Research On Interior Noise Prediction And Control Technologyof High Speed Train

The interior noise is a substantial increase with the speed of the high-speed train increasing.It becomes a key technology in the design of high-speed train to research and develop the noise control technology and also reflects the strength of the high-speed train technology.It is a system engineering to do noise control.If the low-noise train is not designed and noise prediction is not done at the beginning,it will lead to high costs,affect the production schedule and vehicle performance while do some measures to control noise after noise issues exposure.Therefore,noise prediction and control technology researching is important to shorten the design cycle,reduce costs and ensure the vehicle.To improve the noise performance of trains and meet the needs of research and development,this paper studies interior noise prediction and control technology of high-speed train speeding 350km/h.The structure of High-speed train,a typical system of the medium frequency's noise and vibration,is complicated.If the FE-BEM method is adopted completely,simulation analysis will produce a large number of grids in the high frequency and increase the difficulty of computing and extend the design cycle.But Statistical Energy Analysis(SEA)method is suitable for high frequency,which including lots of modal and is limited in low frequency.Therefore,this paper proposes a hybrid analysis(FE-SEA)method to create hybrid FE-SEA prediction model of high-speed train.For the beam structures,which have large stiffness and low modal density,for example,smaller traction beam,bolster,side beams and so on,and divided into FE subsystems.The larger body profile,interior panels,glass windows and other large area construction are divided into SEA subsystems.The SEA cavities will be created between inside and outside body structures.Also the passenger compartment will be divided into SEA cavities.Then each subsystem is assigned corresponding equivalent material properties.Such a model,not only retains the full impact on the accuracy of the structure,but also is made necessary simplification,thus ensuring the noise prediction accuracy,and improves the speed of the simulation.The body structure of High-speed train is hollow aluminum extrusion and many interior panels are honeycomb panels and corrugated sheets,which cannot be directed,modeled in SEA subsystem.To solve this problem,we propose an equivalent method based on dynamics and acoustic theory.According the equivalent method,the body structure is simplified by three composite structure,we called "equivalent board",which have the same total thickness,the same areal density.And the top and bottom skins material and thickness are the same as the original structure.In addition,the intermediate rib structure is equivalent to a kind of "virtual material".Based on the same dynamic characteristics before and after equivalent,it is calculated to obtain parameters of equivalent "virtual material" material.According to these parameters,the equivalent three-layer composite board structure is established and puts forward the high frequency equivalent plate failure frequency estimation method.Parameters such as external excitation loads and damping loss factor between structures have a vital effect on the accuracy of prediction results.Parameters of high-speed train interior noise prediction model can be acquired by experiment and calculation.Modal density and coupling loss factor of each subsystem can be calculated.A method using plate and cavity coupling theory is proposed to test the structural loss factor to solve the problem of the acoustic radiation damping is repeated in the simulation calculation.Then the structural loss factor of body profiles,trim and other complex components are measured using this method.The simulation results of the high speed train are carried out,and the prediction results of the interior noise are obtained.Compared with the experimental results,the spectrum curves are basically the same,which can meet the needs of engineering application.Based on the statistical energy analysis theory,a panel contribution analysis method based on power flow is proposed,and the contribution of interior panel noise radiated to the interior noise energy is studied by using the noise prediction results.According to the noise simulation analysis,from the point of view of engineering application,the sound insulation optimization and the application of sound-absorbing seat are studied.Sound insulation performance of car body section is mainly influenced by parameters such as total thickness,thickness of plates,angle of ribs,and thickness of ribs and so on.Optimization project can be raised by studying relation of above-mentioned parameters and transmission loss.Thus,we improve transmission loss by 3dB on the premise of a few added weights.Performance of sound absorption seats has a great influence on interior sound field.A project is proposed by studying the influence of putting additional sound absorption structures on seats,under seats or on the back.Line test results show that SPL can be decreased by 1.5dB through using this project.In this article,hybrid FE-SEA method is used in the prediction of high-speed vehicle interior noise simulation.It can solve equivalent of composite structures and acquire model parameters.Therefore,we can get a more accurate result and quicker calculation speed,which meets the need in engineering and has a significant meaning on R&D and designing of high speed trains.In addition,noise decreased structures proposed in this test-such as acoustic optimization sections and sound absorption seats-provide a design method and solution for interior noise control,which have a high value on engineering.