Experimental study on dynamics of an oblique-impact vibrating system of two degrees of freedom

摘要

The paper presents a detailed experimental study of an oblique-impact vibration system of two degrees of freedom. The primary objective of the study is to verify the hypothesis of instantaneous impact in the oblique-impact process of two elastic bodies such that the incremental impulse method works for computing the nonlinear dynamics of the oblique-impact vibrating systems. The experimental setup designed for the objective consists of a harmonically excited oscillator and a pendulum, which obliquely impacts the oscillator. In the study, the dynamic equation of the experimental setup was established first, and then the system dynamics was numerically simulated by virtue of the incremental impulse method. Afterwards, rich dynamic phenomena, such as the periodic vibro-impacts, chaotic vibro-impacts and typical bifurcations, were observed in a series of experiments. The comparison between the experimental results and the numerical simulations indicates that the incremental impulse method is reasonable and successful to describe the dynamics during an oblique-impact process of two elastic bodies. The study also shows the limitation of the hypothesis of instantaneous impact in an oblique-impact process. That is, the hypothesis only holds true in the case when the impact angle is not too large and the relative approaching velocity in the normal direction is not too low. Furthermore, the paper gives the analysis of the tangential rigid-body slip on the contact surface in the case of a large impact angle, and explains why there exist some discrepancies between the numerical simulations and the experimental results.