Experimental validation of a ball-balancer model for washing machines using FSI analysis methods

Vibration in a washing machine mainly occurs due to the rotational eccentricity from its unbalanced mass. Since severe vibration and noise degrades the quality of products, a ball balancer often installed in washing machines in addition to springs and dampers. A ball balancer is known to have the better performance than the other existing ones in vibration reduction, but also has difficulties in analysis of its operation since it contains both fluid and structure behaviors at the same time. The purpose of this paper is to analyze drag force between the ball and fluid in a ball balancer of washing machines. To add ball balancer model in the multibody washing machine modeling, fluid drag force should be required to complete dynamic modeling of washing machines. To match this goal, both computer simulation and real experiment are compared to accurately model the fluid drag force. To analyze fluid-structure interaction in a ball-balancer used in washing machines, commercial programs with FSI (fluid structure interaction) can be used. To measure the motion of a ball in a ball-balancer, a transparent tube including several balls and fluid was manufactured. The input property and operation condition for computer simulation were obtained from experiment. Modeling was analyzed with FSI technique in ABAQUS program. The velocity of a ball was constrained with an input, and the reaction force acting on the ball was measured. Simulation results were compared to experimental results. A ball in an experimental tester had shown slightly different behavior depending on rotational speed of a jig. Results from analysis and test were in good agreements. Since the FSI analysis was reasonable, other information for diverse balancer models could be obtained from analytical models. Copyright (c) 2010 by JSME.