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Showing 3 results for Assumed Mode Method
Behzad Ghadiri, Mani. Razi, Sabah Hamidi,
Volume 9, Issue 1 (12-2009)
Abstract
In this paper linear aeroelastic analysis of a swept wing with two degrees of freedom in an incompressible flow is investigated in time - domain. The equations of the motion of an elastic wing are derived from Lagrange’s equations in time - domain. The wing is modeled as a cantilever beam rigidly connected to the root. Considering assumed modes of cantilever beam, aerodynamic forces and moments acting on the wing are derived using strip - theory in an unsteady incompressible potential fluid flow. The governing aeroelastic equations of the system have been introduced in dimensionless form. These equations are solved via a numerical method. Comparisons between obtained results and both available experimental data and the results of some cited references indicate a close agreement.
Vahid Rezaei, Ali Mohammad Shafei,
Volume 17, Issue 12 (2-2018)
Abstract
In this article, the dynamic equations of multiple flexible links robotic manipulators fabricated of functionally graded materials (FGM), whose properties vary continuously along the axial direction and also along the thickness, are examined. Gibbs-Appell methodology and Timoshenko Beam Theory according to the Assumed Mode Method are utilized to obtain the equations of motion and to model the flexible characteristics of links, respectively. Subsequently, the influence of power law index on the vibration response of a two-link functionally graded robotic manipulator is studied for two cases in which the mechanical properties of links vary once along the axial direction and again along the thickness direction of each link. By introducing a parameter called signal energy, it is shown that the power law index has a substantial effect on the vibrational behaviors of the mentioned system; and that by choosing a proper power law index, system vibrations can be reduced considerably in a passive way.
S. Koohestani,
Volume 19, Issue 8 (8-2019)
Abstract
In this study, effect of shroud on dynamic characteristics of a rotating multi blade system is investigated. The main aim of this study is to investigate the effect of shroud stiffness and shroud configuration on the system natural frequency. For this purpose, natural frequencies of various systems (in terms of the position, where the blade is connected to the shroud and number of blades, which are connected together with a shroud) via different degrees of shroud stiffness and different configurations of shroud have been compared to show how this parameters affect the natural frequencies of the system. In this study, the shrouds have been considered as the discrete springs with corresponding stiffness values. The vibration frequency characteristics have been analyzed, using assumed mode method along with Hamilton’s law. Since in multi blade systems such as turbines it is crusial to keep the system working frequencies far away from natural frequencies (in order to prevent the resonance phenomenon), based on the results of this paper, it is shown how the parameters of shroud can remove the natural frequencies associated with some of the modes of the system from the work area.
