UBC Theses and Dissertations
Friction induced vibration Cameron, Roderick
Frictional vibrations have been induced in a system having an elastically suspended,and viscously damped slider loaded onto a surface driven-at constant velocity. Exact mathematical analysis-of the system reveals a unique value of the driven surface velocity, above which frictional vibrations of the slider cannot exist. Theory suggests that the "critical" value-of the driven surface velocity is dependent upon the damping, load, and stiffness of the suspension, and the friction characteristics-of the rubbing surfaces. Using the approximation that the amplitude of stick of the slider equals the maximum amplitude of vibration, a relationship is developed which predicts the amplitude of vibration at any given value of driven surface velocity. The limiting velocity of this function when the amplitude tends to zero is the critical velocity. Exact and approximate theories are compared for specific practical cases, and reasonable agreement is found. Five systems were investigated experimentally, and displacement-time charts of the slider were obtained at different values of the driven surface velocity. Unstable regions were noted where the slider fluctuated between smooth sliding and frictional vibrations. The experimental data illustrates the existence of a critical velocity of the driven surface, and its dependence upon the degree of damping in the system. The correlation between experimental data and theoretical curves indicates that the developed analytical method could be used to predict the behaviour of systems subject to friction induced vibrations.
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