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Repetitive collision occurring between structural and machine components is a topic of practical and scientific importance. Some types of machinery are inherently susceptible to impacts because of the small clearances present between adjacent components, thermal expansion, and relative motion as in gear trains. One can observe repetitive impacts in milling machines, shakers and off-shore structures. Energy transfer between components that are subjected to repetitive impacts is a complex phenomenon that often exhibits deceptive and non-intuitive behavior. Even in seemingly simple structures, period-doubling bifurcations, sub-harmonic resonances, and chaotic responses occur. This paper presents detailed experimental data obtained from an impact vibration test stand that was instrumented for displacement, velocity, and impact force measurements. In addition, the apparatus was fabricated in such a way to allow for precise positioning of the impact point, and varying of the gap distance between impacting components. The paper includes companion simulation results obtained from a model for the repetitive impact dynamics of otherwise linear single or multiple degree of freedom discrete structures. Simulation results are presented for the effect of natural frequency placement, model dimension, and gap clearance on the qualitative and quantitative character of the response. Of particular interest is the transition of behavior as the system’s model is augmented from having one to several degrees of freedom.

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