Research Of Three Dimensional Inversion Methods Of Defects Within The Columnar Based On The Ultrasonic Detection

The columnar artifacts are widely used in aerospace, defense, ammunition, and otherfields. In the production process, it is easy to cause surface or internal defects, which caninfluence the final performance of the product. Therefore it needs to be tested to ensure thenormal use in the process of production or before use. In this paper, cylinder members aretreated as object of study. By using ultrasonic technology to research the defects echo signals’feature extraction technology and three-dimensional inversion method.In this paper, introduced the principle of the ultrasonic automatic testing for the plumeartifacts, acquired ultrasonic signal about standard artifacts, analyzed the characteristics ofecho signal and noise source in the process of the automatic detection, determined the signalprocessing program; HHT and wavelet transform were used respectively to feature extraction,the results show that both methods can effectively restrain noise and extract the defectcharacteristics, wavelet transform method is slightly higher SNR than HHT, but there is astrong relationship between the treatment effect and the selection of wavelet base.Deduced the method about the defect of inversion based on the Born approximation andthe transit time method, and inversion the hole shape defects in the standard test-piece inthree-dimensional, analyzes the advantages and disadvantages of two methods: Bornapproximation method is only effective for near central hole defects because of itsapproximation principle; Transit time method can be applied to three-dimensional inversionof all defects, but for nearly center hole defects, Born approximation is more effective.In practice, according to the test requirements and defects, choose corresponding featureextraction method and three-dimensional inversion method. For similar products in theultrasonic automatic testing, the paper’s research results have reference significance.