Parameter dependence of the impact dynamics of thin plates

Abstract

Noise generation by the impact of thin plates is an example of energy transfer from the low frequency vibration of the fundamental modes to high frequency vibration modes. The noise radiation from the impact is determined by the impact dynamics. In this paper, we extract low-dimensional models for the impact dynamics. Detailed analysis is conducted on a single-degree-of-freedom system. Qualitative understanding of the dynamic behavior is achieved through the bifurcation sets which represent the partition of the parameter space into qualitatively different regions. It is found that many (possibly infinite) periodic solutions bifurcate from the grazing bifurcation point. Most of these periodic orbits terminate at secondary grazing bifurcations. The impact dynamics influences the impact velocity tremendously. The ‘nominal impact velocity’ which designers might use as a reference can be very different from the actual impact velocity. Experiments are conducted on a thin plate impacting a striker. The experimental observation that the impact when forced above resonance frequency is stronger (larger impact velocity and larger sound pressure level) than forced below resonances agrees with the theoretical predictions. Data on both the impact velocity and the noise level are acquired.