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Study on the Origin of Rail Corrugation at a Long Downhill Braking Section Based on Friction-Excited Oscillation

Abstract This article studies a special rail corrugation phenomenon occurring at a braking section of Shenzhen Metro Line 3 based on friction-excited oscillation. The rail corrugation is strongly related to the braking operation: when the braking operation was canceled, the corrugation did not appear again after being ground. In this article, a new viewpoint that the corrugation originates from the unstable vibration of the wheel–rail–brake shoe braking system is put forward. To test this point of view, a finite element model composed of two wheelsets with a brake shoe braking system and two rails for complex modal analysis was established. Parameter sensitivity analysis was carried out to develop some measures to suppress rail corrugation. The results show that rail corrugation at the long downhill braking section originates from the unstable vibration at about 430 Hz of the wheel–rail–brake shoe braking system. The corrugation wavelength predicted by the finite model is about 55 mm, which shows good agreement with the on-site data. The results of parameter sensitivity analysis show that the influence of the coverage angle of the brake shoe on the rail corrugation is significant. The possibility of the rail corrugation and its progression speed increase significantly with a decrease in the coverage angle of the brake shoe. To suppress the rail corrugation, the coverage angle should not be less than 48° when designing the brake shoe structure. The influence of the installation position of the brake shoe on the rail corrugation is also obvious. The position of the brake shoe with a pressure angle of 8° can restrain rail corrugation to the greatest extent. The contact state between the brake shoe and wheel tread has little influence on rail corrugation. In practice, the brake shoe should be in full contact with the tread.