Theorical Analysis And Control Studies In Wheel/Rail Noises Of High Speed Railway

High-speed railway has been widely developed all over the world. In China, high-speed railway development is certainly the inevitable choice for modern railway. It is a key study which is currently conducted to develop the track of vibration-reduction and noise-reduction enabling itself to adapt the conditions of different environments and different operating, under the background of how to ensure safety, stability and dynamic regularity of the track. Therefore, it is necessary for high-speed railway noise pollution problems to carry out for more comprehensive and more detailed theoretical researches.Environment noise pollution in high-speed railway will limit the further increase of train speed. Wheel/rail noise generated by high-speed train is a very important noise source. Detailed research on wheel-rail noise generation mechanism and control technology is one of the tasks in the process of developing high-speed railway.Structure admittance and sound radiation efficiency of wheel-rail system are very important basic problems to predict wheel/rail noise. Structure admittances of wheel/rail system are analyzed by the FEM (Finite Element Method) in the present paper. Then, using the BEM (Boundary Element Method), sound radiation efficiencies of the wheel/rail system structure are investigated. The work will provide some bases for predicting accurately wheel/rail noise.The work in this dissertation focuses on wheel/rail noise radiation in high-speed railway. From the vehicle-track dynamic interaction, based on the vehicle-track coupled dynamics theory and acoustics radiation theory, a model is proposed to predict wheel/rail noise in high speed railway. Numerical simulation method is used to investigate the wheel/rail noise generation mechanism, radiation characteristics, propagation and control technology in high-speed railway. Some reasonable suggestions are put forward for the low-noise design of the wheel-rail system structure. Theory references are provided for our newly-line design, environmental impact assessment and environmental management of high-speed railway.The present model has comprehensive consideration of the various parts of the vehicle-track coupled vibration interaction. The contributions of radial and axial vibration of wheel, vertical and lateral vibration of rail to the wheel/rail noise are taken into account in this model. Wheel/rail rolling noise and wheel/rail impact noise can be predicted, and the vibration and noise radiation of ballasted track and ballastless track structure can be also analyzed in the present model. Low-noise design on wheel/rail system in high speed railway is investigated in this model.Using computer language FORTRAN95, a prediction and analysis system of wheel/rail noise-WRNOISE (Wheel/Rail Noise), is developed. Compared with the existing wheel/rail noise prediction model TWINS, STTIN and test data, this model is verified to be effective.Theoretical analysis on wheel/rail impact noise and rolling noise generated by high speed train running on ballastless track section are carried out with software WRNOISE. The mechanisms of wheel/rail impact noise generated by the wheel flats, rail weld joints are proved. Frequency spectrum characteristics, time-history properties, sound propagation of wheel/rail rolling noise due to wheel and rail surface roughness are revealed.In order to maximize the reduction of wheel/rail noise, low-noise idea should be used to guide the planning, design and construction of high-speed wheel/rail system. The affecting factor of wheel/rail noise is not simply one, but rather a result of a combination of factors. Using the numerical simulation approach, the low-noise factors of the wheel/rail system structures are revealed in this thesis.The technology of sound absorption and obstructing noise are two common ways to reduce noise pollution in high speed railway. Using model WRNOISE, the effects of reduction-noise of sound-absorbing panel are analyzed, and the influences of material parameters of porous sound-absorbing panel on the reduction of wheel/rail noise are proved in this paper. The BEM is used to analyze in detail the influence of sound barrier structure itself, source frequencies, installation location and absorption materials on noise-reduction. These results will provide useful reference for engineering design.