Transfer Path Analysis And Control Of Floor Vibration Based On OTPA Method

With the rapid development of high speed railway,noise problem has drawn great attentions.Field tests have shown that bogies are still the most important sources of interior noise and vibrations for high speed trains.This work first collected the vibration data of the floor over bogies and those at other key positions,and then employed the Operational Transfer Path Analysis(OTPA)method to develop a two-level transfer path analysis model in bogie area.In consideration of the transfer function of the second suspension,suggestions are proposed to reduce the floor vibrations above bogies,building basis and reference for feasible counter measures.This thesis mainly analyzes the transfer path of the floor vibrations above bogies and the counter measures,and is composed of the following contents.(1)A literature review is first given regarding floor vibrations of high speed trains and the transfer path.It is concluded that OPTA is suitable for analyses of the floor vibrations of the high-speed trains in China.(2)The experimental study of the floor vibrations above bogies of high-speed trains in our country was carried out.According to the result of sound source identification determines of interior noise,the floor above the bogie is the main source.The vibration characteristic of floor and other structure under it was studied.Thus,the transfer path of the floor vibration is clear.(3)Following the principles of OTPA,functions of the transfer paths and contributions of different paths are derived in theory.The floor above the bogie is chosen as the research target,the connection position of car body and bogie frame corresponding to secondary suspension element is chosen as the excitation source.A two-level transfer path analysis model in bogie area and the corresponding calculation code is developed.(4)Based on the deveploed transfer path model,main paths with significant contributions to the floor vibrations are sorted based on their values.A transfer function is determined for the second suspension.This transfer function is further analyzed in consideration of the contribution of the second suspension to the floor vibrations,from which suggestions are proposed to improve the second suspension and reduce the floor vibrations above bogies.