Abstract

Vibration control is important in the design of light, efficient and environmentally acceptable machines and structures. While polymers are widely used as the energy dissipating element in damper designs, they are often unsuitable for the operating environment that might include extreme temperature, pressure and radiation.

Fragmented material dampers (FMDs) involve many small fragments that can move a small distance relative to each other under dynamic loading, but are held together by a frame, substrate or enclosure. Energy is dissipated via sliding friction at the numerous contact points. FMDs offer vibration control over broad temperature and frequency ranges and can be made from materials that survive in harsh environments. Because energy dissipation comes from sliding friction, FMD performance is sensitive to the static and dynamic strain applied. Increasing dynamic strain activates the damper: the loss factor increases while the stiffness drops. Higher static strain however, reduces the level of activation and therefore increases stiffness.

This talk considers the performance of several FMDs including tangled metal wire, thermally sprayed ceramic and granular dampers. This includes consideration of material characterisation, and the development of models that can be used in component design.