Damping mechanisms of granular-material damper in structure with high natural frequency (Study of flow of vibration energy)

Abstract

We investigated the damping mechanism of a granular-material damper for a structure with a high natural frequency. We focused on the flow of the granular-material vibration energy and considered its relationship with the damping characteristics. The movement of spherical granular materials was calculated in the granular-material damper; the power of the collision force and the frictional force exerted by the granular materials on the primary vibration system were obtained and compared with the input energy. In the region in which the total mass of the granular materials was small, the collision force that the granular materials exerted on the primary vibration system affected the damping characteristics of the granular-material damper. Conversely, in the region in which the total mass of the granular materials was large, the frictional force that the granular materials exerted on the primary vibration system in addition to the impact force affected the damping characteristics of the granular-material damper. That is, the vibration of the primary vibration system is primarily affected by the collision of the granular materials on the left and right container walls, and by the energy consumption caused by the friction of the granular materials on the bottom of the container. By using the quantities of energy consumed in both collisions and frictions, it is possible to evaluate the damping characteristics of the granular-material damper.

Keywords

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