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Shock and Vibration
Volume 14 (2007), Issue 2, Pages 151-167

Dynamic Analysis of a Pendulum Dynamic Automatic Balancer

Jin-Seung Sohn,1 Jin Woo Lee,2 Eun-Hyoung Cho,1 No-Cheol Park,3 and Young-Pil Park2

1Storage Laboratory Samsung Advanced Institute of Technology, P.O. Box 111, Suwon 440-600, Korea
2Department of Mechanical Engineering, Yonsei University, 134 Shinchon-dong, Sudaemun-ku, Seoul 120-749, Korea
3Center for Information Storage Device, Yonsei University, 134 Shinchon-dong, Sudaemun-ku, Seoul 120-749, Korea

Received 4 June 2004; Revised 16 May 2005

Copyright © 2007 Hindawi Publishing Corporation. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


The automatic dynamic balancer is a device to reduce the vibration from unbalanced mass of rotors. Instead of considering prevailing ball automatic dynamic balancer, pendulum automatic dynamic balancer is analyzed. For the analysis of dynamic stability and behavior, the nonlinear equations of motion for a system are derived with respect to polar coordinates by the Lagrange's equations. The perturbation method is applied to investigate the dynamic behavior of the system around the equilibrium position. Based on the linearized equations, the dynamic stability of the system around the equilibrium positions is investigated by the eigenvalue analysis.

The stability analysis provides the design requirements for the pendulum automatic dynamic balancer to achieve a balancing of the system. The efficiency of ball automatic dynamic balancer, for reducing the total vibration of the system, is better than one of pendulum automatic balancer, if the rotating speed is above critical speed. However, pendulum automatic dynamic balancer can achieve balancing even if the rotating speed is below critical speed.

The time response analysis demonstrates the stability analysis from computing the radial displacement of the rotating system and the positions of pendulums. Furthermore, in order to confirm the theoretical analysis, various experiments are made on pendulum automatic dynamic balancer.