Near-surface defect recognition method based on ultrasonic TOFD

A defect identification, near-surface technology, applied in the field of surface and near-surface defect identification, can solve the problems of insensitivity, time-consuming, damage to near-surface defect signals, etc., to achieve the effect of simple detection process and short time-consuming

CN101839895AInactive Publication Date: 2010-09-22HARBIN INST OF TECH
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Patent Information

Authority / Receiving Office
CN · China
Current Assignee / Owner
Publication Date
2010-09-22
Estimated Expiration
Not applicable · inactive patent

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Abstract

The invention relates to a near-surface defect recognition method based on ultrasonic TOFD, belonging to the field of ultrasonic nondestructive detection. The invention solves the problems that the prior ultrasonic TOFD detection technology is not sensitive to surface and near-surface defects, auxiliary detection devices are required by the existing hardware technology, the data processing process through the existing software technology is complex, the time is long, the suppression to lateral waves is not full and the near-surface defect signals are damaged. The process of the method comprises selecting probe spacing according to the thickness of an object to be detected and the angle of probes to enable a longitudinal wave main axis acoustic beam transmitted by a transmitting probe to be received by another probe after the acoustic beam is propagated along a W-shaped acoustic path in the object to be detected. By adopting the selected probe spacing, A scanning is conducted to the object to be detected, D scanning and B scanning are conducted to the object to be detected according to the obtained A scanning signals to respectively obtain D scanning images and B scanning images, and thereby the defect recognition is realized and the length and the buried depth of the defects are obtained. The method can be widely used in the filed of ultrasonic nondestructive detection.
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Description

technical field

[0001] The invention relates to the field of ultrasonic non-destructive testing, in particular to an identification technology for surface and near-surface defects based on ultrasonic TOFD method. Background technique

[0002] Ultrasonic time-of-flight diffraction method, referred to as ultrasonic TOFD (Time of Flight Diffraction) method, is a non-destructive testing method based on receiving the diffraction signal at the end of the defect to locate and quantitatively measure the defect. It is suitable for the detection of large-thickness weld structural defects. At the same time, the ultrasonic TOFD method has the technical problem of being insensitive to near-surface defects and shallow surface opening defects. In order to solve this problem, academic paper 1: Zhang Rui et al., Ultrasonic Diffraction-Echo Transit Time Method In-Situ Quantitative Nondestructive Estimation of Weld Cracks, Chinese Journal of Mechanical Engineering, 2000, 36(5): 54~57, proposed...

Examples

specific Embodiment approach 1

[0017] Specific implementation mode one: combine figure 1 and figure 2 To illustrate this embodiment, a method for identifying near-surface defects based on ultrasonic TOFD described in this embodiment, its specific steps are:

[0018] Step 1: According to the thickness of the detected object and the refraction angle of the probe, adjust the distance between the transmitting probe 5 and the receiving probe 6, perform A-scan on the detected object, and obtain an A-scan signal;

[0019] Step 2: According to the A-scan signal obtained in Step 1, perform D-scan on the object to be detected to obtain a D-scan image;

[0020] Step 3: According to the A-scan signal obtained in Step 1, B-scan the object to be detected to obtain a B-scan image;

[0021] Step 4: According to the D-scan image obtained in step 2 and the B-scan image obtained in step 3, perform positioning measurement on the defect in the tested object, and obtain the length and burial depth of the defect in the detecte...

specific Embodiment approach 2

[0029] Specific implementation mode two: combination image 3 , Figure 4 and Figure 5 Describe this implementation mode, this implementation mode is a specific example of implementation mode 1:

[0030]In this embodiment, the artificial defect in the aluminum alloy plate is used as the detection object, the thickness of the aluminum alloy plate is 20.0 mm, the buried depth of the end of the artificial defect in the aluminum alloy plate is 2.92 mm, and the length of the artificial defect is It is a 15.0mm bottom open straight groove; the detection process is: the longitudinal wave refraction angle of the transmitting probe 5 and the receiving probe 6 in the aluminum alloy plate is 60°, and the distance between the transmitting probe 5 and the receiving probe 6 is adjusted to 110mm. Perform A-scan on the aluminum alloy plate to obtain the A-scan signal, see image 3 , according to the obtained A-scan signal, D-scan the aluminum alloy plate, mark the scanning center line on ...