Effect of Coulomb Friction on the Vibrations of a System with Elastically Supported Viscous Damper : 1st Report, Free and Transient Vibrations

Abstract

In this report, the effect of Coulomb friction brought about from the packing gland of the damper on the free and transient vibrations of the above system is considered with respect to some numerical examples. The result shows (1) that a cycle of free vibration consits of two motions, one the motion when the friction is infinite and the other the motion with combined Coulomb friction and viscous damping, and (2) that the transient state while the system runs over a bump (shaped like a portion of sinusoidal curve) is regarded as a chain of fragmentary pieces of the two kinds of motion stated above. The existence of the motion when the damper is momentarily stuck-up gives a negative effect on the diminishing of the amplitude of the free-vibration of the system, but comparing the transient states with those of the system with no friction, a larger decrement of the amplitude of the initial response may occur in some cases according to the combination of the magnitude of friction, height of projection and the passing speed over it.