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    The effects of proportional loading, plane stress, and constant thickness assumptions on hydro-mechanical deep drawing process

    , Article International Journal of Mechanical Sciences ; Volume 53, Issue 5 , 2011 , Pages 329-337 ; 00207403 (ISSN) Taghipour, E ; Assempour, A ; Sharif University of Technology
    Abstract
    The goal of this study is to evaluate the effects of proportional loading, plane stress, and constant thickness assumptions on hydro-mechanical deep drawing (HDD) by developing analytical models. The main model includes no simplifying assumption, and then each of the mentioned assumptions is considered in a specific model. The interrelationships between geometrical and mechanical variables are obtained in the finite difference form based on the incremental strain theory, thereby being solved by Broyden algorithm. Published experimental and FE results are used for evaluation of the results obtained in the present work. The results of models under proportional loading, plane stress, and... 

    Transient growth of a micro-void in an infinite medium under thermal load with modified Zerilli‚ÄďArmstrong model

    , Article Acta Mechanica ; Volume 227, Issue 4 , 2016 , Pages 943-953 ; 00015970 (ISSN) Baghani, M ; Eskandari, A. H ; Zakerzadeh, M. R ; Sharif University of Technology
    Abstract
    In this paper, the transient growth of a spherical micro-void under remote thermal load in an infinite medium is investigated. After developing the governing equations in the problem domain, the coupled nonlinear set of equations is solved through a numerical scheme. It is shown that a small cavity can grow rapidly as the temperature increases in a remote distance and may damage the material containing preexisting micro-voids. Conducting a transient thermal analysis simultaneously with a structural one reveals that the material may experience a peak in the radial stress distribution, which is five times larger compared to the steady-state one, and shows the importance of employing a... 

    Constitutive law of finite deformation elastoplasticity with proportional loadings

    , Article Journal of Pressure Vessel Technology, Transactions of the ASME ; Volume 135, Issue 6 , September , 2013 ; 00949930 (ISSN) Darijani, H ; Naghdabadi, R ; Sharif University of Technology
    2013
    Abstract
    In this paper, decomposition of the total strain into elastic and plastic parts is investigated for extension of elastic-type constitutive models to finite deformation elastoplasticity. In order to model the elastic behavior, a Hookean-type constitutive equation based on the logarithmic strain is considered. Based on this constitutive equation and assuming the deformation theory of Hencky as well as the yield criteria of von Mises, the elastic-plastic behavior of materials at finite deformation is modeled in the case of the proportional loading. Moreover, this elastoplastic model is applied in order to determine the stress distribution in thick-walled cylindrical pressure vessels at finite... 

    A 3-D phenomenological constitutive model for shape memory alloys under multiaxial loadings

    , Article International Journal of Plasticity ; Volume 26, Issue 7 , July , 2010 , Pages 976-991 ; 07496419 (ISSN) Arghavani, J ; Auricchio, F ; Naghdabadi, R ; Reali, A ; Sohrabpour, S ; Sharif University of Technology
    2010
    Abstract
    This paper presents a new phenomenological constitutive model for shape memory alloys, developed within the framework of irreversible thermodynamics and based on a scalar and a tensorial internal variable. In particular, the model uses a measure of the amount of stress-induced martensite as scalar internal variable and the preferred direction of variants as independent tensorial internal variable. Using this approach, it is possible to account for variant reorientation and for the effects of multiaxial non-proportional loadings in a more accurate form than previously done. In particular, we propose a model that has the property of completely decoupling the pure reorientation mechanism from... 

    Experimental accuracy assessment of various high-cycle fatigue criteria for a critical component with a complicated geometry and multi-input random non-proportional 3D stress components

    , Article Engineering Failure Analysis ; Volume 90 , 2018 , Pages 534-553 ; 13506307 (ISSN) Kashyzadeh, K. R ; Farrahi, G. H ; Shariyat, M ; Ahmadian, M. T ; Sharif University of Technology
    Elsevier Ltd  2018
    Abstract
    In the present paper, a steering knuckle of a passenger car that serves as a highly critical component from the safety point of view, is considered to evaluate accuracy some of categories of the multiaxial fatigue criteria, through comparing their predictions with the experimental results. This component is subjected to the highest road- and steering-induced random and non-proportional loads that are exerted on several points of the component. The mechanical properties and fatigue strengths are determined experimentally and the fatigue life assessment tests are performed by the authors. Quantometric analyses and scanning electron microscope (SEM) have been employed to detect the failure...