eng
Islamic Azad University Arak Branch
Journal of Solid Mechanics
2008-3505
2008-7683
2012-12-30
4
4
327
338
514488
Theory of Generalized Piezoporo Thermoelasticity
M Jabbari
mohsen.jabbari@gmail.com
1
A Yooshi
2
Postgraduate School of Engineering, South Tehran Branch, Islamic Azad University
Postgraduate School of Engineering, South Tehran Branch, Islamic Azad University
In this paper, the basic constitutive equations and equations of motion are derived to describe the behavior of thermoelastic porous piezoelectric medium by using Biot’s theory and the theory of generalized thermoelasticity with on relaxation time (Lord-Shulman). The electrical enthalpy density function is derived in the general coordinates. Also, clear definitions for the poroelastic modulus, electrical, thermal and additional mixed coefficients are embedded. The uniqueness of the solution for the complete system of equations is presented.
http://jsm.iau-arak.ac.ir/article_514488_d2134e2116807822360c181779b6cfb2.pdf
Porous piezo materials
Generalized thermoelasticity
Biot’s theory
Two phase
Electro-dynamic Maxwell’s equation
eng
Islamic Azad University Arak Branch
Journal of Solid Mechanics
2008-3505
2008-7683
2012-12-30
4
4
339
354
514489
Analytical Solution for Electro-mechanical Behavior of Piezoelectric Rotating Shaft Reinforced by BNNTs Under Non-axisymmetric Internal Pressure
A Ghorbanpour Arani
aghorban@kashanu.ac.ir
1
E Haghparast
2
S Amir
3
Faculty of Mechanical Engineering, University of Kashan--- Institute of Nanoscience & Nanotechnology, University of Kashan
Faculty of Mechanical Engineering, University of Kashan
Faculty of Mechanical Engineering, University of Kashan
In this study, two-dimensional electro-mechanical analysis of a composite rotating shaft subjected to non-axisymmetric internal pressure and applied voltage is investigated where hollow piezoelectric shaft reinforced by boron nitride nanotubes (BNNTs). Composite structure is modeled based on piezoelectric fiber reinforced composite (PFRC) theory and a representative volume element has been considered for predicting the elastic, piezoelectric and dielectric properties of the composite rotating shaft. Distribution of radial, circumferential, shear and effective stresses and electric displacement in composite rotating shaft are determined based on Fourier series. The detailed parametric study is conducted, focusing on the remarkable effects of angular velocity, electric potential, volume fraction and orientation angle of BNNTs on the distribution of stresses. The results show that properties of the piezoelectric shaft as matrix have significant influence on the electro-mechanical stresses where the PZT-4 has less effective stresses against PVDF. Therefore, PZT-4 could be considered for improving optimum design of rotating piezoelectric shaft under electric field and non-axisymmetric mechanical loadings.
http://jsm.iau-arak.ac.ir/article_514489_650775031588f3cb22bc33b4536a1a92.pdf
Composite rotating shaft
Micro-electro-mechanical model
Non-axisymmetric pressure
BNNTs fiber
eng
Islamic Azad University Arak Branch
Journal of Solid Mechanics
2008-3505
2008-7683
2012-12-30
4
4
355
371
514490
Analysis of Laminated Soft Core Sandwich Plate Having Interfacial Imperfections by an Efficient C0 FE Model
R.P Khandelwal
ravi.iitdelhi@gmail.com
1
A Chakrabarti
2
P Bhargava
3
Department of Civil Engineering, Indian Institute of Technology
Department of Civil Engineering, Indian Institute of Technology
Department of Civil Engineering, Indian Institute of Technology
An efficient C<sup>0</sup> continuous two dimensional (2D) finite element (FE) model is developed based on a refined higher order shear deformation theory (RHSDT) for the static analysis of soft core sandwich plate having imperfections at the layer interfaces. In this (RHSDT) theory, the in-plane displacement field for the face sheets and the core is obtained by superposing a globally varying cubic displacement field on a zig-zag linearly varying displacement field. The transverse displacement is assumed to have a quadratic variation within the core and it remains constant in the faces beyond the core. In this theory, the interfacial imperfection is represented by a liner spring-layer model. The proposed model satisfies the condition of transverse shear stress continuity at the layer interfaces and the zero transverse shear stress condition at the top and bottom of the sandwich plate. The nodal field variables are chosen in an efficient manner to circumvent the problem of C<sup>1</sup> continuity requirement of the transverse displacements associated with the RHSDT. The proposed model is implemented to analyze the laminated composites and sandwich plates having interfacial imperfection. Many new results are also presented which should be useful for the future research.
http://jsm.iau-arak.ac.ir/article_514490_2fd814203da5b802e977cdca0961a7a1.pdf
Composites
Finite element methods
Interfacial imperfection
Sandwich plate
Soft core
eng
Islamic Azad University Arak Branch
Journal of Solid Mechanics
2008-3505
2008-7683
2012-12-01
4
4
372
385
514491
Closed-form Solution of Dynamic Displacement for SLGS Under Moving the Nanoparticle on Visco-Pasternak Foundation
A Ghorbanpour Arani
aghorban@kashanu.ac.ir
1
A Shiravand
2
S Amir
3
Faculty of Mechanical Engineering, University of Kashan--- Institute of Nanoscience & Nanotechnology, University of Kashan
Faculty of Mechanical Engineering, University of Kashan
Faculty of Mechanical Engineering, University of Kashan
In this paper, forced vibration analysis of a single-layered graphene sheet (SLGS) under moving a nanoparticle is carried out using the non-local elasticity theory of orthotropic plate. The SLGS under moving the nanoparticle is placed in the elastic and viscoelastic foundation which are simulated as a Pasternak and Visco-Pasternak medium, respectively. Movement of the nanoparticle is considered as a linear movement with constant velocity from an edge to another edge of graphene sheet. Using the non-linear Von Kármán strain-displacement relations and Hamilton’s principle, the governing differential equations of motion are derived. The differential equation of motion for all edges simply supported boundary condition is solved by an analytical method and therefore, the dynamic displacement of SLGS is presented as a closed-form solution of that. The influences of medium stiffness (Winkler, Pasternak and damper modulus parameter), nonlocal parameter, aspect ratio, mechanical properties of graphene sheet, time and velocity parameter on dimensionless displacement (dynamic displacement to static displacement of SLGS) are studied. The results indicate that, as the values of stiffness modulus parameter increase, the maximum dynamic displacement of SLGS decreases. Therefore, the results are in good agreement with the previous researches.
http://jsm.iau-arak.ac.ir/article_514491_63f0c9ec67fe2b173b29c18e7f8f6cf0.pdf
Graphene sheet
Visco-Pasternak medium
, Moving nanoparticle
Closed-form solution
Non-local elasticity theory
eng
Islamic Azad University Arak Branch
Journal of Solid Mechanics
2008-3505
2008-7683
2012-12-30
4
4
386
401
514492
Thermo-elastic Damping in a Capacitive Micro-beam Resonator Considering Hyperbolic Heat Conduction Model and Modified Couple Stress Theory
M Najafi
1
G Rezazadeh
g.rezazadeh@urmia.ac.ir
2
R Shabani
3
Mechanical Engineering Department, Urmia University
Mechanical Engineering Department, Urmia University
Mechanical Engineering Department, Urmia University
In this paper, the quality factor of thermo-elastic damping in an electro-statically deflected micro-beam resonator has been investigated. The thermo-elastic coupled equations for the deflected micro-beam have been derived using variational and Hamilton principles based on modified couple stress theory and hyperbolic heat conduction model. The thermo-elastic damping has been obtained discretizing the governing equations over spatial domain and applying complex frequency approach. The effects of the applied bias DC voltage, playing simultaneously role of an external force and softening parameter, on the quality factor have been studied. The obtained results of the modified couple stress and classic theories are compared and the effects of the material internal length-scale parameter on the differences between results of two theories have been discussed. In addition, the effects of different parameters such as beam length and ambient temperature on the quality factor have been studied.
http://jsm.iau-arak.ac.ir/article_514492_0382838e03088b07735651899502e020.pdf
Modified couple stress theory
Thermo-elastic damping
Length-scale parameter
Electrostatic force
eng
Islamic Azad University Arak Branch
Journal of Solid Mechanics
2008-3505
2008-7683
2012-12-30
4
4
402
415
514493
Torsional Waves in Prestressed Fiber Reinforced Medium Subjected to Magnetic Field
R Kakar
rkakar_163@rediffmail.com
1
S Kakar
2
Principal, DIPS Polytechnic College, Hoshiarpur
Faculty of Electrical Engineering, SBBSIET Padhiana Jalandhar
The propagation of torsional waves in a prestressed fiber-reinforced half-space under the effect of magnetic field and gravity has been discussed. The problem has been solved analytically using Whittaker function to obtain the exact solution frequency equations. Numerical results for stress, gravity and magnetic field are given and illustrated graphically. Comparisons are made with the results predicted by the boundary value condition for rigid boundary and for traction free boundary in the presence and in the absence of the effect of a magnetic field, gravity and stress. It is found that the reinforcement, gravity and magnetic field have great effects on the distribution.
http://jsm.iau-arak.ac.ir/article_514493_c0362356668cd96b9cdc798453fc8259.pdf
Magnetoelastic
Torsional waves
Initial stress
Fiber reinforced medium
Whittaker function
eng
Islamic Azad University Arak Branch
Journal of Solid Mechanics
2008-3505
2008-7683
2012-12-30
4
4
416
425
514495
Frequency Response Analysis of a Capacitive Micro-beam Resonator Considering Residual and Axial Stresses and Temperature Changes Effects
S Valilou
svalilou@iaukhoy.ac.ir
1
M Jalilpour
2
Department of Mechanical Engineering, Khoy Branch, Islamic Azad University
Department of Mechanical Engineering, Khoy Branch, Islamic Azad University
This paper presents a study on the frequency response of a capacitive micro-beam resonator under various applied stresses. The governing equation whose solution holds the answer to all our questions about the mechanical behavior is the nonlinear electrostatic equation. Due to the nonlinearity and complexity of the derived equation analytical solution are not generally available; therefore, the obtained differential equation has been solved by using a step by step linearization scheme and a Galerkin based reduced order model. The obtained static pull-in voltages have been validated by previous reports and a good agreement has been achieved. The dynamic behavior of the beam under residual, axial and thermal stresses has been investigated. It has been shown that applying the positive residual stress and negative temperature changes shifts right the frequency response and decrease the vibration amplitude and vice versa. Also, it has been shown that applying the bias DC voltage beside the exciting AC voltage decreases the stiffness of the system and so, shifts left the frequency response and increases the vibration amplitude.
http://jsm.iau-arak.ac.ir/article_514495_b334dad44e98795d7bb1e5cfc68a17c5.pdf
MEMS
Resonator
Residual stress
Axial stress
Temperature Changes
Frequency Response
eng
Islamic Azad University Arak Branch
Journal of Solid Mechanics
2008-3505
2008-7683
2012-12-30
4
4
426
440
514500
Analysis of Five Parameter Viscoelastic Model Under Dynamic Loading
R Kakar
rkakar_163@rediffmail.com
1
K Kaur
2
K.C Gupta
3
Principal, DIPS Polytechnic College, Hoshiarpur
Faculty of Science, BMSCTE, Muktsar
Faculty of Science, BMSCTE, Muktsar
The purpose of this paper is to analysis the viscoelastic models under dynamic loading. A five-parameter model is chosen for study exhibits elastic, viscous, and retarded elastic response to shearing stress. The viscoelastic specimen is chosen which closely approximates the actual behavior of a polymer. The module of elasticity and viscosity coefficients are assumed to be space dependent i.e. functions of in non-homogeneous case and stress-strain are harmonic functions of time The expression for relaxation time for five parameter viscoelastic model is obtained by using constitutive equation. The dispersion equation is obtained by using Ray techniques. The model is justified with the help of cyclic loading for maxima or minima.
http://jsm.iau-arak.ac.ir/article_514500_7dedc60fa94e136eb9bfbcfdeacd271d.pdf
Shear waves
Viscoelastic media
Asymptotic method
dynamic loading