Damping mechanisms of vibration reduction system with granular materials for vibration system with high natural frequency (Study for high damping)

Abstract

We investigated the damping mechanism of granular material dampers when using a structure with a relatively high natural frequency and small vibration displacement as the target of vibration damping. For powder or granular material dampers, the movement of the powder or granular material is the basic principle of damping. Damping ratios were calculated and compared by individually modifying each parameter (other than diameter) that affects the granule’s motion. As a result, it was found that when the moment of inertia of the granules is 1/2 and the Young's modulus is 1/100 of steel, the damping effect is improved in the region where the total body weight is heavy. In addition, as a specific example of reducing the moment of inertia and optimizing Young’s modulus, when the effect was examined by calculation and experiment using rubber ball with steel core, it was found that the damping ratio can be improved in the region where the total mass of the granules is large. Furthermore, we obtained new knowledge that the hardening spring characteristics of rubber balls containing steel balls have a positive effect on damping characteristics.

Keywords

• damper
• granular materials
• single degree of freedom system
• damping ratio
• collision force
• frictional force