The brake noise of tread-braked trains consists of broad band noise, mainly radiated by the brake system, and tonal squeal, mainly radiated by the wheels. The mechanism of squeal generation can be studied with a finite element model based on the binary flutter model with a constant friction coefficient, in a similar way as for disk and drum brakes. The broad band noise is probably a combination of judder (forced vibrations due to roughness) and knock (impact motion of brake parts mounted with play). The relative importance of these sources seems to be different for every brake design and depends strongly on the brake block material. Some measures for noise abatement are shown. Avoiding play in the structure is an effective measure to reduce knocking noise of multi-block configurations. Squeal can be reduced by applying a smart wheel damper. Both squeal and broad-band noise can be abated by sprinkling water in the contact surface or by applying an alternative brake block material. On the basis of theory, disturbing the rotational symmetry of the wheel by adding localized masses or stiffnesses is likely to be effective for squeal reduction. More research is needed to map the relative importance of the different brake noise sources in field situations. Progress in the modelling of brake squeal can be made by carefully choosing a study object, preferably a test rig in controlled laboratory conditions.
A study on the brake noise of tread-braked trains
Untersuchung des Bremsgeräusches von laufflächengebremsten Zügen
International Congress on Sound and Vibration, 7 ; 2655-2662
2000
8 Seiten, 2 Bilder, 14 Quellen
Conference paper
English
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