Energy Transfer of Particle Impact Damper Systems

In this work, investigations on energy transfers from a linear oscillator (called primary structure) forced by a shock to a strongly nonlinear attachment, namely a particle impact damper (PID) are carried out. The granules inside the cavity of the PID are arranged in initial topology with clearances. The granular interactions are realistically modeled by combining a Hertzian dissipative contact model and a Coulomb-tanh friction model, which is useful to accurately explore the strong and highly discontinuous nonlinear characteristics of this system subject to shocks of varying intensities. The discrete element method is employed for these simulations, considering granular translations and rotations. Generally, by optimizing the size of the cavity one can improve the shock mitigation performance. The capacity of energy transfer and energy dissipation in the granular medium is enhanced and maintained by a collect-and-collide regime. Intense nonlinear contacts via granule-to-granule and granule-to-wall interactions result in intense and irreversible energy transfer of shock energy from the directly forced primary structure to the PID. Once this energy is transferred, it gets efficiently scattered to high frequencies and dissipated by the inelastic granular collisions and frictional effects due to relative granular rotations. The energy transfer reported herein provides strong motivation for developing the next generation of PID technology.