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    Effects of nanoparticles on the improvement of the dynamic response of nonuniform-thickness laminated composite beams

    , Article Journal of Mechanical Science and Technology ; Volume 30, Issue 1 , 2016 , Pages 121-125 ; 1738494X (ISSN) Zabihollah, A ; Momeni, S ; Selk Ghafari, A ; Sharif University of Technology
    Korean Society of Mechanical Engineers  2016
    The dynamic behavior of nonuniform-thickness laminated composite beams, such as helicopter blades, wind turbine blades, and robot arms, is of high importance in the design and fabrication of such elements. Changing the thickness of laminated structures is a significant challenge during fabrication because different tapering configurations may significantly alter the stiffness of the structures and thus the dynamic response of the structures. In this study, the effect of adding nanoparticles to resin on the stiffness and dynamic behavior of nonuniform-thickness laminated composite beam elements was investigated. A set of experiments were conducted to examine the natural frequencies and... 

    The second strain gradient theory-based Timoshenko beam model

    , Article JVC/Journal of Vibration and Control ; Volume 23, Issue 13 , 2017 , Pages 2155-2166 ; 10775463 (ISSN) Asghari, M ; Momeni, S. A ; Vatankhah, R ; Sharif University of Technology
    SAGE Publications Inc  2017
    The governing equations of motion, together with the associated boundary conditions, are derived for the second strain gradient Timoshenko micro- and nano-beams. The second strain gradient theory is a highly powerful nonclassical continuum theory, capable of capturing the size effects in micro- and nano-scale structures. In case studies, the static and free-vibration behaviors of a hinged-hinged beam are investigated utilizing the presented second strain gradient theory-based Timoshenko beam model. The obtained results are compared with those of the available models in the literature, which are based on the (first) strain gradient theory, the modified couple stress theory, and the classical... 

    Analysis of an endlessly single-mode penrose-tiling photonic quasicrystal fiber

    , Article Mediterranean Photonics Conference, MePhoCo (3rd :2014:Trani ) ; May , 2014 , 1 - 3 Bahrampour, A ; Iadicicco, A ; Foomezhi, E ; Momeni, S ; Bhrampour, A. R ; Sharif University of Technology
    We propose a 10-fold photonic quasicrystal(QC)pattern as the cladding of modified index guiding quasi crystal fiber. We have studied the single-mode operation regime of the fiber by analyzing the effective V parameter. In this case it is presented an endlessly single mode regime due to V-parameter, and the result is in agreement with finite element method (FEM) simulation result. We present birefringence and electromagnetic field profiles using finite element method  

    Synthesis and application of mesoporous carbon nanospheres containing walnut extract for fabrication of active protective epoxy coatings

    , Article Progress in Organic Coatings ; Volume 133 , 2019 , Pages 206-219 ; 03009440 (ISSN) Haddadi, S. A ; Behroozi Kohlan, T ; Momeni, S ; Ramazani S. A., A ; Mahdavian, M ; Sharif University of Technology
    Elsevier B.V  2019
    In this article, the synthesis procedure of mesoporous carbon nanospheres (MCNSs) using silica hard-templates, doping of the nanospheres with walnut extract, and their impact on active protective properties of an epoxy coating are presented. Field emission scanning electron microscope (FE-SEM) results showed that the synthesis of these nanocontainers was successfully done in spherical form. Thermogravimetric analysis (TGA) and Fourier transform infrared spectroscopy (FT-IR) results showed that walnut extract as a green inhibitor was doped into the pores of nanocapsules. Corrosion resistance of the mild steel samples in the 3.5 wt.% NaCl solution in the presence and absence of walnut extract...