The effectiveness of the impact damper with granular material

The multiple -particle impact damper consists of a bed of granular materials moving in a container fixed to the resonantly vibrating system. This type of impact damper substitutes for the solid impact damper that causes excessive noise in its operation, and deteriorates the damping performance under gravity. The problem is to determine the effectiveness of the impact damper with granular materials as a damper mass, for reducing the vibration of a single degree-of-freedom system to a prescribed value when the excitation is simple harmonic. In the analysis, the particle bed is assumed to be a mass which moves uni-directionally in a frictionless container and collides plastically with the ends of container. The solutions for some possible types of the steady state impact motions, and frequency response are obtained. This study deals with the two different cases, i.e., the dampers are applied to a vertical and a horizontal vibrating systems. Experimental models were tested to verify the analysis, and further to modify them for the case of the horizontal system.