Irreversible energy transfers in systems with particle impact dampers

In this work, irreversible energy transfers from a linear oscillator (designated as “primary structure”) forced by shock to a strongly nonlinear attachment composed of particle impact dampers (PIDs) are investigated. The attachment is in the form of a rigid cavity filled with differing quantities of granules; the elastoplastic collision modeling the granule-to-granule and granule-to-cavity interactions adopts a Hertzian contact law in the axial direction and a Coulomb slipping friction law in the tangential direction. The discrete element method, capable of simulating convergence and accurate energy conversion, is utilized to simulate the strongly nonlinear dynamics of the PIDs. Of specific interest are the irreversible energy transfers from the primary structure to the PIDs and the dependence of these transfers on the specific PID configurations. It is concluded that, for the same number of granules in the PID, drastic differences in energy transfer exist depending on the initial topology of the granules. To this end, symmetric and asymmetric topologies in which clearances are introduced are proposed for the considered PIDs. In addition, the effect of the size of the PID cavity is studied, and interesting correlations between irreversible energy transfer and granular dynamics are revealed. Accordingly, energy transfer for granular motions in the gas regime is less effective compared to a collect-and-collide regime, which leads to significant energy transfer. The perspective of irreversible energy transfers reported herein provides strong motivation for developing the next generation of PID technology.