eng
Islamic Azad University Arak Branch
Journal of Solid Mechanics
2008-3505
2008-7683
2009-12-30
1
4
260
270
514307
Analysis of Wave Motion in a Micropolar Transversely Isotropic Medium
R.R Gupta
rajani_gupta_83@yahoo.com
1
R Kumar
rajneesh_kuk@rediffmail.com
2
Department of Mathematics, Kurukshetra University, Kurukshetra
Department of Mathematics, Kurukshetra University, Kurukshetra
The present investigation deals with the propagation of waves in a micropolar transversely isotropic layer. Secular equations for symmetric and skew-symmetric modes of wave propagation in completely separate terms are derived. The amplitudes of displacements and microrotation were also obtained. Finally, the numerical solution was carried out for aluminium epoxy material and the dispersion curves. Amplitudes of displacements and microrotation for symmetric and skew-symmetric wave modes are presented to evince the effect of anisotropy. Some particular cases are also deduced.
http://jsm.iau-arak.ac.ir/article_514307_fcde556b79ccd3253b32ad78c2d4a8ad.pdf
Micropolar
Transversely isotropic
Amplitude ratios
eng
Islamic Azad University Arak Branch
Journal of Solid Mechanics
2008-3505
2008-7683
2009-12-30
1
4
271
288
514308
Temperature Effects on Nonlinear Vibration of FGM Plates Coupled with Piezoelectric Actuators
F Ebrahimi
febrahimy@ut.ac.ir
1
A Rastgoo
2
Faculty of Mechanical Engineering, College of Engineering, University of Tehran
Faculty of Mechanical Engineering, College of Engineering, University of Tehran
An 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.
http://jsm.iau-arak.ac.ir/article_514308_b583e58ead2ec85d1db43e980537f48f.pdf
FGM plate
Nonlinear vibration
Piezoelectric actuators
eng
Islamic Azad University Arak Branch
Journal of Solid Mechanics
2008-3505
2008-7683
2009-12-30
1
4
289
299
514309
Buckling Analysis of a Double-Walled Carbon Nanotube Embedded in an Elastic Medium Using the Energy Method
A Ghorbanpour Arani
aghorban@kashanu.ac.ir
1
M Shokravi
2
M Mohammadimehr
3
Department of Mechanical Engineering, University of Kashan
Department of Mechanical Engineering, University of Kashan
Department of Mechanical Engineering, University of Kashan
The axially compressed buckling of a double-walled carbon nanotabe surrounded by an elastic medium using the energy and the Rayleigh-Ritz methods is investigated in this paper. In this research, based on the elastic shell models at nano scale, the effects of the van der Waals forces between the inner and the outer tubes, the small scale and the surrounding elastic medium on the critical buckling load are considered. Normal stresses at the outer tube medium interface are also included in the current analysis. An expression is derived relating the external pressure to the buckling mode number, from which the critical pressure can be obtained. It is seen from the results that the critical pressure is dependent on the outer radius to thickness ratio, the material parameters of the surrounding elastic medium such as Young’s modulus and Poisson’s ratio. Moreover, it is shown that the critical pressure descend very quickly with increasing the half axial wave numbers.
http://jsm.iau-arak.ac.ir/article_514309_84dfcc74e229176cec94280ec5df2a92.pdf
Buckling
DWCNT
Elastic medium
Energy method
eng
Islamic Azad University Arak Branch
Journal of Solid Mechanics
2008-3505
2008-7683
2009-12-30
1
4
300
312
514310
Analysis on Centrifugal Load Effect in FG Hollow Sphere Subjected to Magnetic Field
S.M.R Khalili
smrkhalili2005@gmail.com
1
A.H Mohazzab
2
M Jabbari
3
Department of Mechanical Engineering, Faculty of Engineering, Islamic Azad University, South Tehran Branch-Faculty of Engineering, Kingston University
Department of Mechanical Engineering, Faculty of Engineering, Islamic Azad University, South Tehran Branch
Department of Mechanical Engineering, Faculty of Engineering, Islamic Azad University, South Tehran Branch
This paper presents the effect of centrifugal load in functionally graded (FG) hollow sphere subjected to uniform magnetic field. Analytical solution for stresses and perturbation of the magnetic field vector are determined using the direct method and the power series method. The material stiffness, the magnetic permeability and the density vary continuously across the thickness direction according to the power law functions of radial directions. Magnetic field results in decreasing the radial displacement, the radial and shear stresses due to centrifugal load and has a negligible effect on circumferential displacement and also small effect compared with the other quantities on the circumferential stress due to centrifugal load. Increasing the angular velocity results in increasing the all above quantities due to magnetic field. With increasing the power law indices the radial displacement, the shear and circumferential stresses due to centrifugal load and magnetic field all are decreased and the radial stress due to centrifugal load and magnetic field increased.
http://jsm.iau-arak.ac.ir/article_514310_1c25fbdf328b78471d143ee7116e0021.pdf
Centrifugal load
FG
Hollow cylinder
Magnetic Field
eng
Islamic Azad University Arak Branch
Journal of Solid Mechanics
2008-3505
2008-7683
2009-12-30
1
4
313
327
514311
A Rapidly Convergent Nonlinear Transfinite Element Procedure for Transient Thermoelastic Analysis of Temperature-Dependent Functionally Graded Cylinders
M Shariyat
m_shariyat@yahoo.com
1
Faculty of Mechanical Engineering, K.N.T. University of Technology
In the present paper, the nonlinear transfinite element procedure recently published by the author is improved by introducing an enhanced convergence criterion to significantly reduce the computational run-times. It is known that transformation techniques have been developed mainly for linear systems, only. Due to using a huge number of time steps, employing the conventional time integration methods requires quite huge computational time and leads to remarkable error accumulation, numerical instability, or numerical damping, especially for long investigation times. The present method specially may be extended to problems where the required time steps are of the order of the round-off errors (e.g., coupled thermoelasticty problems). The present procedure is employed for transient thermoelastic analysis of thick-walled functionally graded cylinders with temperature-dependent material properties, as an example. To reduce the effect of the artificial local heat and stress shock source generation at the mutual boundaries of the elements, second order elements are used. Influences of various parameters on the temperature and stress distributions are investigated. Furthermore, results of the proposed transfinite element technique are compared with the results obtained by other references to verify the validity, accuracy, and efficiency of the proposed method.
http://jsm.iau-arak.ac.ir/article_514311_09d4d88d6a04042a3be92d069df903e6.pdf
Nonlinear transfinite element
Transient thermoelastic analysis
Enhanced convergence
Functionally graded cylinders
Temperature-dependency
eng
Islamic Azad University Arak Branch
Journal of Solid Mechanics
2008-3505
2008-7683
2009-12-30
1
4
328
342
514312
Effects of Geometric Nonlinearity on Stress Analysis in Large Amplitude Vibration of Moderately Thick Annular Functionally Graded Plate
M.H Amini
mhamini@ut.ac.ir
1
A Rastgoo
2
M Soleimani
3
Faculty of Mechanical Engineering, College of Engineering, University of Tehran
Faculty of Mechanical Engineering, College of Engineering, University of Tehran
Faculty of Mechanical Engineering, College of Engineering, University of Tehran
This paper deals with the nonlinear free vibration of thick annular functionally graded material plates. The thickness is assumed to be constant. 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 formulations are based on the first-order shear deformation plate theory and von Kármán-type equation. For harmonic vibrations, by using assumed-time-mode method sinusoidal oscillations are assumed, then the time variable is eliminated by applying Kantorovich averaging method. Thus, the basic governing equations for the problem are reduced to a set of ordinary differential equations in term of radius. The results reveal that vibration amplitude and volume fraction have significant effects on the resultant stresses in large amplitude vibration of the functionally graded thick plate.
http://jsm.iau-arak.ac.ir/article_514312_46319e2cdbb668fca65ea58e83216ae6.pdf
Functionally graded material
Large amplitude vibration
Stress Analysis
Thick annular plate
eng
Islamic Azad University Arak Branch
Journal of Solid Mechanics
2008-3505
2008-7683
2009-12-30
1
4
343
357
514313
An Exact Solution for Classic Coupled Thermoporoelasticity in Cylindrical Coordinates
M Jabbari
mjabbari@oiecgroup.com
1
H Dehbani
2
Postgraduate School, South Tehran Branch Islamic Azad University
Postgraduate School, South Tehran Branch Islamic Azad University
In this paper the classic coupled thermoporoelasticity model of hollow and solid cylinders under radial symmetric loading condition (<em>r</em>, <em>t</em>) is considered. A full analytical method is used and an exact unique solution of the classic coupled equations is presented. The thermal and pressure boundary conditions, the body force, the heat source, and the injected volume rate per unit volume of a distribute water source are considered in the most general forms, and no limiting assumption is used. This generality allows simulation of various applicable problems.
http://jsm.iau-arak.ac.ir/article_514313_89c2406d7f603d186ad27c22c1ea3305.pdf
Coupled Thermoporoelasticity
Hollow cylinder
Exact solution
eng
Islamic Azad University Arak Branch
Journal of Solid Mechanics
2008-3505
2008-7683
2009-12-30
1
4
358
364
514314
First-Order Formulation for Functionally Graded Stiffened Cylindrical Shells Under Axial Compression
A Hasani
abolfazl_hassani1357@yahoo.com
1
Department of Mechanical Engineering, Islamic Azad University, Arak Branch
The buckling analysis of stiffened cylindrical shells by rings and stringers made of functionally graded materials subjected to axial compression loading is presented. It is assumed that the material properties vary as a power form of the thickness coordinate variable. The fundamental relations, the equilibrium and stability equations are derived using the first order shear deformation theory. Resulting equations are employed to obtain the critical buckling loads. The effects of the material properties and geometry of shell on the critical buckling loads are examined. Excellent agreement with the results in the literature indicates the correctness of the proposed closed form solution.
http://jsm.iau-arak.ac.ir/article_514314_ae76398e26c658602c2725b0951bba53.pdf
Functionally graded material
Stiffened cylindrical shell
First-order theory
Axial compression