2014
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Static analysis of rectangular nanoplates using exponential shear deformation theory based on strain gradient elasticity theory
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2
In this research, the bending analysis of rectangular nanoplates subjected to mechanical loading is investigated. For this purpose, the strain gradient elasticity theory with one gradient parameter is presented to study the nanoplates. From the best knowledge of authors, it is the first time that the exponential shear deformation formulation based on strain gradient elasticity theory is carried out. An analytical solution for static analysis of rectangular plates is obtained to solve the governing equations and boundary conditions. The suggested model is justified by a very good agreement between the results given by the present model and available data. Additionally, the effects of different parameters such as internal length scale parameter, length to thickness ratio and aspect ratio on the numerical results are also investigated. It is hoped that the present methodology lead to other models for static and dynamic analysis of rectangular nano structures with considering small scale effects.
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M.R.
Nami
School of Mechanical Engineering, Shiraz University, Shiraz, Iran
School of Mechanical Engineering, Shiraz
Iran
nami@shirazu.ac.ir


M.
Janghorban
School of Mechanical Engineering, Shiraz University, Shiraz, Iran
School of Mechanical Engineering, Shiraz
Iran
maziar.janghorban@gmail.com
Static analysis
Exponential shear deformation theory
Strain gradient elasticity theory
Small scale effects
Nanoplates
[[1] E. Ghavanloo and S. A. Fazelzadeh, Free vibration analysis of orthotropic doublycurved shallow shells based on the gradient elasticity. Composite: Part B, 45 (2013) 1448–1457. ##[2] X. L. Gao and S. K. Park, Variational formulation of a simplified strain gradient elasticity theory and its application to a pressurized thickwalled cylinder problem, International Journal of Solids and Structures, 44 (2007) 74867499. ## [3] S. Ramezani, A micro scale geometrically nonlinear Timoshenko beam model based on strain gradient elasticity theory, International Journal of NonLinear Mechanics, 47 (2012) 863873. ## [4] F. Daneshmand, M. Rafiei, S. R. Mohebpour and M. Heshmati, Stress and straininertia gradient elasticity in free vibration analysis of single walled carbon nanotubes with first order shear deformation shell theory, Applied Mathematical Modelling 37 (2013) 79838003. ##[5] A. Ashoori Movassagh and M. J. Mahmoodi, A microscale modeling of Kirchhoff plate based on modified straingradient elasticity theory, European Journal of Mechanics A/Solids, 40 (2013) 5059. ##[6] C. Polizzotto, A second strain gradient elasticity theory with second velocity gradient inertia – Part I: Constitutive equations and quasistatic behavior, International Journal of Solids and Structures 50 (2013) 37493765. ## [7] S. Sahmani and R. Ansari, On the free vibration response of functionally graded higherorder shear deformable microplates based on the strain gradient elasticity theory, Composite Structure 95 (2013) 430442. ##[8] B. Zhang, Y. He, D. Liu, Z. Gan and L. Shen, A novel sizedependent functionally graded curved mircobeam model based on the strain gradient elasticity theory, Composite Structure 106 (2013) 374392. ##[9] D. Yi, T. C. Wang and S. Chen, New strain gradient theory and analysis. Acta Mechanica Solida Sinica 22 (2009) 4552. ## [10] B. Akgöz and O. Civalek, Application of strain gradient elasticity theory for buckling analysis of protein microtubules, Current Applied Physics 11 (2011) 11331138. ##[11] E. C. Aifantis and H. Askes, Gradient elasticity and flexural wave dispersion in carbon nanotubes, Physics Review B, 80 (2009) 195412. ##[12]S. PapargyriBeskou and D. E. Beskos, Static, stability and dynamic analysis of gradient elastic flexural Kirchhoff plates, Archive of Applied Mechanics 78 (2008) 625–635. ## [13]A. S. Sayyad and Y. M. Ghugal, Buckling analysis of thick isotropic plates by using exponential shear deformation theory, Applied Computer Mechanics 6 (2012) 185–196. ## [14]M. H. Sadd. Elasticity, Theory, Applications, and Numerics. Elsevier (2009). ## [15] K. A. Lazopoulos and A. K. Lazopoulos, Strain gradient elasticity and stress fibers, Archive of Applied Mechanics 83 (2013) 13711381. ##]
The Relationship between Constant Friction Factor and Coefficient of Friction in Metal Forming using Finite Element Analysis
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2
Frictional shear stress is usually determined by utilizing the coefficient of friction or the constant friction factor models. The present study deals with finite element analysis of double cup extrusion process to determine the relationship between constant friction factor (m) and coefficient of friction (µ), since the metal flow in this process is very sensitive to frictional conditions. Therefore, the Finite ElementCode Deform 2D is used which is capable of utilizing both µ and m. According to this analysis a new equation between constant friction factor (m) and coefficient of friction (µ) is suggested. Moreover, in order to evaluate the suggested equation and to compare it with the pervious relationship, finite element analysis of barrelcompression test is carried out. Finite element results indicate that the new equation can accurately predict the relation between m and its equivalent μ value. The importance of converting these factors to each other is specially highlighted to introduce the frictional conditions in some professional and commercial finite element softwares.
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22


Sh.
Molaei
Department of Materials Science and Engineering, School of Engineering, Shiraz University, Shiraz, Iran.
Department of Materials Science and Engineering,
Iran
shivamolaei5@gmail.com


M.
Shahbaz
Department of Materials Science and Engineering, School of Engineering, Shiraz University, Shiraz, Iran.
Department of Materials Science and Engineering,
Iran
mehredads1@gmail.com


R.
Ebrahimi
Department of Materials Science and Engineering, School of Engineering, Shiraz University, Iran.
Department of Materials Science and Engineering,
Iran
ebrahimy@shirazu.ac.ir
Metal Forming
Friction Coefficient
Constant Friction Factor
finite element analysis
The Effect of Fe Additive on Plastic Deformation for CrushBoxes with ClosedCell Metal Foams, Part II: AlComposite FoamFilled brass tubes Compression Response
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2
The brass tubes with foam cores of AlSi7SiC3, AlSi7SiC3Fe1 and AlSi7SiC3Fe3 were produced as the crushboxes with circle and square crosssection. Then axial compressive behavior and energy absorption capability of the foamfilled tubes were investigated during the quasistatic progressive plastic buckling. The uniaxial compressive stress–strain curves of the foamfilled brass tubes exhibited that the compressive stress rose smoothly with the increase of the strain and no stress oscillations occurred in the plastic deformation region throughout the tests. The yield stress and the elastic modulus of the foamfilled brass tubes slightly decreased with increasing of the Fe wt. % in the foam cores. Also, with increasing of the Fe powder from 1wt. % to 3wt. %, the absorption energy of the foamfilled brass tubes decreased slightly dependent on the tubes crosssection. The strainhardening exponent of the tubes with the Al7Si3SiC(+Fe) foam cores were found to be lower than the tubes with the Al7Si3SiC foam cores with no Fe. However, increasing the Fe powder from 1wt. % to 3wt. % caused that the strainhardening to be approximately eliminated and the plastic deformation behavior tends to be approximated to an idealplastic behavior up to the densification strain. Results show all of the compression responses are due to the Micro and Macrodefects within the foams cellular structure as well as the tubes crosssection geometry
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31


S.M.H.
Mirbagheri
Amirkabir university of technology
Amirkabir university of technology
Iran


J.
Khajehali
Amirkabir Univercity
Amirkabir Univercity
Iran
smhmirbagheri@aut.ac.ir
Metal foam
brass tube
plastic buckling
absorption energy
foamfilled tubes
Dynamic recrystallization kinetics of AISI 403 stainless steel using hot compression test
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In this work dynamic recrystallization behavior of AISI 403 martensitic stainless steel was studied using hot compression tests over temperature range of 900 C 1200 C and strain rate range of 0.001 s1  1 s1. The obtained flow curves showed that the hot compression behavior of the alloy is controlled by dynamic recrystallization. The flow stress and strain corresponding to the critical, peak and onset of steady state region were related to the ZenerHollomon parameter using simple power equations. The variation of dynamic recrystallization fraction with strain showed that restoration kinetics is enhanced with increasing temperature and decreasing strain rate. The development of DRX was modeled using Avrami Kinetics equation. The equations proposed by Baragar and CingaraMcQueen were used to develop a new model capable of predicting the flow curves up to the onset of steady state flow region. This work softening is mainly controlled by the phenomenon dynamic recrystallization.
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43


E.
Kevanlo
Department of Materials and Polymer Engineering, Hakim Sabzevari University, Sabzevar, Iran
Department of Materials and Polymer Engineering,
Iran
iman.keyvanlo65@gmail.com


G.R.
Ebrahimi
Sabzevar, Iran
Sabzevar, Iran
Iran
ebrahimi@hsu.ac.ir


S.A.A.
Sani
Department of Materials Science and Engineering, Iran University of Sience and Technology, Tehran, Iran
Department of Materials Science and Engineering,
Iran
saas.mk@gmail.com


A.
Momeni
Department of Materials Science and Engineering, Hamedan University of Technology, Hamedan, Iran
Department of Materials Science and Engineering,
Iran
momeni@hut.ac.ir
Martensitic stainless steel
Dynamic recrystallization
Hot deformation
recrystallization kinetics
Static Strain Aging Behavior of Low Carbon Steel Drawn Wire
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2
The static strain aging is a phenomenon that can change the mechanical properties of low carbon steels. Thus, the static strain aging behavior of low carbon steel wires after drawing process is studied. To do so, the wires are austenitized at different temperatures and cooled in different rates. Then the wires are drawn and aged at a specific temperature and time. Before and after aging of each drawn wire, the hardness distribution at its cross section is measured. The increase in hardness due to aging is called aging index. The results show that the hardness of drawn wire is increased from center to surface of its cross section. However, after aging the hardness is decreased from center to surface. In addition, with increasing the austenitizing temperature, the index is increased. Also, with increasing the cooling rate, the index is decreased. Moreover, the aging index is decreased from center to surface.
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M.
Kazeminezhad
Sharif University of Technology
Sharif University of Technology
Iran
mkazemi@sharif.edu


Y.
Khaledzadeh
sharif University of Technology
sharif University of Technology
Iran
yasharkhaledzadeh@gmail.com


A.
Karimi Taheri
Sharif University of Technology
Sharif University of Technology
Iran
ktaheri@sharif.edu
Static strain aging
Wire drawing
Austenitizing temperature
Cooling rate
hardness
Fabrication of the CuZn multilayer and CuZn alloy by accumulative roll bonding (ARB) with an emphasis on the wear behavior
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2
Accumulative roll bonding (ARB) was used to fabricate the CuZn multilayer and CuZn solid solution. A lamellar structure with the hardness of about 130 VHN was formed after eight ARB cycles. Following to the suitable heat treatment, a solid solution with a uniform microstructure and hardness of about 57 VHN was produced. The dominant wear mechanism in the ARB processed multilayer was found to be delamination and spalling while in the heattreated sample was adhesion. The weight loss of the ARBed multilayer was higher due to the occurrence of spalling and formation of the cracks and cavities during the ARB. On the other hand, the friction coefficient and its undulation were lower, which was contributed to the lubricating effect of Zn and the higher hardness of the ARB processed multilayer. In the heattreated sample, the ability to plastic deformation and the adhesion between the contact surfaces causes the increase in the friction coefficient and its variation.
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M.
Reihanian
Department of Materials Science and Engineering, Faculty of Engineering, Shahid Chamran University, Ahvaz, Iran
Department of Materials Science and Engineering,
Iran
m.reihanian@scu.ac.ir


M.M.
Mahdavian
Islamic Azad University, Ahvaz, Iran
Islamic Azad University, Ahvaz, Iran
Iran
mehdimahdavian@ymail.com


L.
Ghalandari
Islamic Azad University, Shiraz, Iran
Islamic Azad University, Shiraz, Iran
Iran
lghalandari@yahoo.com
Accumulative roll bonding
Multilayer
Solid solution, Microstructure
Wear