958), Mindlin (1964), Eringen and Suhubi (1964) and Green and Rivlin (1964). Green (1965) has established the connection of the theory of multipolar co چکیده کاملThe origin of the modern theories of a continuum with microstructure goes back to papers by Ericksen and Truesdell (1958), Mindlin (1964), Eringen and Suhubi (1964) and Green and Rivlin (1964). Green (1965) has established the connection of the theory of multipolar continuum mechanics and the other theories. Much of the theoretical progress in the field is discussed in the books of Kunin (1983), Ciarletta and Iesan (1993) and Eringen (1999). In the theory of micromorphic bodies formulated by Eringen and Suhubi (1964, 1999) the material particle is endowed with three deformable directors and the theory introduces nine extra degrees of freedom over the classical theory. On the basis of the theory of bodies with inner structure, Grot (1969) has established a theory of thermodynamics of elastic bodies with microstructure whose microelements possess microtemperatures. The Clausius–Duhem inequality is modified to include microtemperatures, and the firstorder moment of the energy equations are added to the usual balance laws of a continuum with microstructure. The theory of micromorphic fluids with microtemperatures has been studied in various papers (see, e.g., Koh, 1973; Riha, 1975, 1977; Verma et al., 1979). Riha (1976) has presented a study of heat conduction in materials with microtemperatures. Experimental data for the silicone rubber containing spherical aluminium particles and for human blood were found to conform closely to predicted theoretical thermal conductivity. پرونده مقاله -
دسترسی آزاد مقاله
66 - تحلیل میکروپالر پیزوترمواالستیسیته
حسین دهبانیThe origin of the modern theories of a continuum with microstructure goes back to papers by Ericksen and Truesdell (1958), Mindlin (1964), Eringen and Suhubi (1964) and Green and Rivlin (1964). Green (1965) has established the connection of the theory of multipolar co چکیده کاملThe origin of the modern theories of a continuum with microstructure goes back to papers by Ericksen and Truesdell (1958), Mindlin (1964), Eringen and Suhubi (1964) and Green and Rivlin (1964). Green (1965) has established the connection of the theory of multipolar continuum mechanics and the other theories. Much of the theoretical progress in the field is discussed in the books of Kunin (1983), Ciarletta and Iesan (1993) and Eringen (1999). In the theory of micromorphic bodies formulated by Eringen and Suhubi (1964, 1999) the material particle is endowed with three deformable directors and the theory introduces nine extra degrees of freedom over the classical theory. On the basis of the theory of bodies with inner structure, Grot (1969) has established a theory of thermodynamics of elastic bodies with microstructure whose microelements possess microtemperatures. The Clausius–Duhem inequality is modified to include microtemperatures, and the firstorder moment of the energy equations are added to the usual balance laws of a continuum with microstructure. The theory of micromorphic fluids with microtemperatures has been studied in various papers (see, e.g., Koh, 1973; Riha, 1975, 1977; Verma et al., 1979). Riha (1976) has presented a study of heat conduction in materials with microtemperatures. Experimental data for the silicone rubber containing spherical aluminium particles and for human blood were found to conform closely to predicted theoretical thermal conductivity. پرونده مقاله -
دسترسی آزاد مقاله
67 - thermoelasticity FGM
حسین دهبانیThe origin of the modern theories of a continuum with microstructure goes back to papers by Ericksen and Truesdell (1958), Mindlin (1964), Eringen and Suhubi (1964) and Green and Rivlin (1964). Green (1965) has established the connection of the theory of multipolar co چکیده کاملThe origin of the modern theories of a continuum with microstructure goes back to papers by Ericksen and Truesdell (1958), Mindlin (1964), Eringen and Suhubi (1964) and Green and Rivlin (1964). Green (1965) has established the connection of the theory of multipolar continuum mechanics and the other theories. Much of the theoretical progress in the field is discussed in the books of Kunin (1983), Ciarletta and Iesan (1993) and Eringen (1999). In the theory of micromorphic bodies formulated by Eringen and Suhubi (1964, 1999) the material particle is endowed with three deformable directors and the theory introduces nine extra degrees of freedom over the classical theory. On the basis of the theory of bodies with inner structure, Grot (1969) has established a theory of thermodynamics of elastic bodies with microstructure whose microelements possess microtemperatures. The Clausius–Duhem inequality is modified to include microtemperatures, and the firstorder moment of the energy equations are added to the usual balance laws of a continuum with microstructure. The theory of micromorphic fluids with microtemperatures has been studied in various papers (see, e.g., Koh, 1973; Riha, 1975, 1977; Verma et al., 1979). Riha (1976) has presented a study of heat conduction in materials with microtemperatures. Experimental data for the silicone rubber containing spherical aluminium particl پرونده مقاله
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