Laboratory methods for testing the performance of acoustic rail dampers

Martin Toward , David Thompson

Several types of rail damper are now commercially available to reduce noise radiated by railway track. These dampers, attached to the rail between sleepers, increase the attenuation with distance of vibration transmitted along the rail (decay rate). Currently, there are no standardized procedures to measure the effectiveness of these dampers without the need for their installation in a track. Track decay rates of damped ‘freely’ supported rails have been measured using two proposed methods: (i) for short rails (4-6m length), at low frequency from the modal properties of the rail, and at high frequencies directly from point and transfer response functions (FRFs) at either end of the rail; and (ii) for long rails (15-32m), by integrating decay rates derived from FRFs measured at intervals along the rail. Results from four test institutes show generally good agreement between the two methods for three different damper designs. However, at some frequencies substantial inter- and intra- method variability is evident. Sources of this variability are identified and are discussed. Further tests conducted on a 32m test track show that decay rates of damped track can be reasonably determined by summing decay rates of the ‘free’ damped rail and those of the undamped track.

Mots clés: Rail Damping; Railway noise; Tuned absorber; Mitigation

Domaines: Acoustique [physics.class-ph]

Martin Toward, David Thompson. Laboratory methods for testing the performance of acoustic rail dampers. Acoustics 2012, Apr 2012, Nantes, France. ⟨hal-00810837⟩