Analytical modeling of distributed array of resilient particle impact dampers

Particle impact dampers (PIDs) or shot mass dampers are known to provide high loss factors on vibrating structures by dissipating kinetic energy through particle-enclosure and particle-particle collisions. The rate of energy dissipation is amplitude dependent, which makes the particle damping highly nonlinear. Previous studies have focused on horizontal excitation (perpendicular to gravity) for particle damping. Vertically excited systems (parallel to gravity) have also been studied in the literature, in which the excitation has generally been considered to be harmonic. However, harmonic disturbances do not accurately represent some cases where repetitive impacts occur, such as manufacturing and maintaining aircraft structures with the operations of riveting and chiseling. This study is concerned with developing analysis methods for PIDs under periodic impulse excitation in the vertical direction. Impulse excitation differs from harmonic excitation in the sense of response modeling. Systems under harmonic excitation are subject to forced-response, whereas the effect of an impulse excitation is equivalent to the effect of an initial velocity condition at the impulse application time, and a free decay until the next impulse. Therefore, the systems considered herein are inherently in free-response and unforced between impulses. Particle damping is analyzed for i) a single resilient PID, ii) a cantilever beam with arrays of PIDs attached to various locations on the beam, and iii) a simply supported plate with arrays of PIDs attached to various locations on the plate. These analyses are used for an optimization of a distributed array of PIDs on a cantilever beam and on a simply supported plate.Ph.D