Research on prediction of dynamics of impact damper with granular materials (The case of vertical vibration)

Abstract

The Impact damper with granular materials has a high damping effect for wide frequency range and it is used in many fields. Many researches have been made on the prediction of the damping effect of this damper on one degree of freedom spring-mass system. But it is more useful to be able to predict the damping effect when applied to a real complex structure. For this purpose, numerical modeling of damping effect of an impact damper is important for efficient design of structures set with dampers. In this paper, the granular materials are modeled as one mass point of restitution coefficient of zero that undergo displacement vibration excitation, and the motion of this mass point is theoretically analyzed for the case of vertical vibration and one side collision. From these results, we propose a method for obtaining the macroscopic damping effect of the impact damper with granular materials. This is obtained as a nonlinear equivalent mass ratio and nonlinear damping coefficient with amplitude dependence. Further the excitation experiment which identified the damping characteristic of the damper was carried out. Theoretical solution and experimental result show the good coincidence.