Study On Vibro-acoustic Characteristics Of Low Frequency Noise Reduction Trim Panel Of High Speed Train Based On The Locally Resonant Mechanism

Vibration and noise are the core issues that restrict the green,environmental,and sustainable development of high-speed railway.Among them,the interior noise of high-speed train affects the riding comfort which is a key indicator of vehicle design,development,and stable operation.The traditional measures of vibration and noise reduction can effectively control mid-high frequency interior noise,but have little effect on low-frequency noise control.On the one hand,it is because conventional sound insulation and sound-absorbing materials mainly exhibit high-frequency noise reduction characteristics.Due to reducing the weight of an entire vehicle.It is difficult to improve low-frequency noise reduction performance.With the increase of train’s operation speed,the high-speed turbulence excitation acted on the train body becomes significant,and the energy of low-frequency structural vibration and sound source excitation are also increasing,which causes the problem of low-frequency noise in the car to become serious.Therefore,this thesis aims to reduce the low-frequency vibration and noise of high-speed train body panel.A gyroscopic phononic crystal panel is designed and constructed based on the principle of local co-displacement response.The band gap characteristics,vibration and sound radiation and sound insulation characteristics of the gyroscopic phononic crystal plate are studied,and then the noise reduction effect of the highspeed train body’s interior panel is analyzed.The main content and conclusions of this work are as:1.Based on the line test,the noise characteristics of high-speed trains are tested and analyzed,and the relationship between vibration and sound radiation of panels in key areas of a car body and noise inside the car is studied.Considering the influence factors of the band gap,the effects of structure parameters and material parameters of the key parts of gyroscopic phononic crystal plates on band-gap characteristics are investigated in depth,and their characteristics are optimized.2.Using finite element,a model of gyroscopic phononic crystal cells is established,and its band structure diagram is obtained.Based on the principle of local resonances of phononic crystals and structural vibration modes,the band-gap formation mechanism of gyroscopic phononic crystals is systematically analyzed.Considering the influential factors of band gaps,the influence of changing structural parameters and material parameters of key parts of the gyro-type phononic crystal plates on the band-gap characteristics is deeply investigated,and the band-gap characteristics are optimized.The results show that the formation of band gaps depends on the effect of local resonance mode of the gyro resonator on the substrate plate,and the mutual coupling between the motion of substrate plates and local resonance units is the cause of the band gap,and a reasonable selection of cell parameters can effectively optimize the band-gap characteristics.3.A prediction model of vibration,sound radiation and sound insulation of the gyroscopic phononic crystal plate is established.Based on comparison of the vibro-acoustic characteristics of the same size base plate,the vibration,sound radiation and sound insulation of phononic crystal plates to the base plate in the low-frequency band gap range is studied.The influence of the loads’ number,the size of periodic arrangement and constraints on the vibration,sound radiation and sound insulation characteristics are systematically explored.4.The composite structure of trim panels with gyroscopic phononic crystals is established.Based on the comparison of acoustic,vibration characteristics with the ordinary interior panel of the same size,the vibro-acoustic characteristics of trim panels composite structure with the gyroscopic phononic crystal are investigated.The influence of the thickness and damping of the trim panel on the acoustic and vibration characteristics of the interior panel composite structure are separately investigated.The results show that in the low-frequency range,the combined structure of the phononic crystal interior trim panel has a better effect on the vibration and noise reduction compared with an ordinary one.Increasing the thickness and damping of interior panels can improve the vibration and noise characteristics of interior panels to a certain extent,especially the valley value of sound insulation characteristic curve can be increased at the same time.