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    Buckling Analysis of Reinforced Composite Conical Shells under Axial Compressive Load using GDQ Method

    , M.Sc. Thesis Sharif University of Technology Gholami, Peyman (Author) ; Kouchakzadeh, Mohammad Ali (Supervisor) ; Shakouri, Meysam ($item.subfieldsMap.e) ; Noghabi, Mohammad ($item.subfieldsMap.e)
    The object of this study is to determine the buckling load of reinforced composite conical shells under axial compression. . Shells are reinforced by stringers and rings and the boundary conditions are assumed to be simply supported. At first the equilibrium equations are obtained using the first order shear deformation theory (FSDT), smeared stiffener technique and principle of minimum potential energy. In the following, the resulting equations which are the system of five variable coefficient partial differential equations in terms of displacement components are investigated by generalized differential quadrature method (GDQM). Finally the standard eigenvalue equation is formed and the... 

    Analytical solution for axisymmetric buckling of joined conical shells under axial compression

    , Article Structural Engineering and Mechanics ; Volume 54, Issue 4 , 2015 , Pages 649-664 ; 12254568 (ISSN) Kouchakzadeh, M. A ; Shakouri, M ; Sharif University of Technology
    Techno Press  2015
    In this study, the authors present an analytical approach to find the axisymmetric buckling load of two joined isotropic conical shells under axial compression. The problem of two joined conical shells may be considered as the generalized form of joined cylindrical and conical shells with constant or stepped thicknesses. Thickness of each cone is constant; however it may be different from the thickness of the other cone. The boundary conditions are assumed to be simply supported with rigid rings. The governing equations for the conical shells are obtained and solved with an analytical approach. A simple closed-form expression is obtained for the buckling load of two joined truncated conical... 

    Buckling Analysis of FG and Multilayered Cylindrical Shells Based on Third-Order Shear Deformation Theory

    , M.Sc. Thesis Sharif University of Technology Azizi, Mohsen (Author) ; Fallah Ragabzadeh, Famida (Supervisor) ; Zohoor, Hassan (Supervisor)
    In this study, based on Donnel’s shell theory and the theory of third-order shear deformation, and taking into consideration von Karman non-linearity terms, the analysis of buckling of functionally graded (FG) and multi-layered cylindrical shell with transversely isotropic layers, subjected to different loadings, was done. Along this line, first using the principle of minimum total potential energy, and based on the Donnel’s shell theory and the theory of third-order shear deformation, five couple equilibrium equations for cylindrical shell were produced. Next these five coupled equilibrium equations were reduced to three uncoupled equilibrium equation which are, in terms of transverse... 

    Buckling and postbuckling of advanced grid stiffened truncated conical shells with laminated composite skins

    , Article Thin-Walled Structures ; Volume 149 , 2020 Bohlooly, M ; Kouchakzadeh, M. A ; Mirzavand, B ; Noghabi, M ; Sharif University of Technology
    Elsevier Ltd  2020
    A theoretical approach is presented to derive an explicit formula for buckling load and postbuckling path of advanced grid stiffened conical shells (stiffeners with laminated composite skins). Different types of fiber paths of grids including stringer, ring, and helical are considered. The simply supported truncated conical shell with imperfection is subjected to axial compression. Basic formulations are constructed using the classical theory of shells and von Karman type of nonlinear strain-displacement relationships. The equilibrium and compatibility equations are solved by Galerkin procedure, and an explicit relation is obtained to predict the equilibrium paths. Results for different... 

    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...