Search for: tensile-stress
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    Investigating stage construction in high concrete arch dams

    , Article Indian Journal of Science and Technology ; Volume 8, Issue 14 , July , 2015 ; 09746846 (ISSN) Pourbakhshian, S ; Ghaemian, M ; Sharif University of Technology
    Indian Society for Education and Environment  2015
    Concrete arch dam is a complex geometric structure and designing such a structure requires experience and high knowledge. One of the important parameters in designing concrete arch dams is the tensile stress in arch concrete material. The static analysis results of high arch dam structure depend on structure analysis model, intensively. Stage construction is needed to be focused in modeling high arch dams. In this study, the necessity of considering stage construction in static analysis of dam structure is focused. Modeling stage construction uses Birth and Death technique of elements. Therefore, six stage construction models are provided including applying dam wall weight outright, two... 

    Effect of rolling strain on transformation induced plasticity of austenite to martensite in a high-alloy austenitic steel

    , Article Journal of Materials Processing Technology ; Volume 203, Issue 1-3 , 2008 , Pages 349-354 ; 09240136 (ISSN) Bigdeli Karimi, M ; Arabi, H ; Khosravani, A ; Samei, J ; Sharif University of Technology
    Current studies show a growing interest on transformation induced plasticity (TRIP) in austenitic steels. Most researches are based on inducing plasticity via tensile stresses, so it seems interesting to accomplish these researches by compressive stresses. Rolling process is a suitable choice to make compressive stresses. In present work, the effects of a wide range of rolling strains (5%-60%) at 0 and 24 °C on the austenite to martensite transformation were investigated on high-alloy austenitic steel. For this purpose, XRD, hardness test and magnetic measurements were used. Results show that by increasing the amount of rolling strain, transformation of austenite to martensite generally... 

    Determination of residual stresses in autofrettaged compound tubes for different geometries

    , Article 2007 ASME Pressure Vessels and Piping Conference, PVP 2007, San Antonio, TX, 22 July 2007 through 26 July 2007 ; Volume 5 , 2008 , Pages 53-61 ; 0277027X (ISSN); 0791842835 (ISBN); 9780791842836 (ISBN) Mohammadi, M ; Farrahi, G. H ; Hoseini, S. H ; Sharif University of Technology
    In this paper, using numerical solutions of bore and outer radius hoop residual stresses in various tube geometries for autofrettage prior to shrink fit and shrink fit prior to autofrettage design are investigated, and the results are compared with monobloc autofrettaged and shrunk fit tubes. Both of the former compound tubes induce more compressive bore hoop residual stresses than a monobloc autofrettage and shrunk fit case. Furthermore, in geometries in which maximum bore hoop residual stresses are induced, the outer radius experiences acceptably low tensile residual stresses. Bore hoop residual stresses increase with increase of tube outer radius; however the rate of increasing decreases.... 

    Prediction of effect of thermo-mechanical parameters on mechanical properties and anisotropy of aluminum alloy AA3004 using artificial neural network

    , Article Materials and Design ; Volume 28, Issue 5 , 2007 , Pages 1678-1684 ; 02613069 (ISSN) Forouzan, S ; Akbarzadeh, A ; Sharif University of Technology
    Elsevier Ltd  2007
    An artificial neural network model, using a back-propagation learning algorithm is utilized, to predict the yield stress, elongation, ultimate tension stress, over(R, -) and {divides}ΔR{divides} during hot rolling, cold rolling and annealing of AA3004 aluminum alloy. Input nodes were chosen as the ratio of initial to final thicknesses, reduction, preheating time and temperature, finish rolling temperature and the final annealing temperature. The maximum error for predicted values was 6.35%, the average of absolute relative error was 0.57% and the RMS was 0.00998. It was found that the mechanical properties and anisotropy of AA3004 alloy sheets can be predicted by this approach. © 2006... 

    Stress analysis of three-unit all-ceramic dental bridges using FEM

    , Article 8th Biennial ASME Conference on Engineering Systems Design and Analysis, ESDA2006, Torino, 4 July 2006 through 7 July 2006 ; Volume 2006 , 2006 ; 0791837793 (ISBN); 9780791837795 (ISBN) Biria, M. J ; Farahmand, F ; Shamsaei, N ; Eslami, G. R ; Sharif University of Technology
    Mechanical fracture is a common cause of failure for 3-unit dental bridges, particularly, the all-ceramic structures. The purpose of the present study was to evaluate the effect of convergence angles of the abutments on the distribution of the mechanical stresses, within the prosthesis and at the restoration-abutments interface of a 3-unit all-ceramic bridge. The 3-D geometrical data of the second premolar and first and second molar teeth were obtained using ATOS scanner system and utilized for reconstruction of a surface model of the 3-unit bridge in I-Deas as solid modeler software. This was then transferred to MSC/Nastran software for mesh generation and finite element analysis. Two FE... 

    An FGM coated elastic solid under thermomechanical loading: A two dimensional linear elastic approach

    , Article Surface and Coatings Technology ; Volume 200, Issue 12-13 , 2006 , Pages 4050-4064 ; 02578972 (ISSN) Shodja, H. M ; Ghahremaninejad, A ; Sharif University of Technology
    A thin coating made of linear elastic functionally graded material (FGM) perfectly bonded to an elastic substrate is considered. This work which is of particular interest to tribological community is devoted to the determination of the thermal and mechanical stresses due to mixed normal and tangential Hertzian surface pressure. The thermomechanical properties of the FGM coating are assumed to vary exponentially through the thickness. Solutions for temperature rise and stresses are obtained by use of Fourier transform technique. The influences of coating thickness, Peclet number and friction coefficient on temperature rise and stresses in the FGM coating are investigated. Comparative studies... 

    Room-temperature mechanical properties of dual-phase steels deformed at high temperatures

    , Article Materials Letters ; Volume 59, Issue 14-15 , 2005 , Pages 1828-1830 ; 0167577X (ISSN) Mousavi Anijdan, S. H ; Vahdani, H ; Sharif University of Technology
    Dual-phase steels with different morphology and volume fraction of martensite were deformed between 2% and 8% at a high-temperature range of 150-450 °C. Room-temperature tensile properties showed that both yield and tensile stresses depend on the amount of pre-strain, deformation temperature, volume fraction and morphology of martensite. Results show that both YS and UTS increase with increasing the amount of pre-strain at a given temperature. © 2005 Elsevier B.V. All rights reserved  

    An analytical solution to the elastic-plastic behavior of metal matrix composites under tensile loading

    , Article 29th Congress of the International Council of the Aeronautical Sciences, ICAS 2014 ; 2014 Khosoussi, S ; Mondali, M ; Abedian, A ; Sharif University of Technology
    An analytical approach is proposed for studying the elastic-plastic behavior of short fiber reinforced metal matrix composites under tensile loading. In the proposed method, a micromechanical approach is employed, considering an axi-symmetric unit cell including one fiber and the surrounding matrix. First, the governing equations and the boundary conditions are derived and the elastic solution is obtained based on some shear lag type methods. A plastic deformation is considered for the matrix under each small tensile loading step. Then, applying the successive elastic solutions method, all the plastic strain terms are obtained for the matrix. Thereafter, the elastic-plastic stress transfer... 

    Unidirectional surface waves in bi-anisotropic media

    , Article IEEE Journal of Quantum Electronics ; Volume 54, Issue 6 , 2018 ; 00189197 (ISSN) Karimi, P ; Rejaei, B ; Khavasi, A ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2018
    We show theoretically that unidirectional surface waves can propagate on the surface of homogeneous bi-anisotropic layers with an anti-symmetric chirality tensor. These materials mimic the electromagnetic behavior of an anisotropic medium with gyrotropic permittivity and permeability tensors that operate on pseudo-electromagnetic fields. The unidirectional waves have transverse pseudo-electric or magnetic polarizations and pass through an obstacle without backscattering if the obstacle does not cause polarization change. The bi-anisotropic medium can be realized as a metamaterial comprising omega particles tailored to achieve the constitutive parameters desired. © 2018 IEEE  

    Pre-threaded hole friction stir spot welding of AA2219/PP-C30S sheets

    , Article Journal of Materials Processing Technology ; Volume 273 , 2019 ; 09240136 (ISSN) Paidar, M ; Ojo, O. O ; Moghanian, A ; Karami Pabandi, H ; Elsa, M ; Sharif University of Technology
    Elsevier Ltd  2019
    This paper examines the use of pre-fabricated interlocking arms/threading in enhancing the strength of friction stir spot welded hybrid joints of AA2219/PP-C30S polypropylene polymer by varying parameter combination. The process involves the fabrication of a pre-threaded hole on the Al alloy prior to the joining process, and the threading/crest-pitch profile aids mechanical interlocking. The peak temperature, crest-pitch interlocked profiles, microstructural and mechanical properties of the joints were examined. The results show that an increase in the tool rotational speed increases the thickness of the reaction layer (between the Al and the polymer substrates), the shear-tensile load... 

    Enhancement of bond characteristics of ribbed-surface GFRP bars with concrete by using carbon fiber mat anchorage

    , Article Construction and Building Materials ; Volume 134 , 2017 , Pages 507-519 ; 09500618 (ISSN) Ashrafi, H ; Bazli, M ; Vatani Oskouei, A. V ; Sharif University of Technology
    The bond of fiber-reinforced polymer (FRP) reinforcement is expected to be more sensitive to the strength and geometry of the ribs than conventional steel reinforcement. In this study, the effect of carbon fiber mat anchorage on the pullout behavior of glass fiber-reinforced polymer (GFRP) bars embedded in normal concrete is studied. The studied parameters were the compressive strength of the concrete (16 MPa, 24 MPa, and 37 MPa), and, the length and diameter of the anchorage. In total, 15 variables were studied. Ribbed GFRP bars with 10 mm nominal diameter and 80 mm embedment length, ld, (which is 8 times the bar diameter) were considered. Based on the results for concretes with the... 

    Pulvino and peripheral joint effects on static and seismic safety of concrete arch dams

    , Article Scientia Iranica ; Volume 20, Issue 6 , 2013 , Pages 1579-1594 ; 10263098 (ISSN) Hariri-Ardebili, M. A ; Mirzabozorg, H ; Ghaemian, M ; Sharif University of Technology
    Sharif University of Technology  2013
    One of the methods in limiting tensile stresses in arch dams and removing stress concentrations at the dam-foundation interface is setting the dam body on a concrete saddle called a Pulvino. In the present study, the effects of Pulvino and peripheral joints on the static behavior and seismic performance of arch dams are investigated. Dez Dam with a height of 203 m was selected as a case study and all contraction joints of the dam body were modeled using the discrete crack approach based on as-built drawings. Also, the surrounding rock was modeled as a mass-less medium tied to Pulvino. The dam-reservoirfoundation system was analyzed under static loads accounting for stage construction... 

    Molecular dynamics investigation of β-SiC behavior under three-axial tensile loading

    , Article Journal of Computational and Theoretical Nanoscience ; Volume 8, Issue 11 , 2011 , Pages 2187-2192 ; 15461955 (ISSN) Mortazavi, B ; Simchi, A ; Besharati Givi, M. K ; Rajabpour, A ; Sharif University of Technology
    Molecular dynamics (MD) simulations were used to study the mechanical behaviour of β-SiC at nano-scale under tensile loading. Effects of loading rate and tensile temperature on the mechanical properties and failure were studied. Modified embedded-atom method (MEAM) potential and Berendsen thermostat were utilized for modelling. Periodic boundary conditions were employed and the behaviour of material was analyzed under three-axial loading condition at which the stress- strain relation was acceptably size independent. It is shown that with increasing the loading rate from 5 m/s to 70 m/s, the failure strain increases without a remarkable change in the stress-strain relationship. The MD... 

    A new approach to the elastic–plastic stress transfer analysis of metal matrix composites

    , Article Archive of Applied Mechanics ; Volume 85, Issue 11 , November , 2015 , Pages 1701-1717 ; 09391533 (ISSN) Khosoussi, S ; Mondali, M ; Abedian, A ; Sharif University of Technology
    Springer Verlag  2015
    An analytical approach is proposed for studying the elastic–plastic behavior of short-fiber-reinforced metal matrix composites under tensile loading. In the proposed research, a micromechanical approach is employed, considering an axisymmetric unit cell including one fiber and the surrounding matrix. First, the governing equations and the boundary conditions are derived and the elastic solution is obtained based on some shear-lag-type methods. Since under normal loading conditions and according to the fiber material characteristics, the metal matrix undergoes plastic deformation, while the fiber remains within the elastic region, a plastic deformation is considered for the matrix under each... 

    Comparison between isothermal and non-isothermal fatigue behavior in a cast aluminum-silicon-magnesium alloy

    , Article Strength of Materials ; Volume 47, Issue 6 , November , 2015 , Pages 840-848 ; 00392316 (ISSN) Azadi, M ; Winter, G ; Farrahi, G. H ; Sharif University of Technology
    Springer New York LLC  2015
    In the present study, the out-of-phase thermomechanical fatigue (OP-TMF) behavior of a cast aluminum-silicon-magnesium alloy, the A356.0 alloy which has been widely used in diesel engine cylinder heads, is compared to room-temperature and high-temperature low cycle fatigue (RT-, HT-LCF) behaviors. For this purpose, strain/temperature-controlled isothermal and non-isothermal fatigue tests were performed based on realistic loading conditions in cylinder heads. Fatigue tests results showed that the plastic strain increased during cycles under constant mechanical strain amplitude, while the specimen failed. Under LCF loadings, the cyclic hardening occurred at low temperatures for the A356.0... 

    Compressive behavior of concrete actively confined by metal strips, part B: Analysis

    , Article Materials and Structures/Materiaux et Constructions ; Volume 43, Issue 10 , 2010 , Pages 1383-1396 ; 13595997 (ISSN) Moghaddam, H ; Samadi, M ; Pilakoutas, K ; Sharif University of Technology
    This paper presents analytical part of an investigation on the application of prestressed strips for concrete confinement. In this paper, an analytical model is proposed to predict the compressive stress-strain curve of strapped concrete as a function of the confinement level. The model was calibrated based on the experimental data of compressive tests which were described in part A of this paper. Various parameters are considered in the proposed model including volumetric ratio, yield strength and ultimate strain of confining material, shape of cross section, strength of plain concrete. Three key points were defined on the stress-stress curve of strapped concrete columns and applied in... 

    Optimization of composite patch repair for inclined crack on aluminum plate using genetic algorithm

    , Article 30th Congress of the International Council of the Aeronautical Sciences, ICAS 2016, 25 September 2016 through 30 September 2016 ; 2016 ; 9783932182853 (ISBN) Talebi, B ; Abedian, A ; Firooz, S ; Sharif University of Technology
    International Council of the Aeronautical Sciences  2016
    In this study, a composite patch repair will be designed for an aluminum plate with a central crack placed at 45 degrees to the applied unidirectional tensile load carried by the plate. In this state, the condition of loading is mixed mode. In the first step, behavior of the crack repaired by the composite patch under the applied tensile load is simulated by using ABAQUS commercial software. The crack growth process is modeled with the extended finite element method (XFEM) and the cohesive zone model (CZM) is used to model any damage progression in the adhesive of the composite patch repair. The shape of the five layer composite patch is assumed to be elliptical. For design optimization, the... 

    Role of zinc layer in resistance spot welding of aluminium to steel

    , Article Materials and Design ; Volume 102 , 2016 , Pages 106-114 ; 02641275 (ISSN) Arghavani, M. R ; Movahedi, M ; Kokabi, A. H ; Sharif University of Technology
    Elsevier Ltd  2016
    Effects of zinc layer on microstructure and mechanical behavior of resistance spot welds of aluminum to galvanized (GS-Al joint) and low carbon steel (PS-Al joint) were explored. The results showed that although nugget 'volume' in PS-Al joint was larger, the nugget 'diameters' of PS-Al and GS-Al joints were almost the same in size since the melted zinc layer was pushed toward the outer regions of the nugget. Melting and evaporation of zinc coat led to reduction of Al-Fe intermetallic layer thickness. Presence of zinc also reduced the fixture-induced tensile stress. Utilizing carbon steel fixtures during welding caused a sensible vibration in the joint members. The vibration resulted in... 

    Experimental and numerical investigation of the center-cracked horseshoe disk method for determining the mode I fracture toughness of rock-like material

    , Article Rock Mechanics and Rock Engineering ; Volume 51, Issue 1 , 2018 , Pages 173-185 ; 07232632 (ISSN) Haeri, H ; Sarfarazi, V ; Yazdani, M ; Bagher Shemirani, A ; Hedayat, A ; Sharif University of Technology
    This paper presents a new procedure for determining the fracture toughness of rock-like specimens using the diametric compression test with the center-cracked horseshoe disk (CCHD) method. Using finite element analysis, a dimensionless stress intensity factor was obtained and a formula was rendered for determining mode I fracture toughness. To evaluate the accuracy of the measurement results produced by the CCHD method, fracture toughness experiments were conducted on the same rock-like material using the notched Brazilian disk (NBD) method. The CCHD tests were simulated using a two-dimensional particle flow code for validation of the experimental results, and a great agreement between the... 

    Plasma based surface modication of poly (dimethylsiloxane) electrospun membrane proper for organ-on-a-chip applications

    , Article Scientia Iranica ; Volume 26, Issue 2 , 2019 , Pages 808-814 ; 10263098 (ISSN) Kiyoumarsioskouei, A ; Saidi, M. S ; Moghadas, H ; Firoozabadi, B ; Sharif University of Technology
    Sharif University of Technology  2019
    Electrospun porous membrane; Superhydrophilic surfaces; Superhydrophobic surfaces; Cell culture; Organ on a chip; Flexible membrane; Strong membrane; Surface modications