Using OTPA Method To Analyse Transfer Paths In A High-speed Train Body For Interior Noise

In recent years,as the significant progresses in the high-speed railway construction has been made in China,the demands of passengers for the riding comfort are getting higher and higher.As a method improved by traditional TPA(Transfer Path Analysis),the OTPA(Operational Transfer Path Analysis)method overcomes the shortcomings of the traditional method.With a high efficiency,it can be carried out during the working condition of the targeted machine.This method is gradually applied in the field of rail traffic and provides the theoretical basis and guidance for the noise control of the train.Firstly,according to the basic principle of OTPA,the author compiles computing program via Matlab.To simulate the actual vibration and noise response and validate the application performance of the OTPA method,the virtual sound-vibration system is formed by an analytic calculation approach.Secondly,the operational test data of the vibration and noise of the train is analyzed synthetically,which is prepared for the selection of calculation conditions and the establishment of transfer path model in OTPA analysis.The OTPA analysis consists of two aspects: discussion of the influence factor on the interior noise and exterior noise source,such as the running direction,the pantograph state,the traction structure and the running speed;and qualitative analysis of the relationship between the interior noise and the vibration of the vehicle parts,such as the internal plate,the bogie structure,the base of pantograph and so on.Finally,with the interior noise standard point at the pantograph end of the TP03 carriage regarded as the target point,the OTPA transfer path analysis model is established from the aspects of "path reference point-target point" and "sound source reference point-target point".As for the mechanism of the noise transmission path,an assumption is made that the direct sound propagation is ignored,and the symmetric sound source and the symmetric path are merged.Based on the operational test data and the OTPA method,combined with the results of spherical array sound source identification,the path contribution and sound source contribution of the interior noise are analyzed respectively from aspects of the total value and spectrum.The results show that the OTPA analysis corresponds to the calculation results of the spherical array sound source identification.At low speed,the contribution of the floor path and the contribution of the bogie sources is dominant.When the speed is greater than 300km/h,the contribution of the roof path and pantograph source are dominant.The noise from the exterior sources of the vehicle transfer into the interior mainly through the form of structural excitation,and the contribution of air excitation is non-significant.In the 160~315Hz frequency bands of interior noise,the contribution of the traction rod's vibration is significant.At the 250 Hz frequency band,the contribution of pantograph base's vibration is the largest.At the 630 Hz frequency band,the contribution of anti-rolling torsion bar's vibration is the largest.