Research On Elastic Wave Propagation Characteristics Of Track Structure Based On Wave Finite Element Method

As an important infrastructure and a key component of the transportation system,railway industry has developed rapidly in recent years.The high-speed rail has shortened the distance between cities and promoted the economic growth of our country.It has become one of our country's business cards.The subway has greatly eased the traffic congestion in the city,facilitated the travel of citizens,and promoted the economic growth of the city.With the rapid development of railways,various engineering and technical problems have also followed,such as damage to the track structure,excessive vibration and noise.In fact,various problems in the track structure can be attributed to the result of elastic wave propagation.Analyzing the propagation behavior of elastic waves in the track structure will help us understand and solve such problems in a deeper way.There have been some researches on the wave propagation behavior of the infinite periodic track structure at home and abroad,but generally the relevant studies are few.It is even rare to study the wave behavior of the track structure by bandgap mechanism and the researches basically stay at the stage of plane beam model.The coupling effect of three-dimensional model and the influence of rail section deformation cannot be considered.Therefore,this paper has carried out the research of elastic wave propagation characteristics in track structure from the perspective of elastic wave bandgap.The main work of this paper is as follows:(1)Based on the wave finite element method,the formula for calculating the dispersion curve and dynamic response is deduced,the dispersion curve of the plane track model and the three-dimensional track model are analyzed,the difference of the dispersion curve of different models is explored.The energy distribution,the coupling and conversion of the waveform are also analyzed.(2)The formula of calculating the dispersion curve of the track structure by the wave superposition method is deduced,and the feasibility of the wave superposition method is verified through numerical experiments.The factors that cause the deviation of the dispersion curve are analyzed.According to the acceleration of the track structure measured on site,the dispersion curve of the track structure is calculated.(3)The wave finite element method was used to explore the dynamic response of the plane and three-dimensional track structure,and the influence of factors such as track structure stiffness,damping,and sleeper spacing on the rail displacement and ground reaction force was analyzed.The displacement of track structure at different distances is calculated and the correlation between distance and response is studied.(4)The power flow of the three-dimensional track structure is analyzed by the wave finite element method,and the structural bandgap can be obtained very quickly.The power flow difference between the three-dimensional structure and the plane structure is compared,and the reasons and influencing factors of the bandgap reduction of the three-dimensional track structure are analyzed.(5)Combining the bandgap characteristics of phononic crystals and the low-frequency multi-mode characteristics of acoustic black hole structures,a new type of phononic crystal vibration isolator is proposed.The wave finite element method is used to analyze the bandgap behavior of the vibration isolator,and finally a train-floating slab track-tunnel coupling dynamics model is established to compare the performance of the new phononic crystal vibration isolator and the steel spring vibration isolator.