EFFICIENCY OF VIBRATIONAL-ENERGY DISSIPATION BY MOVING SHOT

The paper presents measuring methods and measurement results of vibration damping of shot-filled containers with some empty volume as the shot damper clearance. The energy dissipation by shot depends on two phenomena: the internal and the external (container walls) impacts of shot particles associated usually with their internal and external friction. This is the working principle of the single-/multi-mass impact dampers and the shot vibration damper as well. It is shown in the paper that the additional loss factor introduced by the shot moving in the properly shaped container is on the order of half of shot mass reduced to the primary system modal mass. It may be even twice more if the energy dissipation by shot friction will be fully utilized. This depends mainly on the motion condition of shot inside a container. It was shown in the paper also that loose shot or better shot tightly packed in a plastic bag or mesh can fulfill this condition. Shot dampers can work efficiently in a broad range of acceleration and frequency and need not be maintained. Due to this it may be very convenient to apply them to structural vibration problems.