Interface - The Journal of Wheel/Rail Interaction

WHEEL NOISE

Tuning Mass Dampers to Reduce Squeal
By Paul Kampfraath • January, 2007

Wheel/rail-generated squeal presents a nuisance on urban rail systems. Wheel squeal is consistently identified as one of the more vexing "political" and "engineering" issues that urban rail system operators must deal with. Noise and vibration issues are such that there are research programs and technical committees devoted to them.

The use of rail gauge-face lubrication and top-of-rail friction modifiers represents the most common approach to treating squeal noise. Another, less familiar, method is the use of tuned mass dampers that are mounted on the wheel. Rail systems such as the Rotterdamse Electrische Tram (RET) in the Netherlands have chosen this approach to deal with squeal. The RET, which operates a mixed vehicle fleet, mounted tuned mass dampers on the wheels on 60 of its Alstom CITADIS™ three-bogie light rail vehicles.

A tuned band mass damper, that provides broad band noise reduction, consists of a series of steel plates that are held together under tension (which varies with a system's requirements) by an elastic material. The system works by absorbing vibration energy and converting it through friction into other energy forms, such as heat, in a three-dimensional direction. (Tuned mass dampers can also be used to convert vibration into other energy on track structures and steel bridges.)

The tuned mass damper wheel absorber is bi-functional. It is designed to reduce rolling noise and reduce, or eliminate, squealing noise. The design of the noise-reduction system, however, depends on the types of vehicles, track design and the operational parameters of a given rail system. These parameters, along with various vehicle/track-specific issues, must be addressed for successful implementation of a tuned mass damper, noise-reduction system.

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