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CONTENTS
Volume 5, Number 4, December 2016
 

Abstract
In this article, the buckling responses of functionally graded curved (spherical, cylindrical, hyperbolic and elliptical) shell panels under elevated temperature load are investigated numerically using finite element steps. The effective material properties of the functionally graded shell panel are evaluated using Voigt

Key Words
FGM; thermal buckling; single/doubly curved panel; HSDT; ANSYS

Address
Vishesh R. Kar: Department of Design and Automation, School of Mechanical Engineering, VIT University Vellore: 632014, India

Subrata K. Panda: Department of Mechanical Engineering, National Institute of Technology, Rourkela: 769008, India

Trupti R. Mahapatra: School of Mechanical Engineering, KIIT University, Bhubaneswar: 751024, India

Abstract
In this paper, a higher order shear and normal deformation theory is presented for functionally graded material (FGM) plates. By dividing the transverse displacement into bending, shear and thickness stretching parts, the number of unknowns and governing equations for the present theory is reduced, significantly facilitating engineering analysis. Indeed, the number of unknown functions involved in the present theory is only five, as opposed to six or even greater numbers in the case of other shear and normal deformation theories. The present theory accounts for both shear deformation and thickness stretching effects by a hyperbolic variation of ail displacements across the thickness and satisfies the stress-free boundary conditions on the upper and lower surfaces of the plate without requiring any shear correction factor. Equations of motion are derived from Hamilton&aqute;s principle. Analytical solutions for the bending and free vibration analysis are obtained for simply supported plates. The obtained results are compared with three-dimensional and quasi- three-dimensional solutions and those predicted by other plate theories. It can be concluded that the present theory is not only accurate but also simple in predicting the bending and free vibration responses of functionally graded plates.

Key Words
Functionally Graded Material; power law index; Higher-order Shear Deformation Theory; Navier solution

Address
Belkacem Adim and Tahar Hassaine Daouadji: Departement de genie civil , Universite Ibn Khaldoun Tiaret; BP 78 Zaaroura, 14000 Tiaret, Algerie

Belkacem Adim and Tahar Hassaine Daouadji: Ibn Khaldoun de Tiaret, Algerie

Abstract
Thermo-mechanical buckling problem of functionally graded (FG) nanoplates supported by Pasternak elastic foundation subjected to linearly/non-linearly varying loadings is analyzed via the nonlocal elasticity theory. Two opposite edges of the nanoplate are subjected to the linear and nonlinear varying normal stresses. Elastic properties of nanoplate change in spatial coordinate based on a powerlaw form. Eringen

Key Words
anoplates buckling; functionally graded material; linear and nonlinear varying loading; thermal loading; Pasternak foundation; nonlocal elasticity theory; Navier

Address
Department of Mechanical Engineering, Faculty of Engineering, Imam Khomeini International University, Postal code: 3414916818, Qazvin, Iran

Abstract
Mechanical properties of Al/Al2O3 and Al/B4C composites prepared through powder metallurgy are estimated up to 50% Al2O3 and 35% B4C weight fractions using micromechanics models and experiments. The experimental Young\'s modulus up to 0.40 weight fraction of ceramic is found to lie closely between Ravichandran\'s/Hashin-Shtrikman lower/upper bounds, and close to self consistent method/Miller and Lannutti method/modified rule of mixture/fuzzy logic method single value predictions. Measured Poisson\'s ratio lies between rule of mixture/Ravichandran lower and upper bound/modified Ravichandran upper bounds. Experimental Charpy energy lies between Hopkin-chamis method/equivalent charpy energy/Ravichandran lower limit up to 20%, and close to the reciprocal rule of mixture for higher Al2O3 content. Rockwell hardness (RB) and Micro-hardness of Al/Al2O3 are closer to modified rule of mixture predictions.

Key Words
mechanical properties; hardness; micro-mechanics; powder processing; functionally graded material

Address
Vinod K. Pandey: Research and Development Establishment (Engineers), Pune, India
Badri P. Patel: Applied Mechanics Department, Indian Institute of Technology Delhi, New Delhi, India
Siddalingappa Guruprasad: DRDO HQ, New Delhi, India

Abstract
Present disquisition proposes an analytical solution method for exploring the buckling characteristics of porous magneto-electro-elastic functionally graded (MEE-FG) plates with various boundary conditions for the first time. Magneto electro mechanical properties of FGM plate are supposed to change through the thickness direction of plate. The rule of power-law is modified to consider influence of porosity according to two types of distribution namely even and uneven. Pores possibly occur inside FGMs due the result of technical problems that lead to creation of micro-voids in these materials. The variation of pores along the thickness direction influences the mechanical and physical properties. Four-variable tangential-exponential refined theory is employed to derive the governing equations and boundary conditions of porous FGM plate under magneto-electrical field via Hamilton

Key Words
buckling analysis, MEE-FG plate; porous materials; refined plate theory

Address
Farzad Ebrahimi and Ali Jafari: Department of Mechanical Engineering, Faculty of Engineering, Imam Khomeini International University, Qazvin, Iran

Abstract
Analytical investigations were performed of a longitudinal crack representing a cylindrical surface in circular shafts loaded in torsion with taking into account the non-linear material behavior. Both functionally graded and multilayered shafts were analyzed. It was assumed that the material is functionally graded in radial direction. The mechanical behavior of shafts was modeled by using non-linear constitutive relations between the shear stresses and shear strains. The fracture was studied in terms of the strain energy release rate. Within the framework of small strain approach, the strain energy release rate was derived in a function of the torsion moments in the cross-sections ahead and behind the crack front. The analytical approach developed was applied to study the fracture in a clamped circular shaft. In order to verify the solution derived, the strain energy release rate was determined also by considering the shaft complimentary strain energy. The effects were evaluated of material properties, crack location and material non-linearity on the fracture behavior. The results obtained can be applied for optimization of the shafts structure with respect to the fracture performance. It was shown that the approach developed in the present paper is very useful for studying the longitudinal fracture in circular shafts in torsion with considering the material non-linearity.

Key Words
functionally graded material; torsion; fracture; elastic-plastic behavior; analytical solution

Address
Victor I. Rizov: Department of Technical Mechanics, University of Architecture, Civil Engineering and Geodesy,
1 Chr. Smirnensky blvd., 1046 - Sofia, Bulgaria


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