Defect detecting method based on ultrasonic flaw detection

Abstract

The invention discloses a defect detecting method based on ultrasonic flaw detection. The method comprises the following steps: 1, acquiring an ultrasonic echo signal and uploading the ultrasonic echosignal synchronously; 2, determining wave crests and wave troughs; 3, eliminating extreme points; 4, dividing the signal: determining a time interval between every two adjacent extreme points, judging dividing points, determining sampling moments of the dividing points, judging signal division, sorting the dividing points and dividing the signal; 5, judging signal separation and performing signalseparation; and 6, identifying a defect. The method is simple in steps, reasonable in design, convenient to implement and good in using effect; the judgment of the dividing points and the determination of the sampling moments of the dividing points are achieved by performing threshold judgment on the time interval between every two adjacent extreme points, and the ultrasonic echo signal is divided; then signal separation judgment and signal separation are respectively performed on every divided signal, and independent ultrasonic echo signals at multiple defect positions in the same ultrasonicecho signal can be quickly and accurately identified.

Description

technical field [0001] The invention belongs to the technical field of ultrasonic flaw detection, and in particular relates to a defect detection method based on ultrasonic flaw detection. Background technique [0002] Ultrasonic flaw detection (also known as ultrasonic testing or ultrasonic testing) is a non-destructive testing method that uses the difference in acoustic properties of materials and their defects to reflect the reflection of ultrasonic wave propagation and the energy change of penetration time to test the internal defects of materials. The principle of ultrasonic flaw detection is that the transmission loss of ultrasonic waves in solids is very small, and the detection depth is large. Since ultrasonic waves will reflect and refract on heterogeneous interfaces, especially if they cannot pass through gas-solid interfaces, if there are pores, cracks, Defects such as delamination (gas in the defect) or inclusions, when the ultrasonic wave (also called ultrasonic...

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Problems solved by technology

[0008] In addition, when using the sparse decomposition method for signal denoising (also called signal extraction), the essence is to use the matching pursuit algorithm for signal extraction. Because in the matching pursuit algorithm, firstly, the selection of Gabor atoms has no physical meaning, and secondly, if If a wrong Gabor atom is selected in a certain iteration, the subsequent iteration process has to correct this error, resulting in mistracking and poor algorithm performance.

Moreover, according to the sparse signal representation theory, when the size of dictionary atoms is smaller than a threshold, due to the cumulative consistency constraints, the sparse representation is unstable and unreliable

Therefore, the existing sparse decomposition methods have many defects

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