eng
Islamic Azad University Arak Branch
Journal of Solid Mechanics
2008-3505
2008-7683
2014-09-30
6
3
240
254
514599
Reflection and Transmission of Longitudinal Wave at Micropolar Viscoelastic Solid/Fluid Saturated Incompressible Porous Solid Interface
N Kumari
neelamkumaricdlu@gmail.com
1
Department of Mathematics, Ch. Devi Lal University, Sirsa
In this paper, the reflection and refraction of longitudinal wave from a plane surface separating a micropolar viscoelastic solid half space and a fluid saturated incompressible half space is studied. A longitudinal wave (P-wave) impinges obliquely at the interface. Amplitude ratios for various reflected and transmitted waves have been obtained. Then these amplitude ratios have been computed numerically for a specific model and results thus obtained are shown graphically with angle of incidence of incident wave. It is found that these amplitude ratios depend on angle of incidence of the incident wave as well as on the properties of media. A particular case when longitudinal wave reflects at free surface of micropolar viscoelastic solid has been deduced and discussed. From the present investigation, a special case when fluid saturated porous half space reduces to empty porous solid has also been deduced and discussed with the help of graphs.
http://jsm.iau-arak.ac.ir/article_514599_7f51124ab981998e9a8cdc4acd819373.pdf
Micropolar viscoelastic solid
Porous
Reflection
Longitudinal wave
Amplitude ratios
eng
Islamic Azad University Arak Branch
Journal of Solid Mechanics
2008-3505
2008-7683
2014-09-30
6
3
255
264
514600
Investigation of Vibrational Behavior of Perfect and Defective Carbon Nanotubes Using Non–Linear Mass–Spring Model
A.A Shariati
1
A.R Golkarian
2
M Jabbarzadeh
jabbarzadeh@mshdiau.ac.ir
3
Department of Mechanical Engineering, Mashhad Branch, Islamic Azad University
Department of Mechanical Engineering, Mashhad Branch, Islamic Azad University
Department of Mechanical Engineering, Mashhad Branch, Islamic Azad University
In the present study, the effects of arrangement and distribution of multifarious types of defects on fundamental frequency of carbon nanotubes are investigated with respect to different chirality and boundary conditions. Interatomic interactions between each pair of carbon atoms are modeled using two types of non–linear spring–like elements. To obtain more information about the influences of defects; the effects of location, number and distribution (gathered or scattered defects) of two most common types of defects (vacancy and Stone–Wales defects) are examined on vibrational behavior of carbon nanotubes. Obtained results are in good agreement with the results reported in other literature. The results show that, gathered vacancy defects cause to a reduction in natural frequency of nanotubes, especially in the case of fix–fix boundary condition. It is also observed that the effect of defects depends on chirality intensively. In addition, the influence of the first vacancy defect is significantly more than the first Stone–Wales defect.
http://jsm.iau-arak.ac.ir/article_514600_82f7c2c5b4496c6559ef012680496bc3.pdf
Carbon Nanotube
Vacancy defect
Stone–wales defect
Natural frequency
Non–linear spring
eng
Islamic Azad University Arak Branch
Journal of Solid Mechanics
2008-3505
2008-7683
2014-09-30
6
3
265
277
514601
Nonlinear Dynamic Buckling of Viscous-Fluid-Conveying PNC Cylindrical Shells with Core Resting on Visco-Pasternak Medium
A Ghorbanpour Arani
aghorban@kashanu.ac.ir
1
A.A Mosallaie Barzoki
2
R Kolahchi
3
Faculty of Mechanical Engineering, University of Kashan--- Institute of Nanoscience & Nanotechnology, University of Kashan, Kashan
Faculty of Mechanical Engineering, University of Kashan
Faculty of Mechanical Engineering, University of Kashan
The use of intelligent nanocomposites in sensing and actuation applications has become quite common over the past decade. In this article, electro-thermo-mechanical nonlinear dynamic buckling of an orthotropic piezoelectric nanocomposite (PNC) cylindrical shell conveying viscous fluid is investigated. The composite cylindrical shell is made from Polyvinylidene Fluoride (PVDF) and reinforced by zigzag boron nitride nanotubes (BNNTs) where characteristics of the equivalent PNC being determined using micro-mechanical model. The poly ethylene (PE) foam-core is modeled based on Pasternak foundation. Employing the charge equation, Donnell's theory and Hamilton's principle, the four coupled nonlinear differential equations containing displacement and electric potential terms are derived. Harmonic differential quadrature method (HDQM) is applied to obtain the critical dynamic buckling load. A detailed parametric study is conducted to elucidate the influences of the geometrical aspect ratio, in-fill ratio of core, viscoelastic medium coefficients, material types of the shell and temperature gradient on the dynamic buckling load of the PNC cylindrical shell. Results indicate that the dimensionless critical dynamic buckling load increases when piezoelectric effect is considered.
http://jsm.iau-arak.ac.ir/article_514601_041e0a5926817d1206fc31e834732f3b.pdf
BNNTs
nanocomposite
Cylindrical shell conveying viscous fluid
Nonlinear dynamic buckling response
HDQM
eng
Islamic Azad University Arak Branch
Journal of Solid Mechanics
2008-3505
2008-7683
2014-09-30
6
3
278
288
514602
Energy-Based Prediction of Low-Cycle Fatigue Life of CK45 Steel and SS316 Stainless Steel
M Shariati
mshariati44@um.ac.ir
1
H Mehrabi
2
Department of Mechanical Engineering, Ferdowsi University of Mashhad
Department of Mechanical Engineering, Shahrood University of Technology
In this paper, low cycle fatigue life of CK45 steel and SS316 stainless steel under strain-controlled loading are experimentally investigated. In addition, the impact of mean strain and strain amplitude on the fatigue life and cyclic behavior of the materials are studied. Furthermore, it is attempted to predict fatigue life using energy and SWT damage parameters. The experimental results demonstrate that increase in strain amplitude decreases fatigue life for both materials, strain amplitude has a remarkable effect on fatigue life, and the impact of mean strain is approximately negligible. Furthermore, the energy damage parameter provides more accurate prediction of fatigue life for both materials.
http://jsm.iau-arak.ac.ir/article_514602_a7e95c65d968b8b16420848443cc4a6e.pdf
low cycle fatigue
Damage parameter
CK45 Steel
SS316 stainless steel
Cyclic behavior
eng
Islamic Azad University Arak Branch
Journal of Solid Mechanics
2008-3505
2008-7683
2014-09-30
6
3
289
298
514603
Vibration Analysis of a Nonlinear Beam Under Axial Force by Homotopy Analysis Method
A.A Motallebi
1
M Poorjamshidian
2
J Sheikhi
3
Department of Mechanical Engineering, Imam Hossein University
Department of Mechanical Engineering, Imam Hossein University
Civil Engineering, Imam Hossein University
In this paper, Homotopy Analysis Method is used to analyze free non-linear vibrations of a beam simply supported by pinned ends under axial force. Mid-plane stretching is also considered for dynamic equation extracted for the beam. Galerkin decomposition technique is used to transform a partial dimensionless nonlinear differential equation of dynamic motion into an ordinary nonlinear differential equation. Then Homotopy Analysis Method is employed to obtain an analytic expression for nonlinear natural frequencies. Effects of design parameters including axial force and slenderness ratio on nonlinear natural frequencies are studied. Moreover, effects of factors of nonlinear terms on the general shape of the time response are taken into account. Combined Homotopy-Pade technique is used to reduce the number of approximation orders without affecting final accuracy. The results indicate increased speed of convergence as Homotopy and Pade are combined. The obtained analytic expressions can be used for a vast range of data. Comparison of the results with numerical data indicated a good conformance. Having compared accuracy of this method with that of the Homotopy perturbation analytic method, it is concluded that Homotopy Analysis Method is a very strong method for analytic and vibration analysis of structures.
http://jsm.iau-arak.ac.ir/article_514603_0b18f85c0ca418c61f1c59ba14b428dd.pdf
Nonlinear vibration
Homotopy Analysis Method
Beam axial force
Stretching effect
eng
Islamic Azad University Arak Branch
Journal of Solid Mechanics
2008-3505
2008-7683
2014-09-30
6
3
299
309
514604
Analysis of Mode III Fraction in Functionally Graded Plate with Linearly Varying Properties
M.R Torshizian
torshizian@mshdiau.ac.ir
1
Mechanical Engineering Department, Mashhad Branch, Islamic Azad University
A model is provided for crack problem in a functionally graded semi-infinite plate under an anti-plane load. The characteristic of material behavior is assumed to change in a linear manner along the plate length. Also the embedded crack is placed in the direction of the material change. The problem is solved using two separate techniques. Primary, by applying Laplace and Fourier transformation, the governing equation for the crack problem is converted to the solution of a singular integral equation system. Then, finite element technique is employed to analyze this problem by considering quadrilateral eight nodded singular element near the crack tips. The effects of material non-homogeneity and crack length on the stress intensity factor are studied and the results of two methods are judged against each other.
http://jsm.iau-arak.ac.ir/article_514604_4dada780855f04b5d4d634ebd0b16202.pdf
Functionally graded material
Stress intensity factor
Linear material properties
eng
Islamic Azad University Arak Branch
Journal of Solid Mechanics
2008-3505
2008-7683
2014-09-30
6
3
310
321
514605
Implementing the New First and Second Differentiation of a General Yield Surface in Explicit and Implicit Rate-Independent Plasticity
F Moayyedian
1
M Kadkhodayan
kadkhoda@um.ac.ir
2
Mechanical Engineering Department, Ferdowsi University of Mashhad
Mechanical Engineering Department, Ferdowsi University of Mashhad
In the current research with novel first and second differentiations of a yield function, Euler forward along with Euler backward with its consistent elastic-plastic modulus are newly implemented in finite element program in rate-independent plasticity. An elastic-plastic internally pressurized thick walled cylinder is analyzed with four famous criteria including both pressure dependent and independent. The obtained results are in good agreement with experimental results. The consistent/continuum elastic-plastic moduli for Euler backward method are also investigated.
http://jsm.iau-arak.ac.ir/article_514605_2bbbb3fae98631fb7466354876bf9cac.pdf
Rate-independent Euler backward/forward methods
Consistent elastic-plastic modulus
Internally pressurized thick walled cylinder
eng
Islamic Azad University Arak Branch
Journal of Solid Mechanics
2008-3505
2008-7683
2014-09-30
6
3
322
333
514606
New Method of Determination for Pressure and Shear Frictions in the Ring Rolling Process as Analytical Function
M.R Zamani
mrzamani@alum.sharif.edu
1
Mechanical Engineering Department, Sharif University of Technology
Ring rolling is one of the most significant methods for producing rings with highly precise dimensions and superior qualities such as high strength uniformity, all accomplished without wasting any materials. In this article, we have achieved analytical formulas for calculating the pressure and shear friction over the contact arcs between the rollers and ring in the ring rolling process for the material in general nonlinear hardening property. We have also asserted the best mathematical model to predict friction for rolling processes. The method we use is based on calculating the analytical stress distribution. In other words, by using of Saint-Venan principal the stress components are calculated as analytical functions. Once that is accomplished, the pressure and shear traction over the rollers are able to be analyzed. The crucial characteristics which set apart this study from other studies are the investigation of the effects of the speed with which rollers are fed, and resulting ring velocity. With normal and shear friction, those characteristics cannot be investigated by other methods such as the slab method, upper bound, etc. Also, results show the effects of material hardening properties, radius of rollers and thickness reduction under pressure, and shear friction distributions.
http://jsm.iau-arak.ac.ir/article_514606_affcb43e424f07620ec1975d9f4d1465.pdf
Ring rolling process
Analytical solution for pressure and shear tractions
Nonlinear material
Friction model