Damage Identification Of Metro Vehicle Wheels Based On Lamb Wave

In recent years,with the increase of urban traffic pressure,the metro vehicle has gradually occupied an important position in urban transportation.During the service period of metro vehicle vehicles,the impact of foreign objects,brake disc impact heat,and rail wear are easy to cause wheel damage,resulting in train operation failure,which is dangerous to people's lives and property.At present,the wheel inspection is mainly carried out by regular wheel drop inspection,which is time-consuming and laborious,and there is a greater risk potential during the inspection cycle.Lamb waves have the advantage of being sensitive to damage,and there is no need to remove paint and dismantle the structure during the maintenance process.Therefore,this paper proposes a Lamb wave-based damage detection method for wheel damage,to identify and locate the damage.The main work is as follows in the thesis:(1)The dispersion characteristics of Lamb waves are studied,and the dispersion curves of Lamb waves are drawn by MATLAB to provide a theoretical basis for the effective use of Lamb waves for structural damage detection.On this basis,the excitation mode of the Lamb wave is studied.The excitation mode,excitation frequency,number of peaks,and sensors of the Lamb wave signal are optimized and analyzed.The selection of various parameters of the excitation signal of the steel plate and the wheel is determined through experiments.(2)The finite element simulation analysis method of the wheel based on COMSOL is studied,and the finite element simulation model of Lamb wave propagating in the wheel is constructed.The Lamb wave propagation group velocity and phase velocity in the simulation model are compared with the modal velocity in the dispersion curve.The simulation is consistent with the theoretical value,and the effectiveness of the wheel model is verified.Finite element simulation of damage defects is carried out on the surface of the wheel model.The effect of Lamb waves on different damage defects is studied.It is proved that A0 and S0 modal waves have different effects when encountering different types of damage,and the correlation between the degree of damage defect and the amplitude of the response signal is verified.(3)A damage identification index based on signal energy is proposed.Hilbert-Huang transform signal processing technology is introduced,and the signal damage characteristic parameters are obtained through the time-frequency analysis method,and then the damage degree identification index is obtained.A damage recognition method based on a support vector machine is introduced.The change law of damage degree and signal amplitude is determined,which is based on the energy amplitude of the damage reflected wave as the damage identification quantity.(4)A damage identification and location algorithm based on HHT is proposed.This method performs Hilbert-Huang transform on the response signals when the Lamb wave propagates before and after wheel damage.By analyzing the instantaneous amplitude spectrum of each path signal,the peak time of the signal energy before and after the damage is obtained,and then the time delay parameter is obtained.Combining various parameters with the ellipse positioning algorithm and hyperbolic positioning algorithm,the wheel damage location is achieved.Finally,a wheel damage detection experiment is carried out,and the location and size of the damage are estimated through the analysis of the experimental damage signal.