Comparison of DEM predictions and measured wall-media contact forces and work in a vibratory finisher

Abstract

Discrete element methods (DEM) have been widely used in predicting the behavior of vibrated granular media, including that in vibratory finishing (VF) processes. In VF loose abrasive particles are fluidized by a vibrating container and the particle vibration work on the surface of parts entrained in the granular bed. In the present work, DEM was used to predict the forces exerted by the container walls on the granular media and the results were compared with previous experimental measurements performed with varying frequencies of vibration and amounts of media in the container. It was found that the overall trends in the DEM simulations were comparable to the experiments results, in that wall forces increased significantly with frequency but less so with increasing media mass. This was attributed to the viscous forces of granular media deformation, which generated wall forces that tended to increase with increasing media deformation rate and with increasing media pressure, although these trends were less pronounced in the DEM models than in the experiments. The DEM predictions of the contact force magnitudes were, however, well predicted in only two of the three container locations. The DEM predictions were also characterized by much larger cycle-to-cycle variations in the wall-media contact behavior than was observed experimentally. This included the presence of apparently random vibration cycles without any wall-media contact, which were not present in the actual force measurements.