Nonlinear behaviour of tangled metal wire particle dampers

Tangled metal wire (TMW) dampers are constructed from coiled metal wire through a weaving/knitting and compression process. The material is also sometimes known as metal rubber or metal mesh. Under cyclic loading, it provides energy dissipation from friction within the microstructure and is interesting as its performance is not sensitive to temperature. It has been shown that small particles of this material that have not been subjected to the final compression process can still provide useful levels of damping. This paper reports investigations into the hysteresis arising from the loading of individual TMW particles and the energy dissipation performance of rigid containers filled with TMW particles. Behaviour when vibrated is found to be somewhere between polymeric granular dampers and classical solid metal particle dampers. Low frequency, cyclic compressive tests are carried out to identify the mechanical hysteresis of individual particles. This has revealed significant variability in the stiffness of individual particles and loss factors in the range 0.2 to 0.45 have been found. Over the range of deformations considered, the particles show softening behaviour. Drop and rebound tests conducted to identify energy loss at higher deformation rates show loss factors of approximately 0.15. Real and imaginary power measurements are made for a rigid cavity filled with TMW particles as it is subjected to different vibration signals. This damper is also applied to a vibrating structure. In this configuration, the particles generate very little damping. However, when the particles are used to fill a box-beam, significant damping is observed.