Damping mechanisms of vibration reduction system with granular materials for vibration system with high natural frequency (Proposal of “relative motion mass”, “rotating mass”, and their consideration)

Abstract

We investigated the damping mechanism of a granular material damping system applied to reducing vibration in structures that have a high natural frequency and small vibration displacement. Experiments were conducted under several conditions of total mass of granules. We also constructed a computational model of a single-degree-of-freedom vibration system with a granular material damper to study the mechanism of a granular material damping system. On the basis of the fundamental idea that the damping effect of a granular material damper is governed by the motion of the granules, we classified the granular materials as “relative motion mass” and “equivalent added mass” in the translational motion and as “rotating mass” and “not rotating mass” in the rotational motion and then considered the relationship of these mass classes to the damping characteristics. In this report, we examine the relationships of the motion of the granular materials, “relative motion mass” and “rotating mass”, and damping ratio by means of experiments and calculations for structures that have a high natural frequency and small vibration displacement.