Abstract
This paper examines the characteristics of the low frequency vibration which occurs in a vibroimpact system. The system investigated comprises two masses which can move only in the vertical direction under gravity. The lower mass is supported by a spring and subjected to a periodic exciting force whereas the upper mass bounces freely on the lower mass. The results show that the induced frequency is close to the natural frequency of the whole system when the ratio of the upper mass to the total mass is small, and gradually decreases with the increasing mass ratio. In order to clarify the mechanism of the frequency decrease, the analysis is made on the behavior of the variation, demonstrating that the collision between masses induces the instantaneous phase delay of free vibration component and its effect increases with the mass ratio.
