THEORETICAL AND EXPERIMENTAL MOTION ANALYSIS OF SELF-COMPENSATING DYNAMIC BALANCER

A theoretical and experimental approach was used to investigate the mo tion and effectiveness of a Self-Compensating Dynamic Balancer(SCDB). This is a device intended to minimize the effects of rotor imbalance a nd vibratory forces on a rotating system during normal operation. The basic concept of an automatic dynamic balancer has been described in m any U.S. patents. The SCDB is composed of a circular disk with a groov e containing massive balls and low viscosity damping fluid. The object ive of this research is to determine the motion of the balls and how t his ball motion is related to the vibration of the rotating system usi ng both theoretical and experimental methods. The equations of motion of the balls were derived by the Lagrangian method. Static and dynamic solutions were derived from the analytic model. To consider the dynam ic stability of the motion, perturbation equations were investigated b y two different methods: Floquet theory and direct computer simulation . On the basis of the results of the stability investigation, ball pos itions which result in a balance system are stable above the critical speed and unstable at critical speed and below critical speed. To dete rmine the actual critical speed of the rotating system used in the exp erimental work, a modal analysis was conducted. Experimental results c onfirm the predicted ball positions, Based on the theoretical and expe rimental results, when the system operates below and near the first cr itical speed, the balls do not balance the system. However, when the s ystem operates above the first critical speed the balls can balance th e system.