Particle Dampers- Enhancing Energy Dissipation using Fluid/Solid Interactions and Rigid Obstacle-Grids

Particle dampers (PDs) are a promising alternative to conventional dampers, due to their simple design and their flexible ability to dissipate energy over a wide frequency range. One of the disadvantages of conventional PDs is, that their efficiency is highly dependent on the forcing function. In this thesis, two strategies to enhance the low amplitude damping performance of PDs are pursued. Firstly, the possibility of partially filling the PD container with a liquid to increase the damping performance is explored. To better quantify the influence of parameter changes, simulation and experiments are conducted. The liquid motion is modeled using the smoothed particle hydrodynamics (SPH) method and the discrete element method (DEM) is used to model the motion of the solid particles. Experimental and simulation results show that dampers with a combination of solid and liquid filling exhibit superior energy dissipation than purely solid-filled or purely liquid-filled dampers, particularly under low excitation amplitudes. Moreover, the effect of non-convex particle shapes in the context of a partially liquid-filled PD is investigated. The second enhancement strategy pursued in this thesis involves the introduction of an 3D obstacle-grid in PDs. Apart from the excellent agreement between experiments and simulation, it is seen that the damping performance of a PD with a obstacle-grid is at least twice as good as a PD without an obstacle-grid. Results show that particles that would have otherwise been hardly contributing to energy dissipation, move violently due to an obstacle-grid, and hence actively participate in the energy dissipation process. Finally, the PD is applied to a weakly damped vibrating frame structure, with the focus of analyzing the broadband damping of PDs.