Impact vibration of beams was treated as an example of the impact vibration of a continuous system and the following points were researched: (a) The number of modes to express the impact vibration phenomena sufficiently. (b) The affect of damping on the impact vibration of beams. The following points were made clear through this research: (1) By adopting six beam modes and using Hongo's collision model with velocity dependent coefficient of restitution, the theoretical and experimental results agree well each other qualitatively. (2) The dampings of higher beam modes and accordingly behavior of those modes strongly influences bifurcation. (3) In the beam with larger damping, chaos occurred after period double bifurcations, on the other hand, in the beam with smaller damping, chaos occurred after torus doubling. From the viewpoint of engineering, the transition from periodic motion to chaos is interpreted as the grazing bifurcation which is recognized in the impact vibration system of particles.
