Research On SFEM And Its Application In Simulation For High Speed Train Sound Field

The special structure of high speed train leads to the confined space in the train,which keeps interior sound pressure at a stable value.Therefore,high speed train sound pressure is directly related to the ride comfort of passengers.At the same time,the sound pressure is too large will cause damage to human organs,and even endanger the safety of life.In the simulation analysis of high speed train sound field,finite element method has the influence of dispersion error due to the "over-stiff" characteristic,which affects the calculation precision.The smooth finite element method can solve this problem.In this paper,the application of smoothed finite element method in high-speed train sound field simulation has done the following work:(1)Based on the theory of smoothed finite element method,the acoustic analysis procedure is clarified and the influence of different smoothing methods on the accuracy is discussed.The possibility of using smoothed finite element method in two-dimensional acoustic applications is studied by means of numerical examples.On the basis of maintaining the "lower limit solution" characteristic of finite element method,smoothed finite element method can still maintain high and stable calculation accuracy under the distorted grid.(2)The process of simulation and analysis of the three-dimensional smooth finite element method is clarified.Based on smoothed finite element method,the theoretical model is programmed and the application of smoothed finite element method in the field of three-dimensional acoustics is further studied.Compared with finite element method,smoothed finite element mothed can obtain higher calculation accuracy;meanwhile,its calculation accuracy fluctuates little with the change of the average grid size.(3)Taking CRH380B high speed train as a prototype,an analysis model of high speed train sound field is established.The sound field simulation is carried out based on smoothed finite element method,and the response characteristics of high speed train sound field is clarified.By comparing the simulation data with the experimental data,the validity of smoothed finite element method for simulating high speed train sound field is verified.(4)Based on smoothed finite element method,the variable density method of high speed train sound field simulation is researched,which saves the computational cost and improves the calculation precision.Through the method,the changes of high speed train sound field under three operating conditions are studied,and the influence of different speeds on the air density and sound pressure in the train is clarified.The conclusion was drawn as follows:When the train meeting in the open air or crossing the tunnel,the sound pressure increase linearly with the speed.The sound pressure inside the train is fluctuating with the speed due to the great change of sound speed during trains meet in the tunnel.