2016
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Strain Analysis by Digital Shearography on an Aluminium Plate with a Geometric Defect under Thermal Loading
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Digital shearography is a nondestructive and noncontact method for strainmeasurement. In this article strain analysis on defected plate has been studied by the digital shearography method along with a new technique for phase map measurement. For this purpose, an optical setup known as modified Michelson interferometry system with two diode lasers were developed which are used as coherent optical source. To create phase shifting a piezoelectrical ceramic was used to miniature displacements of interferometry. Phase shifting technique was used to measure phases and differences between the phases.The strain was measured using the experimental method and compared with numerical analysis results. Behavior of two graphs of experimental measurement and numerical analysis was approximately the same.
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7


R.
Moharrami
Mechanical Engineering Department, University of Zanjan, Iran.
Mechanical Engineering Department, University
Iran
r_moharami@znu.ac.ir


M.J.
Taghiloo
Mechanical Engineering Department, University of Zanjan, Iran.
Mechanical Engineering Department, University
Iran
mohammadjavad@znu.ac.ir


A.
Darudi
Mechanical Engineering Department, University of Zanjan, Iran.
Mechanical Engineering Department, University
Iran
darudi@znu.ac.ir
Strain measurement
Phase calculation
Digital shearography
Geometric defect
[[1] B. Bhaduri, M.P. Kothiyal, N. Krishna Mohan, Digital speckle pattern interferometry (DSPI) with increased sensitivity: Use of spatial phase shifting, Opt. Commun. 272 (2007) 914.##[2] B. Bhaduri, N. Krishna Mohan, M.P. Kothiyal, Use of spatial phase shifting technique in digital speckle##pattern interferometry (DSPI) and digital shearography (DS), Opt. Express. 14(24) (2006) 1159811607.##[3] P.K. Rastogi, Digital Speckle Pattern Interferometry and Related Techniques, John Wiley and Sons Ltd., New York, 2001.##[4] S. Wu, L. Zhu, Q. Feng, L. Yang, Digital shearography with in situ phase shift calibration, Opt. Laser.##Eng. 50 (2012) 12601266.##[5] Ch. Cai, L. He, Improved MachZehnder interferometerbased shearography, Opt. Laser. Eng. 50 (2012) 16991705 .##[6] A. Albertazzi, M. Viotti, M. Kapp, A radial Inplane DSPI interferometer using diffractive optics for residual stress measurement. In: Ninth International Symposium on Laser Metrology, 2008 Bellingham, (715525171552510).##[7] W. Steinchen, L. Yang, Digital Shearography: Theory and Application of Digital Speckle Pattern Shearing Interferometer, SPIE Press, Washington, (2003).##[8] D.V. Nelson, Residual stress determination by hole drilling combined with cptical methods, Measurement, SEM, (2010).##]
Creep Analysis of the FGM Cylinder under Steadystate Symmetric Loading
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2
In this paper, a semianalytical method for creep investigation and elastic behavior of FGM rotary cylinders has been introduced. Assumed cylinder was divided to numerous finite width layers with constant thermodynamic properties in each layer. Governing equations converted to ordinary differential equations with constant coefficients by applying continuity conditions between layers and boundary conditions of disc in derived equations, then these equations could be solved by a prepared computer code. For thermoelastic part, variation of dimensionless radial and circumferential strains versus dimensionless radius investigated for several power of FGM material. Also, verification of results was done. For creep part, variation of dimensionless radial and circumferential strain rates versus dimensionless radius was studied for different temperatures and limited timeframe. Changes of radial and circumferential strain rates versus radius were investigated and the results were validated. Finally, the effects of various parameters on creep behavior of rotary cylinder in several examples was examined.
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N.
Habibi
Mechanical Engineering Department, University of Kurdistan, Iran.
Mechanical Engineering Department, University
Iran
n.habibi@uok.ac.ir


S.
Samawati
Mechanical Engineering Department, Khajeh Nasir Toosi University of Technology, Iran.
Mechanical Engineering Department, Khajeh
Iran
sadi.2686@yahoo.com


O.
Ahmadi
Mechanical Engineering Department, Urmia University, Iran.
Mechanical Engineering Department, Urmia
Iran
omidahmadi965@yahoo.com
Exact Solution
Rotary Cylinder
creep
Navier Equation
[[1] M. Koizumi, Concept of FGM, Ceramic. Trans. 34 (1993) 310.##[2] S.B. Singh, S. Ray, Creep analysis in an isotropic FGM rotating disc of AlSic composite, J. Mate. Process. Tech. 143(1) (2003) 616622.##[3] S.B. Singh, S. Ray, Modeling the anisotropy and creep in orthotropic aluminumsilicon carbide composite rotating disc, J. Mech. Mater. 34 (2002) 363372.##[4] S. Huishen, Post buckling analysis of axial loaded functionally graded cylindrical panels in thermal environments. Int. J. Solids. Struc. 39 (2002) 5991##[5] L.P. Jacob, Thermoelastic analysis and optimization of functionally graded plates and shells, MSc Thesis, USA: Maine University, 2003.##[6] K.M. Liew, S. Kitipornchai, X.Z. Zhang, C.W. Lim, Analysis of the thermal stress behavior of functionally graded hollow circular cylinders. Int. J. Solids.##Struct. 40 (2003) 23552380.##[7] T. Singh, V.K. Gupta, Effect of anisotropy on steady state creep in functionally graded cylinder, Compos. Struct. 93(2) (2011) 747758.##[8] J.F. Durodola, O. Attia, Deformation and stresses in FG rotating disks. Compos. Sci. Technol. 60(2000) 987995.##[9] A. Loghman, V. Atabakhshian, Semianalytical Solution for Timedependent creep analysis of rotating cylinders made of anisotropic exponentially graded material (EGM), J. Solid. Mech. 4(3) (2012) 313326.##[10] M. Ghannad, G.H. Rahimi, M. ZamaniNejad, Elastic analysis of pressurized thick cylindrical shells with variable thickness made of functionally##graded materials, Composites. 45 (2013) 388396.##[11] M. ZamaniNejad, M.D. Kashkoli, Timedependent thermocreep analysis of rotating FGM thickwalled cylindrical pressure vessels under heat ux. Int. J. Eng. Sci. 82 (2014) 222237.##[12] M. ZamaniNejad, M. Jabbari, M. Ghannad, Elastic analysis of FGM rotating thick truncated conical shells with axiallyvarying properties under##nonuniform pressure loading. Compos. Struct. 122 (2015) 561569.##[13] M. ZamaniNejad, M. Jabbari, M. Ghannad, Elastic analysis of axially functionally graded rotating thick cylinder with variable thickness under nonuniform arbitrarily pressure loading. Int. J. Eng. Sci. 89 (2015) 8699.##[14] M. ZamaniNejad, M. Jabbari, M. Ghannad, Elastic analysis of rotating thick cylindrical pressure vessels under nonuniform pressure: Linear and##nonlinear thickness. Period. Polytech. Mech. 59(2) (2015) 65.##[15] M. Jabbari, M. ZamaniNejad, M. Ghannad, Thermoelstic analysis of axially functionally graded rotating thick cylindrical pressure vessels with variable thickness under mechanical loading, Int. J. Eng. Sci. 96 (2015) 118.##[16] A. Loghman, H. Shayestemoghadam, MagnetoThermoMechanical creep behavior of nanocomposite rotating cylinder made of polypropylene reinforced by MWCNTS, J. Theor. App. Mechpol. 54 (2011) 239249.##[17] M. Garg, B.S. Salaria, V.K. Gupta, Modeling creep in a variable thickness rotating FGM disc under varying thermal gradient, Eng. Computations. 32 (2015) 1230 1250.##[18] A. Hassani, M.H. Hojjati, G.H. Farrahi, R.A. Alashti, Semiexact solution for thermomechanical analysis of functionally graded elasticstrain hardening rotating disks. Commun. Nonlinear Sci. Numer. Simul. 17(9) (2012) 37473762.##[19] M. Garg, B.S. Salaria, V.K. Gupta, Effect of disc geometry on the steadystate creep in a rotating disc made of functionally graded material. Mater.##Sci. Forum (2013) 183191.##[20] K. Khanna, V.K. Gupta, S.P. Nigam, Creep analysis of a variable thickness rotating FGM disc using Tresca Criterion, defence. Sci. J. 65 (2015) 163170.##[21] S.A. Hosseini Kordkheili, R. Naghdabadi, Thermoelastic analysis of functionally graded rotating disk, Compos. Struct. 79 (2007) 508516.##]
Elasticity Solution for Static Analysis of Sandwich Structures with Sinusoidal Corrugated Cores
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Metal sandwich panels are threedimensional structures widely used in industries mainly due to two distinct properties: low density and high strength. Although significant efforts have been made at research into corrugated sandwich panels, analytical solutions are still very few. This work wishes to present accurate analytical results of static analysis of corrugated sandwich panels. In order to determine equivalent properties of corrugated core in the thickness direction, energy method is used in conjunction with homogenization approach. Based on threedimensional theory of elasticity, partial differential equations are reduced to ordinary differential equations by using the Fourier series. Analytical solutions for the stress and displacement fields are derived by using the statespace method in the thickness direction.A detailed parametric study was conducted involving the dependency of outofplane properties on the corrugation geometrical parameters. Moreover, effects of these variables on the stress and displacement fields are discussed.
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M.
Shaban
Mechanical Engineering Department, BuAli Sina University, Hamadan, Iran.
Mechanical Engineering Department, BuAli
Iran
m.shaban@basu.ac.ir
Corrugated sandwich panel
Elasticity solution
Statespace
Analytical
Static
[[1] C. Above, R.E. Hubka, Elastic constants for corrugatedcore sandwich plates, NACA Tech. Washington D.C., (1951).##[2] D. Briassoulis, Equivalent orthotropic properties of corrugated sheets, Comput. Struct., Comput. Struct., 23 (1986) 129138.##[3] W.S. Chang, E. Ventsel, T. Krauthammer, J. John, Bending behavior of corrugatedcore sandwich plates, Compos. Struct. 70 (2005) 8189.##[4] N. Buannic, P. Cartraud, T. Quesnel, Homogenization of corrugated core sandwich panels, Compos. Struct. 59 (2003) 299312.##[5] Y. Xia, M.I. Friswell, E.I.S. Flores, Equivalent models of corrugated panels, Int. J. Solids. Struct. 49 (2012) 14531462.##[6] G. Bartolozzi, M. Pierini, U. Orrenius, N. Baldanzini, An equivalent material formulation for sinusoidal corrugated cores of structural sandwich panels, Compos. Struct. 100 (2013) 173185.##[7] H. Mohammadi, S. ZiaeiRad, I. Dayyani, An equivalent model for trapezoidal corrugated cores based on homogenization method, Compos. Struct. 131 (2015) 160170.##[8] Z. Ye, V.L. Berdichevsky, W. Yu, An equivalent classical plate model of corrugated structures, Int. J. Solids. Struct. 51 (2014) 20732083.##[9] K.J. Park, K. Jung, Y.W. Kim, Evaluation of homogenized effective properties for corrugated composite panels, Compos. Struct. 140 (2016) 644654.##[10] I. Dayyani, A.D. Shaw, E.I. Saavedra Flores, M.I. Friswell, The mechanics of composite corrugated structures: A review with applications in morphing aircraft, Compos. Struct. 133 (2015) 358380.##]
Finite Element Analysis of a New Specimen for Conducting Fracture Tests under Mixed Mode I/III Loading
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In this paper, a new discshaped specimen containing a tilted crack was proposed so as to conduct fracture tests under mixed mode I/III loading. This specimen was able to produce complete mode mixities, ranging from pure mode I to pure mode III. Many finite element analyses were performed to obtain crack parameters (i.e. stress intensity factors at the crack tip) and geometry factors. It was shown that the mode III was added to the mode I loading as the crack angle changed. Moreover, the crack length as well as position of the lower supports was varied to study loading type at the crack tip. Finally, applicability of the proposed specimen in experimental point of view was considered by performing fracture experiments on the asphalt concrete. The results showed that fracture strength of the asphalt concrete decreases as the proportion of mode III at the crack tip enhances.
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S.
Pirmohammad
Mechanical Engineering Department, Faculty of Engineering, University of Mohaghegh Ardabili, Ardabil, Iran.
Mechanical Engineering Department, Faculty
Iran
s_pirmohammad@uma.ac.ir


A.
Bayat
Mechanical Engineering Department, Faculty of Engineering, University of Mohaghegh Ardabili, Ardabil, Iran.
Mechanical Engineering Department, Faculty
Iran
Mixed mode I/III
Cracked disc specimen
Fracture strength
Asphalt concrete
[[1] S. Pirmohammad, M.R. Ayatollahi, Fracture resistance of asphalt concrete under different loading modes and temperature conditions, Constr. Build. Mater. 53 (2014) 235242.##[2] M.R.M. Aliha, H. Behbahani, H. Fazaeli, M.H. Rezaifar, Study of characteristic specification on mixed mode fracture toughness of asphalt mixtures, Constr. Build. Mater. 54 (2014) 623635.##[3] I. Artamendi, H. AlKhalid, A comparision between beam and semicircular bending fracture tests for asphalt, J. Road. Mater. Pavement. Des. 6 (2006) 163180.##[4] J.R. Yates, R.A. Mohammed, Crack propagation under mixed mode (I+III) loading, Fatigue. Fract. Eng. M. 19 (1996) 12851290.##[5] V.E. Lazarus, J.B. Leblond, S.E. Mouchrif, Crack front rotation and segmentation in mixed mode I + III or I + II + III. Part II: Comparison with experiments, J. Mech. Phis. Solids. 41 (2001) 14211443.##[6] T. Fett, G. Gerteisen, S. Hahnenberger, G. Martin, D. Munz, Fracture tests for ceramics under modeI, modeII and mixedmode loading, J. Eur. Ceram. Soc. 15 (1995) 307312.##[7] G.S. Xeidakis, I.S. Samaras, D.A. Zacharopoulos, G.E. Papakalitakis, Crack growth in a mixedmode loading on marble beams under three point bending, Int. J. Fracture. 79 (1996) 197208.##[8] K.P. Chong, M.D. Kuruppu, J.S. Kuszmual, Fracture toughness determination of layered materials, Eng. Fract. Mech. 28 (1987) 4354.##[9] M.R. Ayatollahi, M.R.M. Aliha, M.M. Hasani, Mixed mode brittle fracture in PMMA  an experimental study using SCB specimens, Mater. Sci. Eng. 417 (2006) 348356.##[10] S.H. Chang, C.L. Lee, S. Jeon, Measurement of rock fracture toughness under modes I and II and mixedmode conditions by using disctype specimen, Eng. Geol. 66 (2002) 7997.##[11] M.R.M. Aliha, M.R. Ayatollahi, R. Ashtari, Mode I and mode II fracture toughness testing for a coarse grain marble, Appl. Mech. Mater. 56 (2006) 181188.##[12] G.C. Sih, Strainenergydensity factor applied to mixed mode crack problems, Int. J. Fracture. 10 (1974) 305321.##[13] M.A. Hussain, S.L. Pu, J. Underwood, Strain energy release rate for a crack under combined mode I and mode II, Fracture analysis ASTM STP 560. Philadelphia: American Society for Testing and Materials, (1974) 228.##[14] M.R. Ayatollahi, H. Abbasi, Prediction of fracture using a strain based mechanism of crack growth, Build. Res. J. 49 (2001) 167180.##[15] M. Ameri, A. Mansourian, M. Heidary Khavas, M.R.M. Aliha, M.R. Ayatollahi, Cracked asphalt pavement under traffic loading  A 3D finite element analysis, Eng. Fract. Mech. 78 (2011) 18171826.##[16] M.R. Ayatollahi, S. Pirmohammad, K. Sedighiani, Threedimensional finite element modeling of a transverse topdown crack in asphalt concrete, Comput. Concrete. 13 (2014) 569585.##[17] L.P. Pook, The fatigue crack direction and threshold behaviour of mild steel under mixed mode I and III loading, Int. J. Fatigue. 7 (1985) 2130.##[18] H.F. Li, C.F. Qian, Experimental study of I + III mixed mode fatigue crack transformation propagation, Fatigue. Fract. Eng. M. 34 (2011) 5359.##[19] X. Feng, A.M. Kumar, J.P. Hirth, Mixed mode I/III fracture toughness of 2034 aluminum alloys, Acta. Metall. Mater. 41 (1993) 27552764.##[20] Z. Wei, X. Deng, M.A. Sutton, J. Yan, C.S. Cheng, P. Zavattieri, Modeling of mixedmode crack growth in ductile thin sheets under combined inplane and outofplane loading. Eng. Fract. Mech. 78 (2011) 30823101.##[21] S.V. Kamat, M. Srinivas, R.P. Rama, Mixed mode I/III fracture toughness of Armco iron, Acta. Mater. 46 (1998) 49854992.##[22] M.R.M. Aliha, A. Bahmani, Sh. Akhondi, Numerical analysis of a new mixed mode I/III fracture test specimen, Eng. Fract. Mech. 134 (2015) 95110.##[23] D. Tim, B. Birgisson, D. Newcomb, Development of mechanisticempirical pavement design in Minnesota, J. Tran. Res. Rec. 1629 (1998) 181188.##[24] M.R.M. Aliha, A. Bahmani, Sh. Akhondi, A novel test specimen for investigating the mixed mode I+ III fracture toughness of hot mix asphalt compositesExperimental and theoretical study, Int. J. Solids. Struct. 90 (2016) 167177.##[25] M. Ameri, A. Mansourian, S. Pirmohammad, M.R.M. Aliha, M.R. Ayatollahi, Mixed mode fracture resistance of asphalt concrete mixtures, Eng. Fract. Mech. 93 (2012) 153167.##]
An Investigation to Nonlinear Elastic Behavior of Pericardium Using Uniaxial Tensile Test
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2
In this paper, the nonlinear elastic behavior of pericardium of human, canine, calf and ostrich was studied. For this purpose, the mechanical behavior was investigated from two viewpoints of the Cauchy and Green elastic materials.Firstly, the experimental data were fitted by Cauchy elastic stress equation. The results showed that the response of Cauchy elastic materials was not fitted with the experimental data appropriately. Secondly, the Green elastic materials were studied by assuming strain energy functions for the mechanical response of the samples. For this purpose, the exponentialexponential, power lawpower law, and exponentialpower law energy functions were investigated by mathematical programming. It was observed that all energy functions were fitted with the experimental data accurately, especially the power lawpower law function. Finally, it was observed that the Green elastic materials theory was more appropriate for studying the mechanical behavior of pericardium by comparing the experimental and theoretical results.
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M.
Arman
Department of Materials Science and Engineering, K. N. Toosi University of Technology, Tehran, Iran.
Department of Materials Science and Engineering,
Iran
m.arman.mfe@gmail.com


K.
Narooei
Department of Materials Science and Engineering, K. N. Toosi University of Technology, Tehran, Iran.
Department of Materials Science and Engineering,
Iran
knarooei@kntu.ac.ir
Pericardium
Nonlinear elastic behavior
Strain energy function
Green material
Cauchy material
[[1] R.V. Noort, S.P. Yates, T.R.P. Martin, A.T. Barker, M.M. Black, A study of the effects of glutaraldehyde and formaldehyde on the mechanical behaviour of bovine pericardium, Biomaterials. (1982) 2126.##[2] P.H. Chew, F.S.P. Yin, S.L. Zeger, Biaxial Stressstrain Properties of Canine Pericardium, J. Mol. Cell. Cardiol. (1986) 567578.##[3] M.M. Maestro, J.O.N. Turnay, P. Fernandez, D. Suarez, J.M.G. Paez, S. Urillo, M.A. Lizarbe, E. JorgeHerrero, Biochemical and mechanical behavior of ostrich pericardium as a new biomaterial, Acta. Biomater. 2 (2006) 213219.##[4] E. Daar, E. Woods, J.L. Keddie, A. Nisbet, D. A. Bradley, Effect of penetrating ionising radiation on the mechanical properties of pericardium, Nucl. Instrum. Methods. 619 (2010) 356360.##[5] J. M.G. Paez, E.J. Herrero, A.C. Sanmartin, I. Millan, A. Cordon, M.M. Maestro, A. Rocha, B. Arenaz, J.L. CastilloOlivares, Comparison of the mechanical behaviors of biological tissues subjected to uniaxial tensile testing: pig, calf and ostrich pericardium sutured with GoreTex, J. Biomaterials. 24 (2003) 16711679.##[6] R. Claramunt, J.M.G. Paez, L. Alvarez, A. Ros, M.C. Casado, Fatigue behaviour of young ostrich pericardium, Mater. Sci. Eng. (2012) 14151420.##[7] D. Cohn, H. Younes, E. Milgarter, G. Uretzky, Mechanical behaviour of isolated pericardium: species, isotropy, strain rate and collagenase effect on pericardium tissues, J. Clin. Mater. (1987) 115124.##[8] P. Zioupos, J.C. Barbenel, Mechanics of native bovin pericardium, J. Biomaterials. (1994) 374382.##[9] J.M. Lee, D.R. Boughner, Mechanical properties of human pericardium. Differences in viscoelastic response when compared with canine pericardium., Circ. Res. (1985) 475481.##[10] N. Gundiah, M.B. Ratcliffe, L.A. Pruitt, Determination of strain energy function for arterial elastin: Experiments using histology and mechanical tests, J. Biomech. (2007) 586594.##[11] M.A. Zulliger, P. Fridez, K. Hayashi, N. Stergiopulos, A strain energy function for arteries accounting for wall composition and structure, J. Biomech. (2004) 9891000. ##[12] M.A. Zulliger, N. Stergiopulos, Structural strain energy function applied to the ageing of the human aorta, J. Biomech. (2007) 30613069.##[13] S.G. Kulkarni, X.L. Gao, S.E. Horner, R.F. Martlock, J.Q. Zheng, A transversely isotropic viscohyperelastic constitutive model for soft tissues, Math. Mech. Solids. (2014) 124.##[14] P.G. Pavan, P. Pachera, C. Tiengo, A. Natali, Biomechanical behavior of pericardial human tissue: a constitutive formulation, Inst. Mech. Eng. H. J. Eng. Med. (2014) 926934.##[15] K. Miller, Constitutive modelling of abdominal organs, J. Biomech. (2000) 367373.##[16] Z. Gao, K. Lister, D.J. Desai, Constitutive Modeling of Liver Tissue: Experiment and Theory, Ann. Biomed. Eng. (2010) 505516.##[17] D.Z. Veljkovic, V.J. Rankovic, S.B. Pantovic, M.A. Rosic, M.R. Kojic, Hyperelastic behavior of porcine aorta segment under extensioninflation tests fitted with various phenomenological models, Acta. Bioeng. Biomech. (2014) 3745.##[18] R.W. Ogden, G. Saccomandi, I. Sgura, Fitting hyperelastic models to experimental data, Comput. mech. (2004) 484502.##[19] H. Darijani, R. Naghdabadi, M.H. Kargarnovin, Hyperelastic materials modelling using a strain measure consistent with the strain energy postulates, J. Mech. Eng. Sci. (2010) 591602.##[20] R.W. Ogden, Nonlinear elastic deformation, Dover Publication, 1997.##[21] T. Belytschko, W.K. Liu, B. Moran, Nonlinear finite elements for continua and structures, John Wiley and Sons, LTD, 2000.##[22] H. Darijani, R. Naghdabadi, Hyperelastic materials behavior modeling using consistent strain energy density functions, Acta. Mech. (2010) 235254.##[23] M. Mansouri, H. Darijani, Constitutive modeling of isotropic hyperelastic material in an exponential framework using a selfcontained approach, Int. J. Solids. Struct. (2014) 43164326.##[24] F.J. Carter, T.G. Frank, P.J. Davies, D. Mc Lean, A. Cuschieri, Measurements and modelling of the compliance of human and porcine, Med. Image. Ana. (2001) 231236.##[25] M.W. Lai, E. Krempl, D. Ruben, Introduction to continuum mechanics, Elsevier. (2010).##[26] T. Beda, An approach for hyperelastic modelbuilding and parameters estimation a review of constitutive models, Eur. Polym. J. (2004) 97108.##[27] A.S. Gendy, A.F. Saleeb, Nonlinear material parameter estimation for charcterizing hyperelastic large strain models, Comput. Mech. 25 (2000) 6677.##[28] H. Hosseinzadeh, M. Ghoreishi, K. Narooei, Investigation of hyperelastic models for nonlinear elastic behavior of demineralized and deproteinized bovine cortical femur bone, J. Mech. Behav. Biomed. Mater. 59 (2016) 393403.##]
Improvement in Mechanical Properties of Titanium Deformed by ECAE Process
2
2
In this study, annealed CPTi (Grade 2) was processed by Equal Channel Angular Extrusion (ECAE) up to 2 passes at a temperature of 400◦C following route A with a constant ram speed of 30 mm/min through a die angle of 90◦ between the die channels. Mechanical properties of the extruded materials were obtained at different strain rates. The results indicated that the tensile yield stress and ultimate tensile strength of the extruded specimens increased significantly after 2 passes of ECAE process. The maximum increase for yield stress was around 90% which occurred at the pulling rate of 0.5 mm/min. The bending fatigue life of the extruded specimens improved significantly so that in low cycle fatigue regime a 700% increase in fatigue life was observed after two ECAE passes. The improvement was lower in high cycle fatigue regime. The microhardness measurement of the specimens indicated that the average microhardness of the samples increased about 140% after 2 passes. The fracture mechanism of the ECAE specimens was also studied by fractography of the fracture surface of specimens. Microstructure of the extruded specimens was also examined by optical microscopy.
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64


J.
Nemati
Mechanical Engineering Department, Faculty of Engineering, BuAli Sina University, Hamadan, Iran.
Mechanical Engineering Department, Faculty
Iran
ja_neamati@yahoo.com


S.
Sulaiman
Department of Mechanical and Manufacturing Engineering, University Putra Malaysia, Malaysia.
Department of Mechanical and Manufacturing
Iran
shamsuddin@upm.edu.my


A.
Khalkhali
School of Mechanical Engineering, Islamic Azad University, Takestan Branch, Takestan, Iran.
School of Mechanical Engineering, Islamic
Iran
ata_kh1@yahoo.com
CPTi (Grade2)
ECAE
mechanical properties
Bending fatigue
Microhardness
[[1] ASME I. Properties and Selection: Nonferrous Alloys and SpecialPurpose Materials, ASME Handbook, 2 (1990) 592593.##[2] R. Chaudhari, R. Bauri, Microstructure and Mechanical Properties of Titanium Processed by Spark Plasma Sintering (SPS), Metallurgic Microstructure anu. 3 (2014) 3035.##[3] G. Purcek, O. Saray, O. Kul, I. Karaman, G.G. Yapici, M. Haouaoui, H.J. Maier, Mechanical and wear properties of ultranegrained pure Ti produced by multipass equalchannel angular extrusion, Mater. Sci. Eng. A. 517 (2009) 97104.##[4] V.P. Basavaraj, U. Chakkingal, T.S.P. Kumar, Study of channel, angle inuence on material ow and strain inhomogeneity in equal channel angular pressing using 3D nite element simulation, J. Mater. Process. Tech. 209 (2009) 8995.##[5] I. Kim, J. Kim, D.H. Shin, C.S. Lee, S.K. Hwang, Effects of equal channel angular pressing temperature on deformation structures of pure Ti, Mater. Sci. Eng. 342 (2003) 302310.##[6] Y.W. Tham, M.W. Fu, H.H. Hng, M.S. 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