Study On Low Frequency Sound Insulation Performance Of Composite Floor Structure Of High Speed Train Based On Phonon Crystal

With the continuous improvement of high-speed trains operating speed,the sound environment in-train is seriously affected by the vibration and noise problems caused rail transit,reducing the ride comfort of passengers.Therefore,the sound insulation design of the train body structure for the train noise source(this paper mainly focuses on the bogie part)is crucial.The current sound insulation measures can effectively control the middle and high frequency noise in-train.However,the low frequency noise control needs to be further improved.The phonon crystal structure can form low frequency band gap under the action of local resonance,inhibiting the propagation of elastic wave and playing a role of low frequency sound insulation and noise reduction.Therefore,the phonon crystal is applied to the floor structure of high-speed trains,the low frequency noise in-train is effectively controlled and the sound environment in-train is improved.This paper is based on the phonon crystal correlation theory and finite element analysis,aiming at the problem of the low frequency noise control in high-speed trains,the application of the phonon crystal in the low frequency sound insulation of high-speed trains composite floor structure is studied,the band-gap characteristics of the phonon crystal structure and the influencing factors of band-gap characteristics are systematically analyzed,and the sound insulation characteristics of the phonon crystal structure and the influencing factors of sound insulation characteristics are analyzed.Based on the above research conclusions,appropriate materials and structures are selected,and a composite phonon crystal structure with better low-frequency sound insulation performance is designed.Combined with the floor structure of the bogie of high-speed train,the feasibility of the application of the composite phonon crystal structure in high-speed train is explored.Relevant research can provide some theoretical support for low frequency noise inside high-speed train.The research conclusions are as follows:(1)Analyzing the band gap characteristics of single-cell phonon crystal structure,the combined force formed by the scatterer motion and the long-wave traveling wave in the matrix is be coupled,so that the elastic wave cannot continue to propagate forward due to the localization of energy,which leads to the generation of the band gap,and thus the phonon crystal structure has good low-frequency band gap characteristics.The results show that the parameters(scatterer density,coating density and Young’s modulus)have a great influence on the low frequency band gap characteristics of the phonon crystal.The structure form of the phonon crystal is changed,which can realize the artificial design and regulation of low frequency band gap characteristics.(2)The analysis of the sound insulation characteristics of single-cell phonon crystal structure shows that the sound insulation characteristics are consistent with the band gap characteristics.Because of its special band gap characteristics that the elastic wave within the band gap cannot continue to propagate forward,the phonon crystal structure has good sound insulation characteristics within the band gap.Meanwhile,the structure form of the phonon crystal is changed to realize the artificial design and control of low frequency sound insulation performance,and has good flexibility in sound insulation design.(3)Based on the study of monocellular the phonon crystal structure,a composite the phonon crystal structure with four monocellular structures and open holes in the scatterer coating layer is established by keeping the lattice constant unchanged,and the performance of sound insulation is compared and analyzed.The results show that the composite phonon crystal structure has better sound insulation characteristics in low-frequency band than the unicellular structure,and also shows good sound insulation characteristics in other frequency bands,which is more in line with the noise source frequency band formed by high-speed trains.In addition,it is more suitable for the sound insulation design of high-speed trains.(4)Based on the existing floor structure of high-speed trains,the composite phonon crystal structure is applied to the floor structure,and the composite floor of the phonon crystal structure is established.The sound insulation characteristics of the whole structure are analyzed.The research results show that the sound insulation of the phonon crystal composite floor structure in low frequency band has been significantly improved comparison with that of the original composite floor structure,and the sound insulation of the whole frequency band has been greatly optimized comparison with that of the original floor structure.Therefore,the design can provide an idea for the low frequency acoustic environment control high speed trains.