NOISE GENERATION IN RAILWAY WHEELS DUE TO RAIL-WHEEL CONTACT FORCES

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Abstract
In urban rapid transit systems the squealing noise of railway wheels during the passage through narrow curves is very troublesome to passengers and city dwellers. Frequency analyses of measured curving-noise levels show that the bending vibrations of the wheel disks excited by stick-slip motion between the wheel rim and the rail are the main sources of this sound radiation. To get insight into the dynamics of the noise generation it is necessary to understand the bending vibration behaviour of a wheel disk as well as the sound radiation mechanism and the generation of self-sustained oscillations in the contact area. The present paper deals with a theoretical model which comprises all three parts of the problem. In the first part the natural bending vibrations of the wheel are calculated by means of a finite element model. In the second part the forced and self-sustained oscillations are determined using modal expansion techniques. The third part deals with the calculation of the radiated sound pressure and sound power due to wheel oscillations. Here, an acoustical quality level is introduced to classify the various types of wheel disks. The major assumptions in the present paper are rigid rails and point contact between wheel and rail.