Sound and vibration of railroad wheel

Vibrations generated at the contact surfaces between rails and wheels have been considered to be the main cause of noise from railroad vehicles. These noises are classified into three types: rolling, impact, and screech noise. The generation mechanism of each noise has not yet been clarified. This study includes the calculation of natural frequencies of wheels based on elasticity theory, the laboratory test to measure the natural frequencies, the field test to measure the sound and vibration of a railroad wheel, and the analysis on the correlation between sound and vibration. Previous studies have not shown an explicit relationship between sound and vibration of a railroad wheel. The goal of this research is to explain noise from wheels by analyzing such a direct correlation. The result of this study designates that the origin of screech noise on a curved track comes from the lateral vibration of the wheel, and suggests that the vibration of the wheel has little direct contribution to rolling noise on a straight track.