Prediction methods for the damping effect of multi-unit particle dampers based on the cyclic iterations of a single-unit particle damper

Particle damping (PD) has been successfully utilized in numerous aerospace and industrial applications. However, compared with the well-studied single-unit multi-particle dampers, multi-unit multi-particle dampers (MUPDs) have seldom been investigated because of the complex interactions among different damping units. This research presents two damping effect prediction methods that are based on the cyclic iterations of the damping effect of a single-unit particle damper. The first is a numerical method that uses the discrete element method, and the other is a semi-empirical method that adopts damping ratio versus normalized acceleration curves for PD. In both methods, interactions among dampers at different locations are considered. The damping effects of six different MUPDs applied to a wheel structure were experimentally investigated. Four of them, which were named multi-stage MUPDs, consisted of groups of dampers mounted at various radial location (The dampers were located at positions of different acceleration amplitudes.). The damping prediction results of the two proposed iteration methods, together with those of a simplified method that regards the MUPD as a single-unit particle damper with same equivalent particle mass ratio, were compared with experiments. Significant improvements in prediction accuracy for the two iteration methods were observed.