Characteristics of micro fine copper particles impact damping

Abstract

Impact damping has been widely used in machine tools, robots, turbine machineries, aircrafts, and launch vehicles. Introducing micro fine particles into impact dampers may bring additional irreversible energy loss such as particle size reduction and plastic deformation for the damping, and carve out a new way to control the motion. For this purpose we use copper particles with an average size of 50 μm in ball impact dampers installed on a cantilever subjected to sinusoidal vibration within 96-hour impacting, and test the damping characteristics. We show that the response of the primary system can be divided into three stages, i.e., increasing, then deceasing, and increasing again. This dynamic feature reflects the deformation behaviors of the micro copper particles in different stages. In the first stage, the copper particles may display elastic behavior, and the sub-harmonic vibration of the steel ball may return part of the energy back to the primary system and enhance the response. In the second stage, the copper particle is forced into its yield point and the plastic deformation exhausts the energy and response of the system decline. In the third stage, hardening effect of the copper particles occurs and the response of system increases again. Our results may be significant to passively control the vibrations and material deformation.