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cylindrical-shell
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Buckling analysis of nonlocal anisotropic thin-walled cylindrical shells subject to combined loading
, Article Journal of Engineering Mechanics ; Volume 142, Issue 12 , 2016 ; 07339399 (ISSN) ; Fazelzadeh, S. A ; Sohrabpour, S ; Sharif University of Technology
American Society of Civil Engineers (ASCE)
2016
Abstract
The equilibrium governing equations of nonlocal anisotropic thin-walled circular cylindrical shell under combined axial compressive force, torsional load, and external pressure are explicitly derived. This is accomplished by appropriately combining the equilibrium equations and the strain-displacement relations according to Flügge's shell theory and the stress-stain equations of Eringen's nonlocal elasticity theory. An analytical solution for the buckling of the shells is presented by using the complex method. This model is validated by a good agreement between the results given by the present model and available data in the literature. Furthermore, the model is utilized to elucidate the...
Free Vibration Analysis of Thin Truncated Cylindrical Shells using Galerkin Approach
, M.Sc. Thesis Sharif University of Technology ; Dehghani Firouzabadi, Rohollah (Supervisor)
Abstract
The current study is dedicated to free vibration analysis of a thin cylindrical shell with an oblique end. To this end, governing equations of motion and the corresponding boundary conditions are derived using Hamiltonian formulations. The differential form of equations is obtained by applying by part integration to the integral form of equations of motion. Equations of motions have been solved by Galerkin method for two different kinds of boundary conditions. Convergence process for different kinds of conditions has been done and results compared with papers. The effect of different parameters such as, length of cylinder, oblique angle, thickness etc. on the fundamental frequencies has been...
Sability and Sibration Analysis for a Type of Special Nano Motor Based on Cylindrical Shell Equations and Nonlocal Elastisity Theory
, M.Sc. Thesis Sharif University of Technology ; Dehghani Firouzabadi, Rohollah (Supervisor) ; Haddadpour, Hassan (Co-Advisor)
Abstract
The present study investigates the vibrational behavior of a special type of nano-motor based on a thin cylindrical shell model and the nonlocal elasticity theory of Eringen. The presumed nano-motor is comprised of three single walled carbon nanotubes (CNT), where two of them are cantilevered and the third one is located in the middle. The CNT in the middle will suspend due to the Van-der-Waals forces generated from the interaction by the cantilevered CNT pair. Some proper chirality arrangements can conduct electricity and make the middle CNT rotate in extremely high speeds. In fact, the middle CNT rotates on a frictionless elastic foundation. In the present study, the nano-motor is modeled...
Dynamic Analysis of Rotating Stiffened Cylindrical Shell Using Improved Finite Element Method
, M.Sc. Thesis Sharif University of Technology ; Kouchakzadeh, Mohammad Ali (Supervisor)
Abstract
In this research, the dynamic behavior of a rotating stiffened cylindrical shell has been investigated using the refined finite element method. Refined FEM means decreasing degrees of freedom based on decoupling the structure to longitudinal and layerwise directions. The refined FEM has been used to solve the 3D rotor dynamics equations. The natural frequencies and the corresponding modes have been calculated and verified for some existed data and problems. In addition, the effects of the shell geometry dimensions on the natural frequencies and mode shapes have been studied. Also, the relationship between the length to radius ratio, radius to thickness ratio, rotational speed, Aspect ratio...
Nonlinear Vibrations and Stability Analysis of Rotating Cylindrical Shells Conveying Annular Fluid Medium
, Ph.D. Dissertation Sharif University of Technology ; Dehghan Firouzabadi, Rohollah (Supervisor) ; Rahmanian, Mohammad (Co-Supervisor)
Abstract
In this study, stability as well as linear and nonlinear vibrations of coaxial rotating cylindrical shells conveying annular incompressible fluid medium are investigated. To this aim the inner isotropic and elastic rotating cylindrical shell along with the rigid and stationary outer cylinder are considered. Equations of motion for the inner cylinder are determined according to the Hamilton’s principle and using the Sanders-Koiter theory assumptions. In order to generalize the boundary condition implementation, some translational and rotational springs are attached to the boundaries at the mid-plane. The final system of equations are solved by means of the extended Galerkin method – being an...
A parametric study of seismic response in anchored steel tanks with endurance time method
, Article Scientia Iranica ; Vol. 21, Issue. 5 , 2014 , pp. 1608-1619 ; ISSN: 10263098 ; Estekanchi, H. E ; Vafai, A ; Sharif University of Technology
Abstract
In this paper, the seismic response of anchored cylindrical steel tanks with various dimensional parameters has been investigated by endurance time method considering fluid-structure interaction effects. Various response quantities, such as stresses and displacements, have been evaluated by subjecting tanks to specially designed intensifying accelerograms and their performance is judged based on their response at predefined level(s) of dynamic excitation. It is shown that ET analysis can reliably predict the result of ground motion time history analysis in all seven tank models studied. In four of the tanks in which height of the shell and the level of fluid is the same, the variation of...
Accurate calculation of the natural frequencies of reticulated and solid cylindrical composite shells
, Article Applied Mechanics and Materials, 29 July 2011 through 31 July 2011, Bangkok ; Volume 110-116 , July , 2012 , Pages 4598-4606 ; 16609336 (ISSN) ; 9783037852620 (ISBN) ; Kargarnovin, M. H ; Jam, J. E ; Sharif University of Technology
2012
Abstract
There are hundreds models of reticulated structures including the squared reticulated cylindrical shells. It is considered as comprising of a number of circumferential and longitudinal rods. Analytical governing equation for natural frequencies has been derived for this type of structures and to verify the validity of solutions, Finite Element Method (FEM) is used. The comparison of results demonstrate close agreement between analytical and FE solutions. Also a comparison is preformed between a reticulated and equivalent solid hollow cylinder shell. The equivalent solid hollow cylinder has equal weight, length and outer diameter with the squared reticulated cylindrical shell. This comparison...
Aero-thermo-elastic stability analysis of sandwich viscoelastic cylindrical shells in supersonic airflow
, Article Composite Structures ; Volume 147 , 2016 , Pages 185-196 ; 02638223 (ISSN) ; Sadeghmanesh, M ; Haddadpour, H ; Sharif University of Technology
Elsevier Ltd
2016
Abstract
The aero-thermo-elastic stability of layered cylindrical shells with viscoelstic cores is investigated. The Donnell's shell theory for the outer layers and the first order shear deformation theory for the viscoelastic layer are employed in conjunction with the von Karman-Donnell kinematic nonlinearity to construct the model. The pre-stresses and pre-deformations arisen from the temperature rise and static aerodynamic pressure are first determined by solving the nonlinear thermo-elastic equilibrium equations using by an exact analytical method. The results are then used in the linear aeroelastic stability equations and analyzed with the Galerkin's procedure to determine the supersonic flutter...
Elastic-plastic behavior of sandwich cylindrical shell panels with a flexible core
, Article Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science ; Volume 231, Issue 2 , 2017 , Pages 223-241 ; 09544062 (ISSN) ; Fallah, F ; Naghdabadi, R ; Kargarnovin, M. H ; Sharif University of Technology
SAGE Publications Ltd
2017
Abstract
The linear static elastic-plastic behavior of sandwich cylindrical shell panels under a generally distributed loading with thick flexible core is studied. The core modeling is based on high-order theory of sandwich structures in which the in-plane stresses of the core are neglected. The faces are modeled based on Kirchhoff-Love shell theory. The materials of the faces and the core are assumed to be isotropic with linear work hardening behavior. The incremental Prandtl-Reuss plastic flow theory is used in this analysis. Using the principle of virtual displacements, the governing equations are derived and solved for any sort of boundary conditions based on elastic-plastic harmonic differential...
Standard and boundary layer perturbation approaches to predict nonlinear axisymmetric behavior of cylindrical shells
, Article Composite Structures ; Volume 204 , 2018 , Pages 855-881 ; 02638223 (ISSN) ; Taati, E ; Asghari, M ; Reddy, J. N ; Sharif University of Technology
Elsevier Ltd
2018
Abstract
The feasibility and performance of standard and boundary layer perturbation techniques in nonlinear analyses of cylindrical shells are investigated. To this end, the nonlinear axisymmetric behavior of short and long functionally graded (FG) cylindrical shells is considered. The nonlinear governing equations of shell theory with first-order approximation and the von Karman nonlinearity are decoupled. This uncoupling makes it possible to present an analytical solution. A new boundary layer perturbation solution is presented by reducing the governing equations to a normalized form of boundary-layer type. Also, the uncoupled governing equations are solved using standard one-, two-, and...
Free vibration of bi-material cylindrical shells
, Article Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science ; Volume 230, Issue 15 , 2016 , Pages 2637-2649 ; 09544062 (ISSN) ; Foumani, M. S ; Navazi, H. M ; Sharif University of Technology
SAGE Publications Ltd
2016
Abstract
Based on the Sanders thin shell theory, this paper presents an exact solution for the vibration of circular cylindrical shell made of two different materials. The shell is sub-divided into two segments and the state-space technique is employed to derive the homogenous differential equations. Then continuity conditions are applied where the material of the cylindrical shell changes. Shells with various combinations of end boundary conditions are analyzed by the proposed method. Finally, solving different examples, the effect of geometric parameters as well as BCs on the vibration of the bi-material shell is studied
An approach in deformation and stress analysis of elasto-plastic sandwich cylindrical shell panels based on harmonic differential quadrature method
, Article Journal of Sandwich Structures and Materials ; Volume 19, Issue 2 , 2017 , Pages 167-191 ; 10996362 (ISSN) ; Fallah, F ; Kargarnovin, M. H ; Sharif University of Technology
Abstract
Using harmonic differential quadrature method, an approach to analyze sandwich cylindrical shell panels with any sort of boundary conditions under a generally distributed static loading, undergoing elasto-plastic deformation is proposed. The faces of the sandwich shell panel are made of some isotropic materials with linear work hardening behavior while the core is assumed to be an isotropic material experiencing only elastic behavior. The faces are modeled as thin cylindrical shells obeying the Kirchhoff–Love assumptions. For the core material, it is assumed to be thick and the in-plane stresses are negligible. Upon application of an inner and outer general lateral loading, the governing...
Free vibration analysis of rotating laminated cylindrical shells under different boundary conditions using a combination of the layerwise theory and wave propagation approach
, Article Scientia Iranica ; Volume 16, Issue 2 B , 2009 , Pages 168-176 ; 10263098 (ISSN) ; Ahmadian, M. T ; Sharif University of Technology
2009
Abstract
In this paper, vibration analysis of rotating laminated composite cylindrical shells using a combination of the layerwise theory and wave propagation approach is investigated. This combination enables us to study all the conventional boundary conditions in our analysis. Results obtained have been compared with those available in the literature and a good agreement has been observed. In contrast to the Equivalent Single Layer theories (ESL), the layerwise theory is constructed on the basis ofC°- continuity through the laminate thickness. For the surface of the shell, a displacement field based on the wave propagation approach is proposed. The effect of Coriolis and centrifugal accelerations...
Dynamics and stability analysis of rotating cylindrical shells in annular fluid medium
, Article International Journal of Structural Stability and Dynamics ; Volume 20, Issue 8 , 2020 ; Firouz Abadi, R. D ; Rahmanian, M ; Sharif University of Technology
World Scientific
2020
Abstract
Stability and dynamics of rotating coaxial cylindrical shells conveying incompressible and inviscid fluid are investigated. The interior shell is assumed to be flexible while the exterior cylinder is rigid. Using Sander's-Koiter theory assumptions and following Hamilton's principle, governing equations of motion are determined in their integral form. Employing the extended Galerkin method of solution, the integral equations of motion are projected to their equivalent system of algebraic equations. Fluid equations are fundamentally based on the linearized inviscid Navier-Stokes equations. Impermeability condition on the fluid and structure interface as well as the zero radial velocity...
Vibration analysis of size dependent micro FML cylindrical shell reinforced by CNTs based on modified couple stress theory
, Article Arabian Journal of Chemistry ; Volume 15, Issue 10 , 2022 ; 18785352 (ISSN) ; Hooman, M ; Yarigarravesh, M ; Algarni, M ; Jade Catalan Opulencia, M ; Alsaikhan, F ; Turki Jalil, A ; Mohamed, A ; M.AboRas, K ; Lutfor Rahman, M ; Sani Sarjadi, M ; Sharif University of Technology
Elsevier B.V
2022
Abstract
In this manuscript, the sequel of agglomeration on the vibration of fiber metal laminated (FML) cylindrical shell in the micro phase using developed couple stress theory (MCST). Hamilton's principle has been carried out for deriving the non-classical equations of motion of size-dependent thin micro cylindrical shell on the basis of Love's first approximation theory. Mori-Tanaka and extended rule of mixture are utilized to estimate the mechanical attributes of carbon nanotubes (CNTs) and equivalent fiber, respectively. These four phases CNTs/fiber/polymer/metal laminated (CNTFPML) micro cylindrical shell is analyzed applying beam modal function model for several boundary limitations. Then, an...
Nonlinear vibrations and stability of rotating cylindrical shells conveying annular fluid medium
, Article Thin-Walled Structures ; Volume 171 , 2022 ; 02638231 (ISSN) ; Firouz abadi, R. D ; Rahmanian, M ; Sharif University of Technology
Elsevier Ltd
2022
Abstract
This study aims to investigate the nonlinear dynamic characteristics of annular cylinders coupled with a fluid medium to identify the effective parameters on stability margins at different rotation speeds. To achieve this, stability and nonlinear vibrations of rotating cylindrical shells containing incompressible annular fluid are considered. The fluid medium is bounded by a rigid external cylinder. Sanders–Koiter kinematic assumptions are utilized to determine the geometrically nonlinear structural equations of motion. These equations are then used to investigate finite amplitude vibrations of various fluid-loaded shells at different states. A penalty approach is introduced by using...
Free Vibration Analysis of Composite Sandwich Cylindrical Shells with Magneto-Rheological Fluid Core
, M.Sc. Thesis Sharif University of Technology ; Koochakzadeh, Mohammad Ali (Supervisor)
Abstract
Free vibration characteristics analysis of circular sandwich cylindrical shells will be investigated in this research. Sanders thin shell theory will be used for modeling base and constraint layers. Hamilton Principals will be applied to obtain governing equation of motion for the problem. Galerkin-Fourier procedure will be used to solve obtained partial differential equation of the sandwich cylindrical shell. Effects of magnetic field intensity, MR layer, base layer and constraint layer thicknesses, and boundary conditions will be investigated on vibration frequency and modal loss factor of the cylindrical shell. Finally, we will compare the performance of using a viscoelastic and an...
Streaming Algorithms for Shape Fitting in High Dimensions
, M.Sc. Thesis Sharif University of Technology ; Zarrabizadeh, Hamid (Supervisor)
Abstract
In this research, we investigate shape fitting problems in high dimensional streams and we provide lower bounds for the problems of minimum enclosing spherical shell and minimum enclosing cylindrical shell in streaming model. We will prove that no streaming algorithm can approximate these problems with constant factor with storage sub-exponential in dimension. More precisely, we will prove that every streaming algorithm that can solve these problems with storage sub-exponential in dimension, does not have an approximation factor better than√28 d1/3, where d is dimension of the input points. This is the first lower bound that has been proved for these two problems in high dimensional streams
Comparison of natural frequencies of composite cylindrical shells: A squared lattice with its equivalent seamless one
, Article Proceedings of the ASME Design Engineering Technical Conference, 15 August 2010 through 18 August 2010 ; Volume 5 , 2010 , Pages 835-841 ; 9780791844137 (ISBN) ; Jam, J. E ; Hashemian, A. H ; Sharif University of Technology
Abstract
Modern Latticed composite materials whose high specific strength and stiffness are utilized in spacecraft and rocket structures to a sufficiently high extent are now widely used in primary airframe structures. In this work a comparison between squared latticed composite cylinder shells and the equivalent hollow cylinder with same weight, outer radius, length and material is done. An analytical equation is derived for natural frequency of square latticed composite shells. The first fifth modes are taken to be compared. The analytical and FEM results are shown and compared to each other. Also, as discussed, the squared lattice cylinder shell reaches to their natural frequencies easily than the...
Free vibration analysis of functionally graded cylindrical shells including thermal effects
, Article Thin-Walled Structures ; Volume 45, Issue 6 , 2007 , Pages 591-599 ; 02638231 (ISSN) ; Mahmoudkhani, S ; Navazi, H. M ; Sharif University of Technology
2007
Abstract
Free vibration analysis of simply supported FG cylindrical shells for four sets of in-plane boundary conditions is performed. The material properties are assumed to be temperature-dependant and gradually changed in the thickness direction of the shell. The effects of temperature rise are investigated by specifying arbitrary high temperature on the outer surface and the ambient temperature on the inner surface of the cylinder. Distribution of temperature across the shell thickness is found from steady state heat conduction only in the thickness direction. The equations of motion are based on Love's shell theory and the von Karman-Donnell-type of kinematic nonlinearity. The static analysis is...