Research Of Railway Track Flaw Detection Device Based On Virtual Instrument

In this paper,combined with the development status of railway track flaw detection equipment in China,and according to the functional requirements of the investigation site,a virtual instrument-based railway track flaw detection device is designed and applied to railway track flaw detection by using ultrasonic flaw detection technology.Firstly,the characteristics of ultrasonic wave and its propagation are studied to understand the causes of attenuation of ultrasonic wave in the process of flaw detection.Through careful analysis of the process of rail ultrasonic flaw detection,the reflection,transmission and waveform conversion laws of vertical and oblique incidence of ultrasonic wave on heterogeneous interface are explored,combined with the practical application background of the system,the structure of the mechanical support,the structure of the flaw detection wheel,the spray coupling mechanism and the guide wheel of the railway track flaw detection device are analyzed and designed by using the modular design method,and the mechanical structure of the flaw detection device is modeled in three dimensions,then the vibration law of the flaw detection device under the occasional excitation source and periodic excitation source is analyzed by the simplified model of the flaw detection wheel,and the method of reducing the vibration is discussed to improve the stability and accuracy of the flaw detection system.The signal acquisition system of the flaw detection device is the primary work to realize the railway track ultrasonic flaw detection.This paper then completes the design of signal acquisition hardware system of flaw detection device and the construction of signal acquisition software platform.Hardware design includes signal source,ultrasonic transducer,data acquisition card selection and signal conditioning circuit design of signal acquisition system of flaw detection device;The software of the signal acquisition system is to use LabVIEW software which is flexible and can change the software program at any time to build the signal acquisition control panel of the ultrasonic track flaw detection system,so as to realize the acquisition,storage and display of the ultrasonic track flaw detection signal and other signals.Finally,the method of extracting defect information from the received flaw detection echo signal is studied.A digital bandpass FIR filter is designed by using window function method to eliminate the interference of high and low frequency signals independent of defect information in the flaw detection echo signal,the the filtered signal is converted from time domain to frequency domain by fast Fourier transform to accurately identify the missing fillings.The echo signal of rail flaw detection is simulated by MATLAB and the parameters of FIR filter are obtained.The signal processing software of rail flaw detection devicedeveloped in LabVIEW is tested,in order to obtain reliable method of defect information extraction of railway track ultrasonic flaw detection signal.