Vibration Control Using an Impact Damper System: Comparison between Translating Impactor and Rotating Impactor, and Improvement of Rotating Impactor

Impact damper systems are used to reduce the vibration of a lightly damped resonant primary system. The impact damper consists of an impactor and a container. The container is attached to the mass part of the primary system. The container mainly consists of two walls, and the impactor is placed inside the container. And since the impactor is free to move in the container, the impactor collides with the walls. When the impactor collides, some of the vibration energy of the primary system is momentarily converted to kinetic energy of the impactor. That is, impact damper system is damper which utilizes this energy conversion by impact phenomenon. We compared the damping characteristics in an impact damper system between a translating impactor and a rotating impactor and found that the rotating impactor is superior to the translating impactor. Then, with the aim of improving the damping characteristics of the rotating impactor, we proposed that an eccentric mass be added to the rotating impactor and confirmed that the damping effect improves because of the eccentric mass. Next, we calculated the mechanical energy of a vibration system having an impact damper and investigated the mechanism behind this improvement in damping characteristics due to the eccentric mass. In particular, we classified the impacts that occur between the impactor and wall into three types and examined the change in energy of the primary vibration system immediately after such impacts. In this way, we clarified the mechanism behind improved damping effect due to the addition of an eccentric mass.