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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...
Structural similitude in free vibration of orthogonally stiffened cylindrical shells
, Article Thin-Walled Structures ; Volume 47, Issue 11 , 2009 , Pages 1316-1330 ; 02638231 (ISSN) ; Navazi, H. M ; Jafari, A. A ; Bagheri, M ; Sharif University of Technology
2009
Abstract
In this paper, the necessary similarity conditions, or scaling laws, for free vibrations of orthogonally stiffened cylindrical shells are developed using the similitude theory. The Donnell-type nonlinear strain-displacement relations along with the smearing theory are used to model the structure. Then the principle of virtual work is used to analyze the free vibration of the stiffened shell. After non-dimensionalizing the derived formulations, the scaling laws are developed, using the similitude theory. Then, different examples are solved to validate the scaling laws numerically and experimentally. The obtained results show the effectiveness of the derived formulations. © 2009 Elsevier Ltd....
Scaled down models for free vibration analysis of orthogonally stiffened cylindrical shells using similitude theory
, Article 26th Congress of International Council of the Aeronautical Sciences 2008, ICAS 2008, Anchorage, AK, 14 September 2008 through 19 September 2008 ; Volume 2 , 2008 , Pages 3458-3469 ; 9781605607153 (ISBN) ; Jafari, A. A ; Navazi, H. M ; Sharif University of Technology
2008
Abstract
In this paper, the necessary similarity conditions, or scaling laws, for free vibrations of orthogonally stiffened cylindrical shells are developed using similitude theory. The Donnelltype nonlinear strain-displacement relations along with smearing theory are used to model the structure. Then the principle of virtual work is used to analyze the free vibration of the stiffened shell. After nondimensionalizing the derived formulations, the scaling laws are developed, using similitude theory. Then, different examples are solved to validate the scaling laws numerically and experimentally. The obtained results show the effectiveness of the derived formulations
Multidisciplinary optimization of a stiffened shell by genetic algorithm
, Article Journal of Mechanical Science and Technology ; Volume 26, Issue 2 , February , 2012 , Pages 517-530 ; 1738494X (ISSN) ; Jafari, A. A ; Azadi, M ; Sharif University of Technology
2012
Abstract
Vibration analysis of simply supported rotating cross-ply laminated stiffened cylindrical shell is performed using an energy approach which includes variational and averaging method. The stiffeners include rings and stringers. The equations are obtained by Rayleigh-Ritz method and Sander's relations. To validate the present method, the results are compared to the results available in other literatures. A good adoption is observed in different type of results including isotropic shells, rotating laminated shells, stiffened isotropic shells and stiffened laminated shells. Then, the optimization of parameters due to shell and stiffeners is conducted by genetic algorithm (GA) method under weight...