Study on the application of transfer path analysis to interior noise and vibration of railway vehicles

Abstract

The interior noise characteristics of railway vehicles vary depending on the position of the cabin. In general, interior noises are louder in the area directly above bogies (ends of the cabin) than in the center of the cabin. It has been known that structure-borne sounds from bogies contribute greatly to the interior noises directly above bogies. This paper describes, using measured data obtained with the rolling stock test plant at Railway Technical Research Institute (RTRI), the application of the operational transfer path analysis (OTPA) to determine the contribution ratio of each transmission path of vibration from bogies to cabin floors. It is considered that structure-borne sounds from bogies propagate mainly through the parts connecting the bogie and car body such as single-link-type traction devices (traction links), yaw dampers, and air springs. As a result of applying the OTPA and determining the contribution ratios, it has been confirmed that the contribution ratios varied depending on the position of the floor and the frequency band. In addition, the validity of the contribution has been verified by examining the linearity of input/output data and the correlations of input data using multiple coherence functions and partial coherence functions. Although a bogie vibrates rigidly in the low frequency range with the very high correlation between the vibrations of the bogie and the parts connecting the bogie and car body, the correlation becomes low in the high frequency region. Therefore, it is expected that the contribution of each transfer path can be well estimated by applying the OTPA in the high frequency range for structure-borne sounds from bogies.

Keywords

• interior noise
• railway vehicle
• structure-borne sound
• transfer path analysis
• contribution ratio