An experimental investigation into the use of a buffered impact damper

An impact damper is a freely moving mass, constrained by stops, located on a dynamic structural system to be controlled. As the system is excited, the impact mass moves relative to the structure resulting in impacts between the mass and the stops, transferring momentum from the structure to the impact mass, and dissipating energy as heat, noise and high frequency vibrations. At the point of impact, large accelerations are imparted to the structure, which may be undesirable, particularly for occupied structures. In order to reduce these high accelerations, it is proposed to incorporate a buffer region between the mass and the stop. Free and forced vibration tests of a system equipped with a buffered impact damper are used to study the resulting damping effect and impact characteristics. The performance of the buffered impact damper is compared with that of a conventional rigid impact damper. It is found that the buffered impact damper not only significantly reduces the accelerations, contact force and the associated noise generated by a collision but also enhances the level of vibration control. A possible reason for the enhanced control is postulated by examining impact behaviour. The investigation shows that the effective reduction of the vibration response depends not only on the magnitude of the contact force but also upon the contact time.