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    On the rolling contact problem of two elastic solids with graded coatings

    , Article International Journal of Mechanical Sciences ; Volume 64, Issue 1 , 2012 , Pages 62-81 ; 00207403 (ISSN) Guler, M. A ; Alinia, Y ; Adibnazari, S ; Sharif University of Technology
    2012
    Abstract
    In this study, the rolling contact problem of two elastically similar cylinders coated with functionally graded materials is investigated. The singular integral equations approach is utilized to extract the governing equations of the problem. The governing equations are discretized into systems of algebraic equations by virtue of the Gauss-Chebyshev integration method. Comprehensive parametric study is performed to examine the effects of mechanical properties, coating thickness and external loads on the surface stress components, stick/slip transition, creep ratio and power loss. This study aimed to emphasize the capability of graded materials in improving the rolling contact fatigue of... 

    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... 

    Harvesting Energy from Magnetic Shape Memory Alloys in Plannar Loading

    , M.Sc. Thesis Sharif University of Technology Karamian Manesh, Mohammad Javad (Author) ; Sayyadi, Hassan (Supervisor)
    Abstract
    Harvesting energy by magnetic shape memory alloy has many advantages against other various methods which harvested from environmental vibrations and has been considered due to high long longevity, large strain amplitude and good performance in low frequencies. These materials can display up to % recoverable strain in response to the application of a magnetic field or compressive mechanical stress. Microstructure of these materials changes under applying mechanical loading and/or magnetic field which cause magnetic vector rotating in magnetic domain. Change in magnetization of these materials, lead to harvesting energy by considering Faraday's law of induction. The model of this... 

    Transverse Retrofit of Infilled Frames with FRP

    , M.Sc. Thesis Sharif University of Technology Goudarzi, Nabi (Author) ; Moghaddam, Hassan (Supervisor)
    Abstract
    Masonry buildings are wide spread in Iran and some other countries . These buildings are highly vulnerable to seismic excitations if not constructed in accordance with engineering fundamentals . Thus it is necessary to retrofit these structures to flee from humanitarian and economical damages inflicted by earthquakes. One of the critical vulnerabilities of masonry buildings is due to transverse instability of it’s infills . Therefore to study out of plane behavior of these elements , an infilled frame is modeled and analyzed with ABAQUS , the results of which is in good congruence with the experimental one . In this model , stress distribution due to one way arching action in the confined... 

    General variable material property formulation for the solution of autofrettaged thick-walled tubes with constant axial strains

    , Article Journal of Pressure Vessel Technology, Transactions of the ASME ; Volume 130, Issue 4 , 2008 , Pages 0412091-0412097 ; 00949930 (ISSN) Farrahi, G. H ; Hosseinian, E ; Assempour, A ; Sharif University of Technology
    2008
    Abstract
    In this paper a general variable material property (VMP) formulation for the solution of thick-walled tubes with constant axial strains was developed and compared with the alternative VMP method that is called the Hencky program The VMP method was initially developed for the analysis of plane stress and plane strain states. However, the actual autofrettage process is under constant axial strain, i.e., open-end and closed-end conditions. Results indicate very good agreement with the Hencky program. Our method is simple, accurate, and very efficient, so that the number of iterations for convergence reduces approximately to one-tenth of Hencky program iterations. The solution algorithm for... 

    A Nonlinear Layerwise Shell Finite Element for Delamination Analysis of Laminated Composite Structures under Large Deformation

    , Ph.D. Dissertation Sharif University of Technology Soltani, Zahra (Author) ; Hosseini Kordkheili, Ali (Supervisor)
    Abstract
    This thesis aims to develop a numerically efficient nonlinear layer-wise shell element formulation for delamination analysis of laminated composite shell structures. The element, in a mesoscale scheme, is formulated based on a zig-zag theory and features three translational degrees of freedom for each node on the mid-surface of the shell in addition with two rotational degrees of freedom for each layer. In this way, the displacement field is formulated via adapting the Mindlin-Reissner theory in each layer and an ordered second-order algorithm for finite rotations. To verify the proposed formulation, many popular benchmark problems for geometric nonlinear analysis of shell problems are... 

    Seismic Performance of Partitions in RC Buildings

    , Ph.D. Dissertation Sharif University of Technology Kazerounian, Alireza (Author) ; Kazemi, Mohammad Taghi (Supervisor)
    Abstract
    Many reinforced concrete frame buildings with masonry partitions have been built all around the world. Observations from past earthquakes show that the partitions can endanger the life of buildings occupants and lead to significant damage and loss. Failure of the partitions can be caused by dynamic vibrations and in-plane and out-of-plane loads/displacements. The interaction between in-plane and out-of-plan behaviors and location of partitions, nonlinearity and higher modes of the structures could affect the out-of- plane seismic demands on partitions. Therefore, there is a need for a comprehensive assessment in order to limit the loss in buildings with masonry partitions. This research... 

    A bending theory for beams with vertical edge crack

    , Article International Journal of Mechanical Sciences ; Volume 52, Issue 7 , July , 2010 , Pages 904-913 ; 00207403 (ISSN) Ebrahimi, A ; Behzad, M ; Meghdari, A ; Sharif University of Technology
    2010
    Abstract
    In this paper a linear continuous theory for bending analysis of beams with an edge crack perpendicular to the neutral plane subject to bending has been developed. The model assumes that the displacement field is a superposition of the classical EulerBernoulli beam's displacement and of a displacement due to the crack. It is assumed that in bending the additional displacement due to crack decreases exponentially with distance from the crack tip. The strain and stress fields have been calculated using this displacement field and the bending equation has been obtained using equilibrium equations. Using a fracture mechanics approach the exponential decay rate has been calculated. There is a... 

    A three-dimensional elasticity solution for functionally graded rotating disks

    , Article Composite Structures ; Volume 92, Issue 5 , 2010 , Pages 1092-1099 ; 02638223 (ISSN) Asghari, M ; Ghafoori, E ; Sharif University of Technology
    2010
    Abstract
    A semi-analytical three-dimensional elasticity solution for rotating functionally graded disks for both of hollow and solid disks is presented. The aim is to generalize an available two-dimensional plane-stress solution to a three-dimensional one. Although for the thin disks problems the two-dimensional solution provides appropriate results, for the thick disks, a three-dimensional elasticity solution should be considered to avoid poor results. It is shown that although the plane-stress solution satisfies all the governing three-dimensional equations of motion and boundary conditions, it fails to give a compatible three-dimensional strain field. A valid three-dimensional solution has been... 

    A continuous vibration theory for beams with a vertical edge crack

    , Article Scientia Iranica ; Volume 17, Issue 3 B , 2010 , Pages 194-204 ; 10263098 (ISSN) Behzad, M ; Ebrahimi, A ; Meghdari, A ; Sharif University of Technology
    2010
    Abstract
    In this paper, a continuous model for flexural vibration of beams with an edge crack perpendicular to the neutral plane has been developed. The model assumes that the displacement field is a superposition of the classical Euler-Bernoulli beam's displacement and of a displacement due to the crack. The additional displacement is assumed to be a product between a function of time and an exponential function of space. The unknown functions and parameters are determined based on the zero stress conditions at the crack faces and the concept of J-integral from fracture mechanics. The governing equation of motion for the beam has been obtained using the Hamilton principle and solved using a modified...