Development of master design curves for particle impact dampers

by Yang, Michael Yichung.

iii Particle impact dampers (PIDs) are enclosures partially filled with particles of various sizes, shapes, and materials. When attached to a vibrating structure, they dissipate energy through inelastic collisions between the particle bed and the enclosure wall. In this thesis, the development of master design curves to predict the damping and mass characteristics of particle impact dampers are presented. A power measurement technique enabled the time-efficient measurement of the damping and mass properties of the PID. The power measurement technique enjoys several advantages over traditional loss factor measurements, including the flexibility to analyze the behavior of the PID at any frequency or excitation amplitude, and the ability to predict the damping and mass contribution for any structure operating under the same conditions. Using this power measurement technique, a large number of experiments were conducted to determine the effects of vibration amplitude, excitation frequency, gap size, particle size, and particle mass on the dissipated power and effective mass of the PID. A high speed digital video camera was used to directly observe particles in motion under different conditions, which greatly aided the interpretation of the data trends and the development of the master design curves. Based on the data trends from the power measurements and the insight gained from the videos, the power data was systematically collapsed into a pair of twodimensional master design curves with unitless axes which are comprised of combinations of design parameters. The damping and mass efficiencies of the PID may be predicted from the design curves for specific applications. An interpretation of the iv design curves is given, and the performance of a PID on a structure is used to verify their predictive capabilities.