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Showing 2 results for Ovesy
Hamed Mahmoud Soltani, Mahsa Kharazi, Hamid Reza Ovesy,
Volume 18, Issue 5 (9-2018)
Abstract
In this study, the buckling and postbuckling behavior of composite laminates with piezoelectric layers subjected to compressive in-plane loading have been investigated. The effects of coupled electro-mechanical field on the postbuckling and bifurcation point in cross-ply and general lay-up sequences have been studied using layerwise theory (LWT). The LWT used in this study for analyzing the piezo-composite laminate is based on the assumptions of the first order shear deformation theory (FSDT). In order to obtain the equilibrium equations, the principle of minimum potential energy has been employed. The obtained nonlinear equilibrium equations have been solved using Newton-Raphson iterative algorithm. Furthermore, the three dimensional finite element analysis has been performed to examine the accuracy of the results obtained using the proposed method. The obtained analytical results are in good agreement with those achieved through the finite element analysis. Obtained results showed that, location of the piezoelectric layers have significant effect on the buckling and postbuckling behavior of the composite plates. Moreover, number of degrees of freedom which is used in proposed method are less than finite element method which, decreased the computational time cost.
P. Zarifian, H.r. Ovesy, R. Dehghani Firouzabadi,
Volume 19, Issue 6 (June 2019)
Abstract
In the current paper, the flutter of a circular cylindrical shell containing an internal fluid while subjected to supersonic external flow has been investigated. It is noted that the internal fluid is formulated through a simple and novel model, in which the fluid is only represented by the free surface as well as the surrounding structural degrees of freedoms. To this end, a computational Fluid-structure interaction (FSI) model within the framework of the finite element method is developed. The internal liquid is represented by a more sophisticated model, referred to as and the shell structure is modeled by Sanders’ shell theory. The aerodynamic pressure loading is approximated by the first-order piston theory. The initial geometric stiffness due to pre-stresses in the initial configuration stemming from the fluid hydrostatic pressure, internal pressure, and axial compression load is also considered. The validity of the derived formulation is established, using some verification examples. The obtained results reveal as the filling ratio is increased from 0 to 1, the flutter speed increases first as the filling ratio is increased and reaches the maximum value the 0.5 filling ratio; then, it decreases when the filling ratio is further increased and reaches the critical value of an empty shell the 1.0 filling ratio.
