On the rolling noise generation due to wheel/track parametric excitation

As a discretely supported railway track is essentially periodic, when a wheel rolls over the rail, it experiences the varying dynamic stiffness in a sleeper bay of the track, and thus the wheel and rail is periodically excited at the sleeper-passing frequency. The parametric excitation due to the varying track stiffness, in addition to the roughness or discontinuities on the wheel and rail rolling surfaces, also causes vibration and noise emission. A frequency–time domain methodology is applied for simulation of the wheel/rail interaction due to the parametric excitation. The wheel/rail interaction forces are calculated and Track–Wheel Interaction Noise Software (TWINS) is used to predict the noise radiation due to the parametric excitation at various train speeds. The results are compared with those from a moving irregularity model where no parametric excitation is generated. It is found that the components due to the parametric excitation are not significant at lower speeds compared with those due to the roughness excitation. Use of a moving irregularity model without considering the wheel/track parametric excitation may under-estimate the noise emission level at high speeds.