A correlation study of vibration and noise signals by analyzing its responses for monitoring of high-speed trains

In high-speed trains, vibration has long been an inevitable problem caused by many ambient effects, including wheel polygonization, rail defects, imperfect suspension systems, aerodynamic instabilities, meteorological conditions, and topographical variations, which can disturb the dynamic response and interior noise levels. These factors can be either correlated with or independent of each other. Excessive vibration levels of high-speed trains can lead to a series of problems related to ride comfort, train stability and track deterioration. Naturally, vibration and noise are interacted with each other, in which noise can be transmitted through air-borne and structure-borne paths to the interior of high-speed trains. The variation of noise levels is very sensitive as highspeed trains pass through various topographical terrains. Besides, aerodynamic noise becomes dominant as the speed of trains increases or trains travel through tunnels. Tracing the source that generates anomaly noise responses can give an important clue for monitoring operational safety and detecting adverse status. Pilot studies for the online monitoring of noise in the bogie of a high-speed train running on a railway in China have been conducted. The present study aims to investigate the relationship between ambient vibration induced by the rail-wheel interaction and noise measured from the bogie. The dynamic behaviour of high-speed trains is analysed in relation to the topographical variations (e.g., tunnels, viaducts, and plain area). Noise levels of the bogie are also investigated among various types of environmental conditions. Furthermore, the frequency response function is adopted to explore the correlation between the detected noise and ambient vibration using those on-board monitoring data.