Search for: axial-buckling
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    Grooves effect on crashworthiness characteristics of thin-walled tubes under axial compression

    , Article Materials and Design ; Volume 23, Issue 7 , 2002 , Pages 611-617 ; 02641275 (ISSN) Daneshi, G. H ; Hosseinipour, S. J ; Sharif University of Technology
    Crashworthiness characteristics of thin-walled steel tubes containing annular grooves are experimentally studied. The grooves are introduced in the tube to force the plastic deformation to occur at predetermined intervals along the tube. The aims are improving the uniformity of the load-displacement behaviour and predicting energy absorption capacity of the tubes. Quasi-static axial crushing tests are performed with different groove distances. Load-displacement curves are described and energy absorption and mean post-buckling load are determined. The results show that the load-displacement curve and energy absorbed by the axial crushing of tubes could be controlled by the introduction of... 

    Free Vibration and Buckling Analysis of a Laminated Composite Cylinder Made of Functionally Graded Material with Lengthwise Properties Variation Including Thermal Effects

    , M.Sc. Thesis Sharif University of Technology Hashemi, Mehdi (Author) ; Kargarnovin, Mohammad Hossein (Supervisor)
    In recent decades, employing fiber-reinforced composite has growing field in various industries due to distinct features like high specific stiffness and strength. Studies in case of this type of composite have not been stopped and nowadays, widespread researches are conducted over optimization of them. As a result, the effect of distributing fiber in this composite by taking the concept of functionally graded materials, on vibrations and buckling behaviors including natural frequencies and minimum axial bulking load under different boundary conditions for a multi-layered cylindrical shell in which volume fraction of fiber along its length varies according to power-law model are investigated... 

    Stability analysis of carbon nanotubes using a hybrid atomistic-structural element

    , Article International Journal of Nanomanufacturing ; Volume 5, Issue 3-4 , 2010 , Pages 366-375 ; 17469392 (ISSN) Sadeghi, M ; Naghdabadi, R ; Sharif University of Technology
    In this paper, a hybrid atomistic-structural element for studying the mechanical behaviour of carbon nanotubes is introduced. Non-linear formulation for this element is derived based on empirical inter-atomic potentials. This hybrid element is capable of taking into account the non-linear nature of inter-atomic forces as well as the non-linearity arising from large deformations. Using these capabilities, the stability analysis of carbon nanotubes under axial compressive loading is performed and the post-buckling behaviour is predicted. Also, the dependence of axial buckling force on nanotube radius is shown  

    Buckling analysis of multilayered functionally graded composite cylindrical shells

    , Article Applied Mechanics and Materials ; Volume 108 , 2012 , Pages 74-79 ; 16609336 (ISSN) ; 9783037852729 (ISBN) Kargarnovin, M. H ; Hashemi, M ; Sharif University of Technology
    In this paper, the buckling analysis of a multilayered composite cylindrical shell which volume fraction of its fiber varies according to power law in longitudinal direction, due to applied compressive axial load is studied. Rule of mixture model and reverse of that are employed to represent elastic properties of this fiber reinforced functionally graded composite. Strain displacement relations employed are based on Reissner-Naghdi-Berry's shell theory. The displacement finite element model of the equilibrium equations is derived by employing weak form formulation. The Lagrangian shape function for in-plane displacements and Hermitian shape function for displacement in normal direction to... 

    Investigating the effect of carbon nanotube defects on the column and shell buckling of carbon nanotube-polymer composites using multiscale modeling

    , Article International Journal for Multiscale Computational Engineering ; Volume 7, Issue 5 , 2009 , Pages 431-444 ; 15431649 (ISSN) Montazeri, A ; Naghdabadi, R ; Sharif University of Technology
    Carbon nanotube (CNT)-reinforced polymer composites have attracted great attention due to their exceptionally high strength. Their high strength can be affected by the presence of defects in the nanotubes used as reinforcements in practical nanocomposites. In this article, a new three-phase molecular structural mechanics/finite element (MSM/FE) multiscale model is used to study the effect of CNT vacancy defects on the stability of single-wall (SW) CNT-polymer composites. The nanotube is modeled at the atomistic scale using MSM, whereas the interphase layer and polymer matrix are analyzed by the FE method. The nanotube and polymer matrix are assumed to be bonded by van der Waals interactions...