Investigation Of Wave Propagation Of Rail Waveguides

With the development of social economy,the railway has become an important mode of transportation for people to travel with its advantages of economy and speed.As an important part of the railway,the railroad tracks bears a vital responsibility for the safe operation of the railway.The existing rail inspection vehicles have slow detection speed and low efficiency.With the increasing expansion of the railway system,the detection methods of the inspection vehicles are gradually difficult to meet the large and frequent inspection requirements.Therefore,ultrasonic guided wave detection technology with long propagation distance and wide detection range has received more and more attention.However,the effective implementation of this technology must rely on the understanding of the guided wave propagation characteristics.Based on this,this paper proposes a method to analyze the dispersion characteristics and wave structure of the guided waves in the rail,and simulate the guided wave defect detection through finite element simulation.The main contents are as follows:(1)The SIGA dispersion equation based on semi-analytical geometric analysis method is proposed to calculate the guided wave dispersion curve.The dispersion curve and wave structure in rails are abtained by this method.The energy distribution of the first four modes and other main modes in the rail is analyzed.Based on this,the appropriate excitation mode and frequency are selected.(2)Using the finite element software ABAQUS to establish a three-dimensional finite element model,simulate the propagation of guided waves in the rail,simulate different wave modes according to the wave structure analysis of each mode,and calculate the speed of the mode by the distance and time difference of the signal.The relative error of the group velocity calculated by the geometric analysis method is within 5%;and the main mode of the guided wave at 20 KHZ is simulated,and the defect detection is performed based on this,and the defect location and the real position are successfully performed.The relative error is 1.05%.The feasibility and accuracy of finite element simulation are verified.(3)Based on the updated Lagrangian increment theory,the SA-SIGA dispersion equation of the prestressed waveguide structure is derived,and the influence of different strain rates on the guided wave dispersion in the rail is analyzed.(4)For the energy leakage problem of guided wave propagation in open waveguides,in order to calculate the leakage mode of guided waves in the rail,a perfect matching layer technique is introduced,combined with the isogeometric analysis method to give the dispersion equation of PML-SIGA.Solve the leakage mode and propagation mode of the guided wave in the rail on the half space,and provide reference for the application of guided wave detection technology.