Prediction Method And Influencing Factors Of Wheel/Rail Sound In Small Radius Curve Section Of Metro

Urban rail is one of the most common modes of travel in the current urban development,but with the continuous improvement of people’s requirements and the continuous innovation of subway technology,the accompanying noise problems have become increasingly prominent.Curved wheel-rail noise includes rolling noise,impact noise and howling,among which howling is mainly caused by wheel self-excited vibration and rim friction.In this paper,the howling caused by self-excited vibration of wheels is studied,and the howling in small radius section of subway is judged by complex eigenvalue analysis,and the wheel-rail sound of small radius curve is calculated by transient model.The results are as follows:1.in the wheel-rail noise test of the curve section with small radius,the vibration acceleration of the inner rail in the section with a radius of 350 m was tested,and it was found that the vibration increased sharply at 80 Hz,350Hz and 630 Hz.The main frequencies of corresponding noise are 630 Hz,2500Hz and 4500 Hz,that is,they increase greatly at630 Hz,2500Hz and 4500 Hz.The main noise source at 630 Hz is rail.The main noise source at 2500 Hz and 4500 Hz is the wheel with high grade,which is the howling.2.In the curve section with a radius of 350 m supported by the monolithic track bed,the complex eigenvalue analysis predicts that friction self-excited vibration may occur at300.4Hz,626.4Hz,2458.2Hz and 4425.3Hz respectively,among which the equivalent damping ratio corresponding to 2458.2Hz is the smallest,and the probability of howling is the largest.The higher the speed,the easier it is to produce howling.With the constant increase of friction coefficient,the absolute value of equivalent damping ratio also increases,indicating that the probability of unstable vibration increases,and the smaller the radius,the easier it is to produce howling.When the radius is greater than 550 m,there is almost no noise surge and no curve howling.3.The difference between the simulated value and the experimental value in the main frequency band of wheel-rail noise calculated by the three-dimensional instantaneous rolling model is small,and the main frequency is 2000～2500Hz.At the same time,it is verified that friction self-excited vibration occurs at 300.4Hz,626.4Hz,2458.2Hz,and 4425.3Hz in the frequency band where howling occurs,and the numerical simulation predicts that noise surges at 630 Hz and 2500 Hz,indicating that howling occurs here,and the maximum noise at2458.2Hz corresponds to the most likely occurrence here predicted by the previous paper.Speed has little influence on the size of howling,but it has a great influence on the generation of howling;With the decrease of friction coefficient,the noise of curved wheel-rail decreases gradually.Radius has a great influence on the size and generation of howling.