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    Effects of concurrent earthquake and temperature loadings on cable-stayed bridges

    , Article International Journal of Structural Stability and Dynamics ; Volume 16, Issue 6 , 2016 ; 02194554 (ISSN) Maleki, S ; Maghsoudi Barmi, A ; Sharif University of Technology
    World Scientific Publishing Co. Pte Ltd 
    Abstract
    This paper discusses the necessity of considering the concurrent effects of uniform temperature and earthquake loadings in the design of cable-stayed bridges. This load combination is not foreseen in current design standards such as AASHTO and Eurocode. Three-dimensional finite element models of cable-stayed bridges are employed for nonlinear time history analyses. A load combination is proposed that adds uniform temperature loading to the existing extreme event load combination. The proposed combination is compared with existing extreme event load combination and the changes in forces and displacements are noted. A parametric study is then conducted by varying a number of properties of the... 

    Numerical study of the effects of process parameters on tool life in a cold radial forging process

    , Article Scientia Iranica ; Vol. 21, issue. 2 , 2014 , p. 339-346 Afrasiab, H ; Movahhedy, M. R ; Sharif University of Technology
    Abstract
    Radial forging is an open die forging process used for reducing the diameters of shafts, tubes, stepped shafts and axles, and for creating internal profiles in tubes. Due to very large forging loads, the tool should withstand high stress and wear. Therefore, the success of the forging process depends upon recognition of the die failure factors and optimization of the tool working conditions that enhance tool life. In this study, the effect of process parameters on tool life in the cold radial forging process is investigated using nonlinear three dimensional finite element modeling. Wear and mechanical fatigue are considered as the main modes of tool failure, and a parametric study on the... 

    Material tailoring of the femoral component in a total knee replacement to reduce the problem of aseptic loosening

    , Article Materials and Design ; Volume 52 , 2013 , Pages 441-451 ; 02641275 (ISSN) Bahraminasab, M ; Sahari, B. B ; Edwards, K. L ; Farahmand, F ; Hong, T. S ; Naghibi, H ; Sharif University of Technology
    Elsevier Ltd  2013
    Abstract
    Aseptic loosening of femoral components is a significant problem affecting the life of current total knee replacements. To help reduce the problem of aseptic loosening, a new metal-ceramic poros functionally graded biomaterial (FGBM) has been designed to replace the existing metal alloy material normally used. In order to investigate the effect of using a FGBM on distal femur stresses compared to using standard material in a femoral component, a three-dimensional finite element model of the knee prosthesis has been developed. The results of the modeling and subsequent analysis indicate that by using the new FGBM compared to the existing material in a femoral component, higher levels of... 

    Proposal of a new design for valveless micropumps

    , Article Scientia Iranica ; Volume 18, Issue 6 , December , 2011 , Pages 1261-1266 ; 10263098 (ISSN) Afrasiab, H ; Movahhedy, M. R ; Assempour, A ; Sharif University of Technology
    2011
    Abstract
    A new design for a valveless micropumping device has been proposed that integrates two existing pumping technologies, namely, the wall induced traveling wave and the obstacle-type valveless micropump. The liquid in the microchannel is transported by generating a traveling wave on the channel, while the placing of two asymmetric trapezoid obstacles, along the centerline of the channel inlet and outlet, leads to a significant (up to seven times) increase of the net flow rate of the device. The effectiveness of this innovative design has been proved through a verified three-dimensional finite element model. FluidStructure Interaction (FSI) analysis is performed in the framework of an Arbitrary... 

    A combined experimental and numerical study of the effect of surface roughness on nanoindentation

    , Article International Journal of Applied Mechanics ; Volume 11, Issue 7 , 2019 ; 17588251 (ISSN) Nazemian, M ; Chamani, M ; Baghani, M ; Sharif University of Technology
    World Scientific Publishing Co. Pte Ltd  2019
    Abstract
    Gold and copper thin films are widely used in microelectromechanical system (MEMS) and nanoelectromechanical system (NEMS) devices. Nanoindentation has been developed in mechanical characterization of thin films in recent years. Several researchers have examined the effect of surface roughness on nanoindentation results. It is proved that the surface roughness has great importance in nanoindentation of thin films. In this paper, the surface topography of thin films is simulated using the extracted data from the atomic force microscopy (AFM) images. Nanoindentation on a rough surface is simulated using a three-dimensional finite-element model. The results are compared with the results of... 

    Friction-stir lap-joining of aluminium-magnesium/poly-methyl-methacrylate hybrid structures: thermo-mechanical modelling and experimental feasibility study

    , Article Science and Technology of Welding and Joining ; Volume 23, Issue 1 , 2018 , Pages 35-49 ; 13621718 (ISSN) Aghajani Derazkola, H ; Khodabakhshi, F ; Simchi, A ; Sharif University of Technology
    Taylor and Francis Ltd  2018
    Abstract
    In this research, the feasibility of friction-stir welding (FSW) for dissimilar lap-joining of an aluminium-magnesium alloy (AA5058) and poly-methyl-methacrylate sheets to attain sound and defect-free joints was examined. The inter-mixing flow patterns between the metal and polymer counterparts during FSW were predicted by employing three-dimensional finite element models. It is shown that the bonding mechanism between the dissimilar materials is mechanical interlocking at the interface which controls the joint strength depending on the processing parameters. The most suitable dissimilar lap-joining regarding microstructural soundness is attained at w= 1600 rev min−1 and v = 25 mm min−1.... 

    Experimental and analytical model analysis of Babolsar's steel arch bridge

    , Article 3rd International Conference on Bridge Maintenance, Safety and Management - Bridge Maintenance, Safety, Management, Life-Cycle Performance and Cost, Porto, 16 July 2006 through 19 July 2006 ; 2006 , Pages 235-237 ; 0415403154 (ISBN); 9780415403153 (ISBN) Beygi, M. H. A ; Kazemi, M. T ; Lark, B ; Tabrizian, Z ; Sharif University of Technology
    Taylor and Francis/ Balkema  2006
    Abstract
    The paper presents the experimental and analytical model analysis of a steel-girder arch bridge. The field test is carried out by ambient vibration testing under traffic excitations. Both the peak picking method in the frequency domain and the stochastic subspace identification method in the time domain are used for the output-only model identification. A good agreement in identified frequencies has been found between the two methods. It is further demonstrated that the stochastic subspace method provides better mode shapes. The three-dimensional finite element models are constructed and an analytical model analysis is then performed to generate natural frequencies and mode shapes in the...