Islamic Azad University Arak Branch
Journal of Solid Mechanics
2008-3505
2008-7683
5
1
2013
03
30
Plane Wave Propagation Through a Planer Slab
1
13
EN
R
Kakar
Principal, DIPS Polytechnic College, Hoshiarpur
rkakar_163@rediffmail.com
An approximation technique is considered for computing transmission and reflection coefficients for propagation of an elastic pulse through a planar slab of finite width. The propagation of elastic pulse through a planar slab is derived from first principles using straightforward time-dependent method. The paper ends with calculations of enhancement factor for the elastic plane wave and it is shown that it depends on the velocity ratio of the wave in two different media but not the incident wave form. The result, valid for quite arbitrary incident pulses and quite arbitrary slab inhomogeneities, agrees with that obtained by time-independent methods, but uses more elementary methods.
Inhomogeneous media,Plane waves,time-independent methods,Navier’s equations
http://jsm.iau-arak.ac.ir/article_514501.html
http://jsm.iau-arak.ac.ir/article_514501_2cfff4f3854884834a54f6edf14caa64.pdf
Islamic Azad University Arak Branch
Journal of Solid Mechanics
2008-3505
2008-7683
5
1
2013
03
30
Double Cracks Identification in Functionally Graded Beams Using Artificial Neural Network
14
21
EN
F
Nazari
Department of Mechanical Engineering, Ferdowsi University of Mashhad
M.H
Abolbashari
Department of Mechanical Engineering, Lean Production Engineering Research Center, Ferdowsi University of Mashhad
abolbash@um.ac.ir
This study presents a new procedure based on Artificial Neural Network (ANN) for identification of double cracks in Functionally Graded Beams (FGBs). A cantilever beam is modeled using Finite Element Method (FEM) for analyzing a double-cracked FGB and evaluation of its first four natural frequencies for different cracks depths and locations. The obtained FEM results are verified against available references. Furthermore, four Multi-Layer Perceptron (MLP) neural networks are employed for identification of locations and depths of both cracks of FGB. Back-Error Propagation (BEP) method is used to train the ANNs. The accuracy of predicted results shows that the proposed procedure is suitable for double cracks identification detection in FGBs.
Double cracks,Functionally graded beam,Artificial Neural Network,Model analysis
http://jsm.iau-arak.ac.ir/article_514502.html
http://jsm.iau-arak.ac.ir/article_514502_b0e36b0d0b438ca048f1394b28749384.pdf
Islamic Azad University Arak Branch
Journal of Solid Mechanics
2008-3505
2008-7683
5
1
2013
03
30
Flow-Induced Instability Smart Control of Elastically Coupled Double-Nanotube-Systems
22
34
EN
V
Atabakhshian
Department of Mechanical Engineering, Faculty of Engineering, Bu-Ali Sina University
A
Ghorbanpour Arani
Faculty of Mechanical Engineering, University of Kashan---
Institute of Nanoscience & Nanotechnology, University of Kashan
aghorban@kashanu.ac.ir
A.R
Shajari
Faculty of Mechanical Engineering, University of Kashan
S
Amir
Faculty of Mechanical Engineering, University of Kashan
Flow induced vibration and smart control of elastically coupled double-nanotube-systems (CDNTSs) are investigated based on Eringen’s nonlocal elasticity theory and Euler-Bernoulli beam model. The CDNTS is considered to be composed of Carbon Nanotube (CNT) and Boron-Nitride Nanotube (BNNT) which are attached by Pasternak media. The BNNT is subjected to an applied voltage in the axial direction which actuates on instability control of CNT conveying nano-fluid. Polynomial modal expansions are employed for displacement components and electric potential and discretized governing equations of motion are derived by minimizing total energies of the CDNTS with respect to time-dependent variables of the modal expansions. The state-space matrix is implemented to solve the eigen-value problem of motion equations and examine frequencies of the CDNTS. It is found that Pasternak media and applied voltage have considerable effects on the vibration behavior and stability of the system. Also, it is found that trend of figures have good agreement with the other studies. The results of this study can be used for design of CDNTS in nano / Micro -electro-mechanical systems.
Double-nanotube system,Instability smart control,Pasternak media,Conveying nano-fluid
http://jsm.iau-arak.ac.ir/article_514503.html
http://jsm.iau-arak.ac.ir/article_514503_7bf7476674f4b25f4d4e5cf1fb40fbc9.pdf
Islamic Azad University Arak Branch
Journal of Solid Mechanics
2008-3505
2008-7683
5
1
2013
03
30
Thermal Vibration of Composites and Sandwich Laminates Using Refined Higher Order Zigzag Theory
35
46
EN
A
Chakrabarti
Department of Civil Engineering, Indian Institute of Technology
anupam1965@yahoo.co.uk
S.K
Singh
Department of Civil Engineering, School of Engineering, Shiv Nadar University, Dadri
sushilbit@yahoo.co.in
A.H
Sheikh
School of Civil, Environment and Mining Engineering, University of Adelaide,
Vibration of laminated composite and sandwich plate under thermal loading is studied in this paper. A refined higher order theory has been used for the purpose. In order to avoid stress oscillations observed in the implementation of a displacement based finite element, the stress field derived from temperature (initial strains) have been made consistent with total strain field. So far no study has been reported in literature on the thermal vibration problem based on the refined higher order theory using a FE model. Numerical results are presented for thermal vibration problems to study the influence of boundary conditions, ply orientation and plate geometry on the natural frequencies of these structures.
Finite Element,Higher order,Laminated composites,Thermal load
http://jsm.iau-arak.ac.ir/article_514504.html
http://jsm.iau-arak.ac.ir/article_514504_77426ad06a6dec03ca4991b449dea3e5.pdf
Islamic Azad University Arak Branch
Journal of Solid Mechanics
2008-3505
2008-7683
5
1
2013
03
30
An Efficient Co Finite Element Approach for Bending Analysis of Functionally Graded Ceramic-Metal Skew Shell Panels
47
62
EN
G
Taj
Department of Civil Engineering, Indian Institute of Technology
gulshantaj19@yahoo.co.in
A
Chakrabarti
Department of Civil Engineering, Indian Institute of Technology
anupam1965@yahoo.co.uk
In this article, the prominence has been given to study the influence of skew angle on bending response of functionally graded material shell panels under thermo-mechanical environment. Derivation of governing equations is based on the Reddy’s higher-order shear deformation theory and Sander’s kinematic equations. To circumvent the problem of C<sub>1</sub> continuity requirement coupled with the finite element implementation, C<sub>0</sub> formulation is developed. A nine noded isoparametric Lagrangian element has been employed to mesh the proposed shell element in the framework of finite element method. Bending response of functionally graded shell under thermal field is accomplished by exploiting temperature dependent properties of the constituents. Arbitrary distribution of the elastic properties follows linear distribution law which is a function of the volume fraction of ingredients. Different combinations of ceramic-metal phases are adopted to perform the numerical part. Different types of shells (cylindrical, spherical, hyperbolic paraboloid and hypar) and shell geometries are concerned to engender new-fangled results. Last of all, the influence of various parameters such as thickness ratio, boundary condition, volume fraction index and skew angle on the bending response of FGM skew shell is spotlighted. Some new results pertain to functionally graded skew shells are reported for the first time, which may locate milestone in future in the vicinity of functionally graded skew shells.
Functionally graded material,Skew shell,Higher order shear deformation theory,Bending Analysis,Thermal field
http://jsm.iau-arak.ac.ir/article_514505.html
http://jsm.iau-arak.ac.ir/article_514505_12ec09d38c1abd94d076906f62811b86.pdf
Islamic Azad University Arak Branch
Journal of Solid Mechanics
2008-3505
2008-7683
5
1
2013
03
30
A Semi-analytical Approach to Elastic-plastic Stress Analysis of FGM Pressure Vessels
63
73
EN
A.T
Kalali
Mechanical Engineering Department, Ferdowsi University of Mashhad
S
Hadidi-Moud
Mechanical Engineering Department, Ferdowsi University of Mashhad
hadidi@um.ac.ir
An analytical method for predicting elastic–plastic stress distribution in a cylindrical pressure vessel has been presented. The vessel material was a ceramic/metal functionally graded material, i.e. a particle–reinforcement composite. It was assumed that the material’s plastic deformation follows an isotropic strain-hardening rule based on the von-Mises yield criterion, and that the vessel was under plane-stress conditions. The mechanical properties of the graded layer were modelled by the modified rule of mixtures. By assuming small strains, Hencky’s stress–strain relation was used to obtain the governing differential equations for the plastic region. A numerical method for solving those differential equations was then proposed that enabled the prediction of stress state within the structure. Selected finite element results were also presented to establish supporting evidence for the validation of the proposed analytical modelling approach. Similar analyses were performed and solutions for spherical pressure made of FGMs were also provided.
Functionally graded material,Elastic–plastic analysis,Pressure vessel,Modified rule of mixtures
http://jsm.iau-arak.ac.ir/article_514506.html
http://jsm.iau-arak.ac.ir/article_514506_a776e5e9e434acb76871ef708d94121a.pdf
Islamic Azad University Arak Branch
Journal of Solid Mechanics
2008-3505
2008-7683
5
1
2013
03
30
Axi-Symmetric Deformation Due to Various Sources in Saturated Porous Media with Incompressible Fluid
74
91
EN
R
Kumar
Department of Mathematics, Kurukshetra University
rajneesh_kuk@rediffmail.com
S
Kumar
Department of Mathematics, Govt. Degree College Indora (Kangra), Himachal Pradesh
M.G
Gourla
Department of Mathematics, Himachal Pradesh University
The general solution of equations of saturated porous media with incompressible fluid for two dimensional axi-symmetric problem is obtained in the transformed domain. The Laplace and Hankel transforms have been used to investigate the problem. As an application of the approach concentrated source and source over circular region have been taken to show the utility of the approach. The transformed components of displacement, stress and pore pressure are obtained. Numerical inversion technique is used to obtain the resulting quantities in physical domain. Effect of porosity is shown on the resulting quantities. A particular case of interest is also deduced from the present investigation.
Axi-symmetric,Incompressible porous medium,Pore pressure,Laplace transform,Hankel transform,Concentrated source and source over circular region
http://jsm.iau-arak.ac.ir/article_514507.html
http://jsm.iau-arak.ac.ir/article_514507_12019cd4a97f686eced1774abbba45be.pdf
Islamic Azad University Arak Branch
Journal of Solid Mechanics
2008-3505
2008-7683
5
1
2013
03
30
Vibration and Stability Analysis of a Pasternak Bonded Double-GNR-System Based on Different Nonlocal Theories
92
106
EN
A
Ghorbanpour Arani
Faculty of Mechanical Engineering, University of Kashan---
Institute of Nanoscience & Nanotechnology, University of Kashan
aghorban@kashanu.ac.ir
R
Kolahchi
Faculty of Mechanical Engineering, University of Kashan
H
Vossough
Faculty of Mechanical Engineering, University of Kashan
M
Abdollahian
Faculty of Mechanical Engineering, University of Kashan
This study deals with the vibration and stability analysis of double-graphene nanoribbon-system (DGNRS) based on different nonlocal elasticity theories such as Eringen's nonlocal, strain gradient, and modified couple stress within the framework of Rayleigh beam theory. In this system, two graphene nanoribbons (GNRs) are bonded by Pasternak medium which characterized by Winkler modulus and shear modulus. An analytical approach is utilized to determine the frequency and critical buckling load of the coupled system. The three vibrational states including out-of-phase vibration, in-phase vibration and one GNR being stationary are discussed. A detailed parametric study is conducted to elucidate the influences of the small scale coefficients, stiffness of the internal elastic medium, mode number and axial load on the vibration of the DGNRS. The results reveal that the dimensionless frequency and critical buckling load obtained by the strain gradient theory is higher than the Eringen's and modified couple stress theories. Moreover, the small scale effect in the case of in-phase vibration is higher than that in the other cases. This study might be useful for the design of nano-devices in which GNRs act as basic elements.
GNR,Strain gradient theory,Rayleigh beam theory,Coupled system,Modified couple stress theory
http://jsm.iau-arak.ac.ir/article_514508.html
http://jsm.iau-arak.ac.ir/article_514508_ed6948f5ca0ad58d2dd2d6d44e1431ee.pdf