The Research On The Pipe Ultrasonic Guided Wave Detection System Construction And Signal Processing Method

Pipe ultrasonic guided wave testing technology has some advantages that are fast,economic, reliability and without stripping outsourcing layer etc。It is a front developmentdirection on the pipe defects detection Ultrasonic guided wave signal processing ability isdirectly related to identify the defects and estimate the position of the defects. So it is needa signal processing method that can filter out or weaken the other modal signal. In thepaper, through the ultrasonic guided wave frequency dispersion equation is researched, thefrequency dispersion curve of the calculation is obtained. According to the calculation，thedetection of need the frequency interval and speed is found out. First ultrasonic guidedwave detection system is constructed, and then the data of the test is collected andanalyzed, finally the signal processing research. The research content and results are asfollows:1) Based on the theory of ultrasonic wave guide, it is studied that the ultrasonic waveguide of frequency dispersion equation and frequency dispersion curve of solution.Through put forward disassembling coordinate system of the frequency demonstrates-phase velocity with the grid extension points method. The frequency dispersion curve ofthe algorithm is obtained and the test the frequency dispersion curve is drawn.2) Constructed ultrasonic guided wave detection system and collected. The need ofguided wave signal data3) Wavelet transform could filter out the clutter in the signal; the defect location erroris0.65%about the pipeline of4%defects. Put forward two methods that are basis on thelance distance method and angle cosine method, combining sliding window method andsuperposition principle. The two methods can filter out other modal single and clutter, thedefect location is about0.6%.on the pipeline of4%defects. In the composite methods, theangle cosine and wavelet transform method is a better method, it can filter out other modaland clutter, defect location is about0.5%. Draw envelope curve and attenuation curve;distinguish between at the end of the echo and flaw echoes.4) Complete software design with the software of MATLAB.