The Effect of Wheel Rotation on the Rolling Noise Predictions

The effect of the wheel rotation on its sound radiation in rolling noise predictions is investigated. The wheel response is modelled using a finite element model that can account for the different effects introduced by rotation and together with TWINS the radiated sound power is determined. Noise and vibration data are compared over a range of typical train speeds, between a stationary wheel, a rotating wheel where rotation is replaced by a moving load, and a rotating wheel that also includes the inertial forces. Compared with the most complete model, differences in the wheel sound power level of up to 6 dB in one-third octave bands are found if the stationary wheel is used instead. The differences remain below 2 dB for speeds up to 500 km/h if the rotation is approximated with a moving load. In terms of the total A-weighted sound power level of the wheel, the stationary wheel underestimates the noise by up to 3 dB, while the differences are less than 1 dB for a moving load. Generally, the differences introduced by the approximate representations of the wheel rotation are smaller than the uncertainties that are inevitable in rolling noise predictions. The results show that in rolling noise predictions for usual train speeds the wheel rotation is sufficiently well approximated by a moving load, which is the method implemented in TWINS.