Affiliations: Department of Mechanical Engineering, Kitakyushu
National College of Technology, Fukuoka, Japan | Professor Emeritus, Kitakyushu National College of
Technology, Fukuoka, Japan | Department of Mechanical and Control Engineering,
Kyushu Institute of Technology, Fukuoka, Japan
Abstract: A particle damper consists of a bed of granular materials moving in
cavities within a multi degree-of-freedom (MDOF) structure. This paper deals
with the damping effects on forced vibrations of a MDOF structure provided with
the vertical particle dampers. In the analysis, the particle bed is assumed to
be a single mass, and the collisions between the granules and the cavities are
completely inelastic, i.e., all energy dissipation mechanisms are wrapped into
zero coefficient of restitution. To predict the particle damping effect,
equations of motion are developed in terms of equivalent single
degree-of-freedom (SDOF) system and damper mass with use made of modal
approach. In this report, the periodic vibration model comprising sustained
contact on or separation of the damper mass from vibrating structure is
developed. A digital model is also formulated to simulate the damped motion of
the physical system, taking account of all vibration modes. Numerical and
experimental studies are made of the damping performance of plural dampers
located at selected positions throughout a 3MDOF system. The experimental
results confirm numerical prediction that collision between granules and
structures is completely inelastic as the contributing mechanism of damping in
the vertical vibration. It is found that particle dampers with properly
selected mass ratios and clearances effectively suppress the resonance peaks
over a wide frequency range.
Keywords: Vibration suppression, particle damper, multi degree of freedom system, modal analysis, periodic motion
