Jules Metsebo | University of Yaounde I (original) (raw)
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Papers by Jules Metsebo
Nonlinear Dynamics, 2014
ABSTRACT The problem of minimizing the dynamics response of a damped cantilever Timoshenko beam s... more ABSTRACT The problem of minimizing the dynamics response of a damped cantilever Timoshenko beam subjected to earthquake excitation is investigated in this paper. The ground acceleration is expressed in terms of a Fourier series that is modulated by an enveloping function. The method of lines and modal approach are developed for analyzing the eigenvalues and the flexural vibrations. A magneto rheological damper is proposed to reduce the vibration of the structure. The device is localized at a specific point of the beam. A modal shape which characterizes the vibration of the uncontrolled and controlled system is obtained. The condition of stability of the controlled system is derived using the Routh–Hurwitz criterion.
This work is focused on development of model for unbalanced rotor bearing system to predict syste... more This work is focused on development of model for unbalanced rotor bearing system to predict system behaviour in dynamic environment. In this model, nonlinearity is introduced due to two factors, namely, clearance of bearing and localized bearing races defects. The contact between the races and balls is considered as Hertzian contact which results in nonlinear restoring force due to elastic deformation in contact zone. In the mathematical formulation, the shaft is considered as rotating Timoshenko beam, supported on two ball bearings. After modelling of shaft corresponding equations representing the system behaviour has been formulated. The governing equations of motion are solved by Sixth order Runge-Kutta method. Bifurcation plots have been plotted to understand the state of the system in healthy condition and due to localized defects on races of the bearings. The Frequency spectrum and phase trajectory diagrams are also plotted for better understanding of the system response.
Nonlinear Dynamics, 2014
ABSTRACT The problem of minimizing the dynamics response of a damped cantilever Timoshenko beam s... more ABSTRACT The problem of minimizing the dynamics response of a damped cantilever Timoshenko beam subjected to earthquake excitation is investigated in this paper. The ground acceleration is expressed in terms of a Fourier series that is modulated by an enveloping function. The method of lines and modal approach are developed for analyzing the eigenvalues and the flexural vibrations. A magneto rheological damper is proposed to reduce the vibration of the structure. The device is localized at a specific point of the beam. A modal shape which characterizes the vibration of the uncontrolled and controlled system is obtained. The condition of stability of the controlled system is derived using the Routh–Hurwitz criterion.
This work is focused on development of model for unbalanced rotor bearing system to predict syste... more This work is focused on development of model for unbalanced rotor bearing system to predict system behaviour in dynamic environment. In this model, nonlinearity is introduced due to two factors, namely, clearance of bearing and localized bearing races defects. The contact between the races and balls is considered as Hertzian contact which results in nonlinear restoring force due to elastic deformation in contact zone. In the mathematical formulation, the shaft is considered as rotating Timoshenko beam, supported on two ball bearings. After modelling of shaft corresponding equations representing the system behaviour has been formulated. The governing equations of motion are solved by Sixth order Runge-Kutta method. Bifurcation plots have been plotted to understand the state of the system in healthy condition and due to localized defects on races of the bearings. The Frequency spectrum and phase trajectory diagrams are also plotted for better understanding of the system response.