Particle impact damping

Particle impact damping (PID) is a means for achieving high structural damping by the use of a particle-filled enclosure attached to the structure in a region of high displacements. The particles absorb kinetic energy of the structure and convert it into heat through inelastic collisions between the particles and the enclosure, and amongst the particles. In this work, PID is measured for a cantilevered aluminium beam with the damping enclosure attached to its free end; lead particles are used in this study. The effect of acceleration amplitude and clearance inside the enclosure on PID is studied. PID is found to be highly non-linear. Perhaps the most useful observation is that for a very small weight penalty (about 6%), the maximum specific damping capacity (SDC) is about 50%, which is more than one order of magnitude higher than the intrinsic material damping of a majority of structural metals (O(1%)). Driven by the experimental observations, an elementary analytical model of PID is constructed. A satisfactory comparison between the theory and the experiment is observed. An encouraging result is that in spite of its simplicity, the model captures the essential physics of PID. (C) 2000 Academic Press.