Investigation And Prediction On High-speed Train Coupling Excitations And Interior Vibration And Sound Characteristics

An improved energy finite element method was proposed and a complete high-vehicle "vehicle-seat-human" coupling dynamics model was established.In order to predict high-speed train interior sound field and vibration comfort,the research was carried out including wheel-rail noise sources prediction,aerodynamic noise sources prediction,interior full-spectrum noise prediction,and ride vibration comfort prediction.Firstly,based on the rigid-flexible coupling theory,vehicle-rail and rigid-flexible coupling dynamic models considering the flexible characteristics of wheel and rail were established.The effects of track irregularities and flexible characteristics of wheel and rail on the wheel-rail contact force were studied.Based on the time domain boundary element method,the time-domain prediction models of wheel-rail noise were established,and the influence of flexible features on wheel-rail vibration and radiation noise were also studied.Under Sato track irregularity,the wheel-rail contact force in the middle-high frequency bands and peak responses of vibration and radiating noise in the wheel-rail system were more significant.In the middle-high frequency bands,the dynamic responses in the wheel-rail system were more significant when considering the wheel-rail flexible characteristics.The secondary suspension force of the carriage and wheel-rail noise responses at the target cabin surfaces were obtained and taken as the wheel-rail excitation source boundary conditions for subsequently predicting interior noise and dynamic characteristics of the cabin.Secondly,a complete coupling dynamics model of high-speed train,seat system and human body was established to predict the cabin vibration responses and vibration comfort under the wheel-rail excitations obtained bofore.The seats close to the side wall and bogie areas had poorer vibration comfort.The seat comfort deteriorated as the seat stiffness increased in general.When the damping was pretty small,the seat comfort becomed better with the cushion damping increasing.When the damping was pretty large,the seat comfort deteriorated as the damping increased.As the suspension stiffness increased,the seat comfort becomed better at first and then deteriorated.When the damping was pretty small,increasing suspension damping could improve ride comfort inside the cabin.And the ride comfort deteriorated as the suspension damper increased when the suspension damping was pretty large.As the train speed increased,the vibration comfort inside the cabin near bogie area deteriorated rapidly.Thirdly,the aerodynamic noise characteristics around the high-speed train windshield area,aerodynamic noise sources of high-speed train groups and component contributions were studied based on the nonlinear acoustic theory.The results indicated that the aerodynamic noise in the windshield region was similar to the cavity noise in the low frequency range,while it was broadband noise in the middle and high frequency bands.And the aerodynamic noise energy was proportional to the velocity of the 5th power.The sound pressure leve peaks of the bottom longitudinal distribution appeared in bogie area,and the peaks of top longitudinal distribution appeared in the rear aera of pantograph fairing.The aerodynamic noise sources in the tail region dominated the acoustic energy contribution to the far-field observations.The aerodynamic noise sources in the front bogie area at carriage surface dominated the acoustic energy contribution in the most frequency bands.The aerodynamic noise responses at target carriage surfaces were obtained as the excitation source boundary conditions for the subsequent interior noise prediction.Finally,the sound insulation effect was introduced to the existing energy finite element analysis(EFEA)theory,and the external sound excitation energy transmission path was changed accordingly.Therefore,EFEA could be applied in full-spectrum interior noise prediction in complex structures,such as high-speed trains.A complete high-speed train interior noise prediction model was established based on EFEA.And the parameters of each carriage system were obtained through experiments and simulations.The excitation sources mentioned above were applied to the models and full-specturm interior noise were predicted and verified.The cloud map of interior noise distribution characteristics was also obtained.Furthermore,the acoustic energy contribution of exterior excitation sources were inwestigated based on the EFEA interior noise prediction model,and the prediction and optimization of interior sound quality parameters were also conducted.The external acoustic excitation sources dominated the energy contribution to the interior noise in the high frequency range,and the contribution of the mechanical excitations and acoustic excitations was basically close in the middle-low frequency bands.The energy contribution of aerodynamic noise was mainly concentrated in the low frequency bands,and the acoustic contribution of wheel-rail noise was mainly concentrated in the high frequency bands.The contribution of rail noise in the frequency band below 1250 Hz was much larger than that of wheel noise.As frequency bands increased,the contribution of wheel-rail noise gradually approached.The noise excitations in bogie area affected the noise in high frequency bands at both ends of the carriage.The wheel-rail noise excitations were optimized and had a significant effect on the interior noise in high frequency bands,and the optimization effect of the acoustic comfort parameters inside the carriage could be perceived by the human ear.