Search for: thermo-mechanical
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    Metallography and microstructure interpretation of some archaeological tin bronze vessels from Iran

    , Article Materials Characterization ; Vol. 97 , November , 2014 , pp. 74-82 Oudbashi, O ; Davami, P ; Sharif University of Technology
    Archaeological excavations in western Iran have recently revealed a significant Luristan Bronzes collection from Sangtarashan archaeological site. The site and its bronze collection are dated to Iron Age II/III of western Iran (10th-7th century BC) according to archaeological research. Alloy composition, microstructure and manufacturing technique of some sheet metal vessels are determined to reveal metallurgical processes in western Iran in the first millennium BC. Experimental analyses were carried out using Scanning Electron Microscopy-Energy Dispersive X-ray Spectroscopy and Optical Microscopy/Metallography methods. The results allowed reconstructing the manufacturing process of bronze... 

    Modeling of hot isostatic pressing of metal powder with temperature–dependent cap plasticity model

    , Article International Journal of Material Forming ; Volume 6, Issue 3 , September , 2013 , PP. 363-376 Khoei, A. R. (Amir Reza) ; Molaeinia, Z ; Keshavarz, Sh ; Sharif University of Technology
    In this paper, the coupled thermo–mechanical simulation of hot isostatic pressing (HIPing) is presented for metal powders during densification process. The densification of powder is assumed to occur due to plastic hardening of metal particles. The constitutive model developed is used to describe the nonlinear behavior of metal powder. The numerical modeling of hot powder compaction simulation is performed based on the large deformation formulation, powder plasticity behavior, and frictional contact algorithm. A Lagrangian finite element formulation is employed for the large powder deformations. A modified cap plasticity model considering temperature effects is used in numerical simulation... 

    Thermo-mechanical behaviours of light alloys in comparison to high temperature isothermal behaviours

    , Article Materials at High Temperatures ; Vol. 31, issue. 1 , 2014 , pp. 12-17 ; ISSN: 09603409 Azadi, M ; Farrahi, G. H ; Winter, G ; Eichlseder, W ; Sharif University of Technology
    In this article, out-of-phase thermo-mechanical fatigue (TMF) behaviours of light alloys were investigated in comparison to their high temperature low cycle fatigue (LCF) behaviours. For this objective, strain based fatigue tests were performed on the A356 aluminium alloy and on the AZ91 magnesium alloy. Besides, TMF tests were carried out, where both strain and temperature changed. The fatigue lifetime comparison demonstrated that the TMF lifetime was less than that one under LCF loadings at elevated temperatures for both light alloys. The reason was due to severe conditions in TMF tests in comparison to LCF tests. The temperature varied in TMF test but it was constant under LCF loadings.... 

    Friction stir welding of similar and dissimilar aluminium alloys for automotive applications

    , Article International Journal of Automotive and Mechanical Engineering ; Volume 13, Issue 2 , 2016 , Pages 3401-3412 ; 22298649 (ISSN) Selamat, N. F. M ; Baghdadi, A. H ; Sajuri, Z ; Kokabi, A. H ; Sharif University of Technology
    Universiti Malaysia Pahang  2016
    Aluminium alloys are lightweight materials relatively used in automotive industries. However, welding using the conventional welding methods is known to be difficult. In this study, the friction stir welding (FSW) known as the solid state joining process was extensively used for joining similar and dissimilar 5 mm aluminium alloy plates. The butt-joint type of similar joints (AA5083-AA5083) and dissimilar joints (AA5083-AA6061) were carried out under the same welding parameters; 1000 rpm (rotational speed) and 100 mm/min (transverse speed). Macro- and microstructural observations were acquired at the cross-section of the weld regions by stereo and optical microscopes. The microstructural... 

    A new energy-based isothermal and thermo-mechanical fatigue lifetime prediction model for aluminium-silicon-magnesium alloy

    , Article Fatigue and Fracture of Engineering Materials and Structures ; Volume 36, Issue 12 , 2013 , Pages 1323-1335 ; 8756758X (ISSN) Farrahi, G. H ; Azadi, M ; Winter, G ; Eichlseder, W ; Sharif University of Technology
    In this paper, a new fatigue lifetime prediction model is presented for the aluminium-silicon-magnesium alloy, A356.0. This model is based on the plastic strain energy density per cycle including two correction factors in order to consider the effect of the mean stress and the maximum temperature. The thermal term considers creep and oxidation damages in A356.0 alloy. To calibrate the model, isothermal fatigue and out-of-phase thermo-mechanical fatigue (TMF) tests were conducted on the A356.0 alloy. Results showed an improvement in predicting fatigue lifetimes by the present model in comparison with classical theories and also the plastic strain energy density (without any correction... 

    Modeling and experimental study on friction stir welding of artificially aged AA2017 plates

    , Article Materials and Manufacturing Processes ; Volume 28, Issue 6 , 2013 , Pages 683-688 ; 10426914 (ISSN) Mirjalili, A ; Serajzadeh, S ; Jamshidi Aval, H ; Kokabi, A. H ; Sharif University of Technology
    Thermo-mechanical responses, developed microstructure, and mechanical properties in friction stir welding (FSW) of artificially aged AA2017 plates were investigated. A finite element analysis was first employed to evaluate hot deformation behavior of the alloy during welding. Also, hardness, yield strength, and microstructure of the welded alloy were examined using the results of the model and experimental testing. It was found that strain and temperature fields during welding are asymmetrically distributed and the maximum temperature locates in advancing side. Furthermore, considerable grain refinement is observed in the stir zone where recrystallized grains in the range of 3 to 8 m are... 

    Finite element modeling of thermal and mechanical stresses in work-rolls of warm strip rolling process

    , Article Proceedings of the Institution of Mechanical Engineers, Part B: Journal of Engineering Manufacture ; Volume 230, Issue 6 , 2016 , Pages 1076-1086 ; 09544054 (ISSN) Koohbor, B ; Sharif University of Technology
    SAGE Publications Ltd 
    An integrated mathematical model was developed to study the thermo-mechanical behavior of strips and work-rolls during warm rolling process of steels. A two-dimensional finite element analysis was first employed to solve for the thermo-mechanical response of the rolled strip under steady-state conditions. The calculated roll pressure and temperature fields were then used to apply proper boundary conditions for solving the governing thermo-mechanical problem for the work-roll. The obtained results indicate that in warm strip rolling of steels, the thermal and mechanical stresses developed within the work-roll are comparable; however, the more significant influence is due to heating and... 

    Hot rolling and direct cooling

    , Article Comprehensive Materials Processing ; Vol. 3 , 2014 , pp. 377-396 ; ISBN: 9780080965338 Serajzadeh, S ; Sharif University of Technology
    Knowledge of process parameters during and after hot rolling is a significant requirement in order to produce a material with the desired microstructures and mechanical properties. In continuous hot rolling mills, different stages may exist, including water descaling, rolling stands, interstand sections, and run-out table. In each of these sections, various thermal and/or mechanical conditions are applied on the rolling metal that would affect material response in successive stages. In other words, an integrated model should be employed in hot rolling operations to evaluate metal behavior and microstructural events at the same time. Therefore, the thermal-mechanical response as well as... 

    Stress analysis of thermal barrier coating system subjected to out-of-phase thermo-mechanical loadings considering roughness and porosity effect

    , Article Surface and Coatings Technology ; Volume 262 , January , 2015 , Pages 77-86 ; 02578972 (ISSN) Rezvani Rad, M ; Farrahi, G. H ; Azadi, M ; Ghodrati, M ; Sharif University of Technology
    Elsevier  2015
    This paper presents the out-of-phase thermo-mechanical stress analysis of thermal barrier coating (TBC) system in real working conditions used as thermal barrier in diesel engine cylinder heads. The coating system in this research comprises 350. μm zirconium oxide top coat (TC) and 150. μm metallic bond coat (BC). These layers were deposited on the substrate, aluminum A356 alloy, by the aid of air plasma spray (APS) method. Afterwards, the specimen was subjected to thermo-mechanical fatigue (TMF) loadings. Based on the experimental conditions, FE simulations were performed by both time-independent and time-dependent substrate material properties in ABAQUS software. Simulation results related... 

    Thermo-mechanical stress analysis of thermal barrier coating system considering thickness and roughness effects

    , Article Surface and Coatings Technology ; Vol. 243 , 2014 , pp. 91-99 ; ISSN: 02578972 Moridi, A ; Azadi, M ; Farrahi, G. H ; Sharif University of Technology
    Cast aluminium-silicon alloy, A356.0, is widely used in automotive and aerospace industries because of its outstanding mechanical, physical, and casting properties. Thermal barrier coatings can be applied to combustion chamber to reduce fuel consumption and pollutions and also improve fatigue life of components. The purpose of the present work is to simulate stress distribution of A356.0 under thermo-mechanical cyclic loadings, using a two-layer elastic-visco-plastic model of ABAQUS. The results of stress-strain hysteresis loop are validated by an out of phase thermo-mechanical fatigue test. Different thicknesses from 300 to 800. μm of top coat and also roughness of the interfaces are... 

    Numerical simulations of cyclic behaviors in light alloys under isothermal and thermo-mechanical fatigue loadings

    , Article Materials and Design ; Vol. 56 , April , 2014 , pp. 245-253 ; ISSN: 02641275 Farrahi, G. H ; Shamloo, A ; Felfeli, M ; Azadi, M ; Sharif University of Technology
    In this article, numerical simulations of cyclic behaviors in light alloys are conducted under isothermal and thermo-mechanical fatigue loadings. For this purpose, an aluminum alloy (A356) which is widely used in cylinder heads and a magnesium alloy (AZ91) which can be applicable in cylinder heads are considered to study their stress-strain hysteresis loops. Two plasticity approaches including the Chaboche's hardening model and the Nagode's spring-slider model are applied to simulate cyclic behaviors. To validate obtained results, strain-controlled fatigue tests are performed under low cycle and thermo-mechanical fatigue loadings. Numerical results demonstrate a good agreement with... 

    Experimental fatigue lifetime of coated and uncoated aluminum alloy under isothermal and thermo-mechanical loadings

    , Article Ceramics International ; Volume 39, Issue 8 , December , 2013 , Pages 9099-9107 ; 02728842 (ISSN) Azadi, M ; Farrahi, G. H ; Winter, G ; Eichlseder, W ; Sharif University of Technology
    This paper presents the fatigue lifetime of an aluminum-silicon-magnesium alloy, widely used in diesel engine cylinder heads, both with and without a thermal barrier coating (TBC) system. The coating system in this study consists of two layers including a 150 μm thick metallic bond coat and a zirconium oxide top coat 350 μm thick. These coating layers were applied on the substrate of A356.0 alloy by air plasma thermal spraying. The isothermal fatigue tests were conducted in low cycle fatigue (LCF) regime at various temperatures. Out-of-phase thermo-mechanical fatigue (OP-TMF) tests were also performed at different maximum temperatures and constraint factors. Experimental results demonstrate... 

    Effects of strain rate and mean strain on cyclic behavior of aluminum alloys under isothermal and thermo-mechanical fatigue loadings

    , Article International Journal of Fatigue ; Volume 47 , 2013 , Pages 148-153 ; 01421123 (ISSN) Azadi, M ; Sharif University of Technology
    In this paper, effects of strain rate and mean strain on the cyclic behavior and the lifetime of aluminum-silicon alloys are investigated under thermo-mechanical and isothermal fatigue loadings. To achieve these goals, low cycle fatigue tests are accomplished at evaluated temperatures under various strain rates (by changing the loading frequency) and different strain ratios (minimum to maximum strain). Thermo-mechanical fatigue experiments are performed in an out-of-phase condition where the temperature varies between 50 and 250 °C. Various heating/cooling rates are taken into account to assess the strain rate effect and different starting temperatures are considered to study the mean strain... 

    Heat treatment effect on thermo-mechanical fatigue and low cycle fatigue behaviors of A356.0 aluminum alloy

    , Article Materials and Design ; Volume 45 , 2013 , Pages 279-285 ; 02613069 (ISSN) Azadi, M ; Shirazabad, M. M ; Sharif University of Technology
    In the present paper, the heat treatment effect on A356.0, a cast aluminum alloy which has been widely used in diesel engine cylinder heads, is investigated under out-of-phase thermo-mechanical fatigue and low cycle fatigue (at different temperatures) loadings. A typical heat treatment is applied to the material including 8. h solution at 535 °C, water quench and 3. h ageing at 180 °C. The experimental fatigue results show that the heat treatment process has considerable influence on mechanical and low cycle fatigue behaviors, especially at room temperature, but its effect on thermo-mechanical fatigue lifetime is not significant. The improvement in the strength can be explained by the... 

    An integrated model for prediction of thermo-mechanical behaviour of metal and work-rolls during hot strip rolling process

    , Article Proceedings of the Institution of Mechanical Engineers, Part B: Journal of Engineering Manufacture ; Volume 223, Issue 4 , 2009 , Pages 395-407 ; 09544054 (ISSN) Rezaei Farkoosh, A ; Serajzadeh, S ; Sharif University of Technology
    In this paper an integrated model has been developed that is capable of considering the effects of process parameters on the thermo-mechanical behaviour of the work-roll and the strip during hot rolling operations. The commercially finite element package ABAQUS is utilized to solve the governing equations, while an elasto-viscoplastic material behaviour is utilized in the model. The model may be employed in single-pass as well as multi-pass rolling layouts. Various aspects of the hot rolling process are predicted including temperature field and thermo-mechanical stresses within the work-roll as well as temperature, strain, and residual stresses distributions within the strip. To assess the... 

    Modeling the Thermomechanical Behaviour of Shape Memory Materials Using Analytical and Numerical Methods

    , M.Sc. Thesis Sharif University of Technology Taghikhani, Yaser (Author) ; Karimi Taheri, Ali (Supervisor)
    Shape memory materials are a kind of smart materials which recently have been used in a wide range of fields in particular medicine and aerospace. These materials can be divided to shape memory polymers and shape memory alloys. The basis of shape memory alloys’ properties is a thermoelastic martensitic transformation taking place between a high symmetric phase, called Austenite, and a low symmetric phase, called Martensite. In this project, by means of finite element methods, continuum thermomechanics and selection of appropriate internal variables (such as amount and orientation of volumetric fraction of each phase) and control variables (like strain, stress, temperature and entropy), their... 

    Mixed mode fracture analysis of adiabatic cracks in homogeneous and non-homogeneous materials in the framework of partition of unity and the path-independent interaction integral

    , Article Engineering Fracture Mechanics ; Vol. 131, issue , 2014 , Pp. 100-127 ; ISSN: 00137944 Goli, E ; Bayesteh, H ; Mohammadi, S ; Sharif University of Technology
    In this paper, the path independent interaction integral has been implemented in the framework of the extended finite element method for mixed mode adiabatic cracks under thermo-mechanical loadings particularly in orthotropic non-homogenous materials. The mesh insensitivity and increased accuracy due to the thermal and displacement asymptotic analytical solutions are discussed and the contour independency of the interaction integral is investigated in different examples. Finally, the problem of crack propagation in orthotropic FGM materials under the thermal loading is investigated to assess the accuracy and robustness of proposed approach  

    Thermo-mechanical modeling of high speed spindles

    , Article Scientia Iranica ; Volume 19, Issue 2 , 2012 , Pages 282-293 ; 10263098 (ISSN) Zahedi, A ; Movahhedy, M. R ; Sharif University of Technology
    Prediction of the thermo-mechanical behavior of machine-tool spindles is essential in the reliable operation of high speed machine tools. In particular, the performance of these high speed spindles is dependent on their thermal behavior. The main source of heat generation in the spindle is the friction torque in angular contact ball bearings. This paper presents an effort to develop a comprehensive model of high speed spindles that includes viable models for the mechanical and thermal behavior of its major components, i.e., bearings, shaft and housing. Spindle housing and shaft are treated as six-degree-of-freedom Timoshenko beam elements. Bearings are modeled as two-node elements with five... 

    Thermo-mechanical behavior of functionally graded circular sector plates

    , Article Acta Mechanica ; Volume 226, Issue 1 , January , 2015 , Pages 37-54 ; 00015970 (ISSN) Fallah, F ; Nosier, A ; Sharif University of Technology
    Springer-Verlag Wien  2015
    By reformulating the governing equations of the first-order theory into those describing the interior and edge-zone problems of the plate, closed-form solutions are presented for analysis of functionally graded circular sector plates with vertex angle (Formula presented.) whose radial edges are simply supported and subjected to transverse loading and heat conduction through the plate thickness. Various types of clamped, simply supported, and free-edge boundary supports are considered on the circular edge of the plate. The material properties are graded through the plate thickness according to a power-law distribution of the volume fraction of the constituents. The effects of material... 

    The impact of ZrSiO4 nanoparticles addition on the microstructure and properties of dolomite based refractories

    , Article Ceramics International ; Volume 43, Issue 16 , 2017 , Pages 13932-13937 ; 02728842 (ISSN) Ghasemi Kahrizsangi, S ; Karamian, E ; Gheisari Dehsheikh, H ; Sharif University of Technology
    Dolomite base refractories have advantages such as high refractoriness, potential to produce pure steel molten, high alkaline corrosion resistance, and economical for consumers. However, application of these refractories has been limited due to their high potential to hydration with atmosphere humidity. In this research work, the impact of ZrSiO4 nanoparticles addition on the physical, thermo-mechanical, mechanical, and microstructure of the dolomite base refractories is investigated. Also, XRD and SEM/EDX analyses were used for determining generated ceramic phases and microstructure evaluation, respectively. Up to 3 wt% ZrSiO4 nanoparticles were added to the compositions. Compositions fired...