CN114674928A - Method for suppressing blind area in ultrasonic TOFD (time of flight diffraction) detection of thin plate structure based on second-order mode wave - Google Patents
Method for suppressing blind area in ultrasonic TOFD (time of flight diffraction) detection of thin plate structure based on second-order mode wave Download PDFInfo
- Publication number
- CN114674928A CN114674928A CN202210276438.7A CN202210276438A CN114674928A CN 114674928 A CN114674928 A CN 114674928A CN 202210276438 A CN202210276438 A CN 202210276438A CN 114674928 A CN114674928 A CN 114674928A
- Authority
- CN
- China
- Prior art keywords
- wave
- tofd
- detection
- alpha
- thin plate
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
Images
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N29/00—Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
- G01N29/04—Analysing solids
- G01N29/06—Visualisation of the interior, e.g. acoustic microscopy
- G01N29/0654—Imaging
- G01N29/069—Defect imaging, localisation and sizing using, e.g. time of flight diffraction [TOFD], synthetic aperture focusing technique [SAFT], Amplituden-Laufzeit-Ortskurven [ALOK] technique
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N29/00—Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
- G01N29/44—Processing the detected response signal, e.g. electronic circuits specially adapted therefor
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2291/00—Indexing codes associated with group G01N29/00
- G01N2291/02—Indexing codes associated with the analysed material
- G01N2291/023—Solids
- G01N2291/0234—Metals, e.g. steel
Landscapes
- Physics & Mathematics (AREA)
- Biochemistry (AREA)
- Health & Medical Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Chemical & Material Sciences (AREA)
- Analytical Chemistry (AREA)
- General Health & Medical Sciences (AREA)
- General Physics & Mathematics (AREA)
- Immunology (AREA)
- Pathology (AREA)
- Acoustics & Sound (AREA)
- Engineering & Computer Science (AREA)
- Signal Processing (AREA)
- Investigating Or Analyzing Materials By The Use Of Ultrasonic Waves (AREA)
Abstract
The invention provides a method for inhibiting a blind area in a sheet structure ultrasonic TOFD detection based on second-order mode waves, and belongs to the technical field of nondestructive detection. The method adopts a TOFD detection system consisting of an ultrasonic flaw detector, a TOFD probe, an organic glass inclined wedge block and a scanning device, and performs B scanning and signal acquisition along the surface of a thin plate workpiece to be detected to obtain A scanning signal sets at different scanning positions. And solving the positions of the second-order mode wave shortest propagation sound and the interface emergent point at different scanning positions by utilizing the Fermat theorem, the Snell's law and the wave mode conversion principle, and further determining the depths of the wafer receiving point and the defect endpoint in the blind area by combining with a simulated annealing algorithm. Compared with the existing alternative TOFD technology, the method can effectively inhibit the detection blind area of the thin plate structure and realize the depth quantification of the near-surface defects, and has higher engineering application value.
Description
Technical Field
The invention relates to a method for inhibiting a blind area of a sheet structure ultrasonic TOFD detection based on second-order mode waves, and belongs to the technical field of nondestructive detection.
Background
The Time of Flight Diffraction (TOFD) is a nondestructive testing method for quantifying defects by utilizing the Time difference of Diffraction longitudinal waves of end points of the defects, has the advantages of high quantification precision, high detection rate of area type defects and the like, and is widely applied to the detection of welding structures in the fields of petrochemical industry, nuclear power and the like. However, when the TOFD detection is performed on the near-surface defect, due to the fact that the ultrasonic pulse has a certain width, the diffraction wave at the end point of the defect is easy to annihilate in the through wave, a near-surface detection blind zone is formed, and the depth of the defect is difficult to quantify.
To solve the above problems, researchers have proposed mode-converted waves (JIN S J, et al. quantitative detection of small surface defects by using mode-converted waves in time-of-thin differential detection [ J ]. Journal of non-destructive evaluation.2020,39(2):33), secondary reflected longitudinal waves (CHI D Z, et al. thin reflected longitudinal wave on ultrasonic TOFD [ J ]. Journal of non-destructive Evaluation,2013,32(2): 164), semispan mode waves (Kingjie et al. semispan bottom surface defect TOFD detection [ J ]. aeronautical report, 2023,44(2):426674), the principle is that other forms of defect endpoint diffraction/scattering waves are adopted to replace direct diffraction waves used by the conventional TOFD, and aliasing with direct waves is avoided by increasing the propagation sound path. However, as the thickness of the structure to be detected is reduced, the propagation sound of these diffracted/scattered waves is close to the sound of the reflected longitudinal wave or the reflected transverse wave from the bottom surface of the workpiece to be detected, and the two are coupled to cause a reduction in the applicability of the method. The invention provides a method for inhibiting a blind area of a thin plate structure by ultrasonic TOFD detection based on second-order mode waves, which aims to reduce the range of the blind area of the thin plate structure and realize near-surface defect quantification.
Disclosure of Invention
The invention provides a method for suppressing a blind area in a sheet structure ultrasonic TOFD detection based on second-order mode waves. Aiming at the problem that the existing TOFD technology can be replaced to limit the near-surface blind zone suppression of a thin plate structure, the diffraction wave propagation time is prolonged by utilizing the wave mode conversion principle, and the detection blind zone suppression is realized. And (3) considering the variation of sound propagation time in the wedge block, correcting the sound time calculation error caused by wave mode conversion by combining Snell's law and Fermat's theorem, deducing the quantitative relation between the sound propagation time and the path of the second-order mode wave of the defect end point, and introducing a simulated annealing algorithm to realize near-surface defect depth inversion.
The technical scheme adopted by the invention is as follows:
a method for suppressing the blind area of ultrasonic TOFD detection of a sheet structure based on second-order mode waves is characterized in that a TOFD detection system consisting of an ultrasonic flaw detector, a TOFD probe, an inclined organic glass wedge block and a scanning device is adopted, B scanning and signal acquisition are carried out along the surface of a sheet workpiece to be detected, and an A scanning signal set is obtained. And determining coordinates of each point of the probe wafer according to the size information of the probe and the wedge block, solving the positions of the shortest propagation sound and the interface emergent point of the second-order mode wave at different scanning positions by utilizing the Fermat's theorem, the Snell's law and the wave mode conversion principle, and further determining the depths of the wafer receiving point and the defect endpoint in the blind area by combining with a simulated annealing algorithm. The method comprises the following steps:
(a) TOFD assay parameter determination
Determining TOFD detection parameters including TOFD probe frequency, wedge angle, probe center distance, detection gain, sampling frequency and scanning stepping according to the material, the geometric dimension and the detection range of the thin plate workpiece to be detected;
(b) a-scan signal set acquisition
Controlling a TOFD probe to perform B scanning along the surface of a thin plate workpiece by adopting the TOFD detection parameters determined in the step (a), wherein the scanning step length is delta S, the stepping times are N-1, and a data set formed by N scanning signals A is obtained in total;
(c) detection coordinate system establishment
Establishing a coordinate system by taking the surface of a thin plate workpiece to be detected as an X axis, the scanning direction as an X axis forward direction and the depth direction of the workpiece as a Y axis forward direction, and setting the projection position of the left end point of the transmitting probe wafer on the surface of the workpiece when scanning starts as a coordinate origin;
(d) second order modal wave propagation time calculation
The second-order mode wave is a received signal after primary bottom surface reflection and primary defect endpoint wave mode conversion in the transmission process of the excitation signal; since the front and rear wave modes reflected by the bottom surface are excited longitudinal waves, the propagation time of the second-order mode wave is divided into the time t before diffraction1And time after diffraction t2(ii) a Setting the center distance of the emission probe to be 2S and the longitudinal wave sound velocity inside the thin plate workpiece to be detected to be C LTransverse wave sound velocity of CSThe longitudinal wave sound velocity inside the wedge block is CWAnd default sound beam is generated from the midpoint of the transmitting probe to be vertical to the probe surface; reading the through wave arrival time t at the defect-free position of the thin plate workpiece to be detectedLWThe propagation distance q of the excitation longitudinal wave in the transmitting probe wedge block is obtained by the formula (1):
setting the diameter of the transmitting probe wafer as D, the angle of the matching wedge block as alpha, obtaining the coordinates of a sound beam transmitting point as (Dcos alpha/2, -qcos alpha), and the coordinates of a sound beam incident point at the interface of the wedge block and the thin plate workpiece to be detected as (Dcos alpha/2 + qsin alpha, 0);
setting the thickness of a thin plate workpiece to be detected as h, the depth of a defect end point to be detected as d, the horizontal distance from the defect end point to the midpoint of the two probes as an eccentric distance x, and setting x as a positive number when the defect is on the right side of the midpoint; setting the coordinates of the defect endpoint as (S + Dcos alpha/2 + qsin alpha + x, d); t is obtained from the formula (2) according to Snell's law1：
After diffraction by defectThe transverse wave interface exit point of the generated wave mode conversion deviates from the theoretical value, and the refraction angle change in the receiving wedge block causes the sound beam end point to be no longer the middle point of the wafer; discretizing the receiving wedge interface and the receiving probe wafer into array points, and setting k and l as the transverse wave interface emergent point and the acoustic beam end point abscissa respectively, wherein k is more than or equal to S + Dcos alpha/2 + qsina and is less than or equal to k is more than or equal to 2S + Dcos alpha 0+2 qsina 1, and 2S + (D-q) cos alpha 2+2qsin alpha is more than or equal to l is less than or equal to 2S + Dcos alpha +2 qsina; further, obtaining the coordinates (k,0) of the emergent point of the actual sound beam of the interface, wherein the coordinates of each point of the receiving probe wafer are (l, - [ qcos α + Dsin α/2+ (2S + Dcos α +2qsin α -l) tan α ]) Then t is obtained from the formula (3)2：
At this time, the order t is solved by using Fermat's theorem2The shortest k value, which satisfies:
the shortest propagation time t of the second-order mode wave is expressed by the formula (5);
(e) TOFD detection dead zone defect endpoint depth quantification
During actual TOFD detection, the second-order mode wave propagation time t and the eccentricity x can be read from a B scanning image, and the defect endpoint depth d and the acoustic beam endpoint abscissa l are unknown; let formula (5) be t ═ f (d, l); d is more than or equal to 0 and less than or equal to m which is the depth of the blind area because d is positioned in the TOFD detection blind area; discretizing the values of d and l, and setting the numbers of elements as 0,1,2, … i, … j and …; searching an optimal solution which minimizes | f (d, l) -t | in a value interval of d and l by using a simulated annealing algorithm; let D (0) ═ 0, l (0) ═ 2S + (D-q) cos α +2qsin α; in equation (6), it is determined whether or not to agree to use the new solution f (d (i), l (j)) as the next solution based on the probability P
And repeating the processes continuously until a global optimal solution is obtained by inversion, wherein the defect endpoint depth d (i) at the moment is the defect endpoint depth d to be detected.
The invention has the beneficial effects that: the method for inhibiting the ultrasonic TOFD detection blind area of the thin plate structure based on the second-order mode wave fully considers the time variation of the propagation sound inside the wedge block, and can effectively inhibit the range of the ultrasonic TOFD detection blind area of the thin plate structure. When the existing detection thin plate structure capable of replacing the TOFD technology is limited in use due to interference of bottom surface reflected longitudinal waves or reflected transverse waves, the method can realize near-surface defect depth quantification and has high engineering application value.
Drawings
FIG. 1 is a schematic diagram of a TOFD detection system employed in the present invention.
FIG. 2 is a drawing of an aluminum alloy sheet test block for machining an open groove on the bottom surface.
Figure 3 is an original TOFD-B scan.
Fig. 4 is the a-scan signal at eccentricity x-14.0 mm.
Fig. 5 is a through wave a scan signal without a defect.
Detailed Description
The following further describes a specific embodiment of the present invention with reference to the drawings and technical solutions.
A sheet structure ultrasonic TOFD detection blind area suppression method based on second-order mode waves adopts an ultrasonic detection system as shown in figure 1, wherein the ultrasonic detection system comprises an ultrasonic flaw detector, a pair of TOFD probes, a pair of longitudinal wave angle wedges, a scanning device and the like. The specific detection and processing steps are as follows:
(a) the test object is an aluminum alloy sheet test block as shown in FIG. 2, the thickness h is 10.0mm, and the longitudinal wave sound velocity C of the materialL6370m/s, shear wave speed CS3160m/s, wedge longitudinal wave speed CW2680 m/s. And (3) processing a bottom surface open groove on the test block, wherein the end point depth d of the bottom surface open groove is 2.5 mm.
(b) Detection was performed using a TOFD probe at a nominal frequency of 10 MHz. The main detection parameters include: the longitudinal wave wedge angle alpha is 60 degrees, the probe wafer diameter D is 8.0mm, the probe center distance 2S is 40.0mm, the sampling frequency is 340MHz, the detection gain is 60dB, the scanning step delta S is 0.5mm, and the start position of the A scanning time window is set before the through wave reaches the receiving probe. Under the detection parameters, the theoretical depth of the TOFD detection blind zone is calculated to be about 5.1 mm.
(c) B scanning the open slot on the bottom surface in the aluminum alloy sheet test block by using the detection parameters determined in the step (B) by using a TOFD probe to obtain 51A scanning signals, and exporting the signals in a txt file form through an A/D converter of a flaw detector. Fig. 3 shows a corresponding B-scan image, and it is obvious that the bottom-surface open-slot end-point diffracted waves are aliased with the through waves, and other defect end-point diffracted/scattered waves which can be used in place of the TOFD technique are aliased with the bottom-surface reflected waves to different degrees. At this time, the a-scan signal at x of 14.0mm is directly extracted from the original image, and as shown in fig. 4, the second-order mode wave propagation sound time t of 13.54 μ s is read. Since the second order mode wave has a relatively weak amplitude compared with the bottom surface reflected wave, the bottom surface reflected wave is well beyond the full screen in order to definitely read the second order mode wave.
(d) Reading through-wave propagation time t at defect-free interferenceLW12.25 mus, as shown in figure 5. And calculating to obtain the distance q between the center of the transmitting probe wafer and the theoretical emergent point of the interface, which is 8.0 mm. When the above known conditions are substituted into the formulae (3) and (4), k is 42.08 mm; further, when d is 2.66mm and l is 45.88mm, the absolute value of the difference between t and f (d, l) is the smallest, as calculated by the formulas (5) and (6). Therefore, the inversion value of the depth d of the bottom open groove end point is 2.66mm, and the absolute error is 0.16 mm. Obviously, the method can restrain the TOFD detection blind zone range of the thin plate structure from 5.1mm to within 2.5mm, and the relative error of the defect depth quantification does not exceed 6.4%.
Claims (1)
1. A method for suppressing a blind area in a sheet structure ultrasonic TOFD detection based on second-order mode waves is characterized by comprising the following steps:
(a) TOFD assay parameter determination
Determining TOFD detection parameters including TOFD probe frequency, wedge angle, probe center distance, detection gain, sampling frequency and scanning stepping according to the material, the geometric dimension and the detection range of the thin plate workpiece to be detected;
(b) a-scan signal set acquisition
Controlling a TOFD probe to perform B scanning along the surface of the thin plate workpiece by adopting the TOFD detection parameters determined in the step (a), wherein the scanning step length is delta S, the stepping times are N-1, and a data set consisting of N scanning signals A is obtained;
(c) detection coordinate system establishment
Establishing a coordinate system by taking the surface of a thin plate workpiece to be detected as an X axis, the scanning direction as an X axis forward direction and the depth direction of the workpiece as a Y axis forward direction, and setting the projection position of the left end point of the transmitting probe wafer on the surface of the workpiece when scanning starts as a coordinate origin;
(d) second order mode wave propagation time calculation
The second-order mode wave is a received signal after primary bottom surface reflection and primary defect endpoint wave mode conversion in the transmission process of the excitation signal; since the front and rear wave modes reflected by the bottom surface are excited longitudinal waves, the propagation time of the second-order mode wave is divided into the time t before diffraction 1And time after diffraction t2(ii) a Setting the center distance of the emission probe to be 2S and the longitudinal wave sound velocity in the thin plate workpiece to be detected to be CLTransverse wave sound velocity of CSThe longitudinal wave velocity inside the wedge is CWAnd default sound beam is generated from the midpoint of the transmitting probe to be vertical to the probe surface; reading through wave arrival time t at defect-free position of thin plate workpiece to be detectedLWThe propagation distance q of the excitation longitudinal wave in the transmitting probe wedge is obtained by the following formula (1):
setting the diameter of a transmitting probe wafer as D, the angle of a matched wedge block as alpha, obtaining the coordinates of a sound beam transmitting point as (Dcos alpha/2, -qcos alpha), and the coordinates of a sound beam incident point at the interface of the wedge block and the thin plate workpiece to be detected as (Dcos alpha/2 + qsina, 0);
setting the thickness of the thin plate workpiece to be detected as h, the depth of the defect end point to be detected as d, and the horizontal distance from the defect end point to the midpoint of the two probes as eccentricityDistance x, which specifies that x is a positive number when the defect is to the right of the midpoint; setting the coordinates of the defect endpoint as (S + Dcos alpha/2 + qsin alpha + x, d); t is obtained from the formula (2) according to Snell's law1：
The exit point of the transverse wave interface subjected to wave mode conversion after defect diffraction deviates from a theoretical value, and the refraction angle change in the receiving wedge block causes that the sound beam end point is no longer the middle point of the wafer; discretizing the receiving wedge interface and the receiving probe wafer into array points, and setting k and l as the transverse wave interface emergent point and the acoustic beam end point abscissa respectively, wherein k is more than or equal to S + Dcos alpha/2 + qsina and is less than or equal to k is more than or equal to 2S + Dcos alpha 0+2 qsina 1, and 2S + (D-q) cos alpha 2+2qsin alpha is more than or equal to l is less than or equal to 2S + Dcos alpha +2 qsina; further, obtaining the coordinates (k,0) of the emergent point of the actual sound beam of the interface, wherein the coordinates of each point of the receiving probe wafer are (l, - [ qcos α + Dsin α/2+ (2S + Dcos α +2qsin α -l) tan α ]) Then t is obtained from the formula (3)2：
At this time, the order t is solved by Fermat's theorem2The shortest k value, which satisfies:
the shortest propagation time t of the second-order mode wave is expressed by the formula (5);
(e) TOFD endpoint depth quantification of defects in blind zones
During actual TOFD detection, the second-order mode wave propagation time t and the eccentricity x can be read from a B scanning image, and the defect endpoint depth d and the acoustic beam endpoint abscissa l are unknown; let formula (5) be t ═ f (d, l); d is more than or equal to 0 and less than or equal to m which is the depth of the blind area because d is positioned in the TOFD detection blind area; discretizing the values of d and l, and setting the numbers of elements as 0,1,2, … i, … j and …; searching an optimal solution which minimizes | f (d, l) -t | in a value interval of d and l by using a simulated annealing algorithm; let D (0) ═ 0, l (0) ═ 2S + (D-q) cos α +2qsin α; in equation (6), it is determined whether or not to agree to use the new solution f (d (i), l (j)) as the next solution based on the probability P
And repeating the processes continuously until a global optimal solution is obtained by inversion, wherein the defect endpoint depth d (i) at the moment is the defect endpoint depth d to be detected.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210276438.7A CN114674928A (en) | 2022-03-21 | 2022-03-21 | Method for suppressing blind area in ultrasonic TOFD (time of flight diffraction) detection of thin plate structure based on second-order mode wave |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210276438.7A CN114674928A (en) | 2022-03-21 | 2022-03-21 | Method for suppressing blind area in ultrasonic TOFD (time of flight diffraction) detection of thin plate structure based on second-order mode wave |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN114674928A true CN114674928A (en) | 2022-06-28 |
Family
ID=82074962
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202210276438.7A Pending CN114674928A (en) | 2022-03-21 | 2022-03-21 | Method for suppressing blind area in ultrasonic TOFD (time of flight diffraction) detection of thin plate structure based on second-order mode wave |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN114674928A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115047079A (en) * | 2022-08-17 | 2022-09-13 | 南通友联数码技术开发有限公司 | Ultrasonic phased array rapid focusing method for multilayer composite board |
| CN116460366A (en) * | 2023-06-01 | 2023-07-21 | 中国机械总院集团江苏分院有限公司 | Ultrasonic cutting machine and ultrasonic processing technology using same |
-
2022
- 2022-03-21 CN CN202210276438.7A patent/CN114674928A/en active Pending
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115047079A (en) * | 2022-08-17 | 2022-09-13 | 南通友联数码技术开发有限公司 | Ultrasonic phased array rapid focusing method for multilayer composite board |
| CN116460366A (en) * | 2023-06-01 | 2023-07-21 | 中国机械总院集团江苏分院有限公司 | Ultrasonic cutting machine and ultrasonic processing technology using same |
| CN116460366B (en) * | 2023-06-01 | 2023-08-29 | 中国机械总院集团江苏分院有限公司 | Ultrasonic cutting machine and ultrasonic processing technology using same |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN114674928A (en) | Method for suppressing blind area in ultrasonic TOFD (time of flight diffraction) detection of thin plate structure based on second-order mode wave | |
| EP1927856B1 (en) | Ultrasonic inspection method | |
| US8578580B2 (en) | Quality control method and manufacturing method for pipe | |
| JP4166222B2 (en) | Ultrasonic flaw detection method and apparatus | |
| CN110082428B (en) | Method for measuring elastic constant of material based on combination of crack tip effect and laser ultrasound | |
| CN112098526B (en) | Near-surface defect feature extraction method for additive product based on laser ultrasonic technology | |
| WO2022151530A1 (en) | System for detecting multiple materials by using longitudinal critically refracted waves based on single-angle wedge block and method for measuring sound velocity thereof | |
| CN110243945B (en) | Ultrasonic TOFD blind area suppression method based on synthetic aperture focusing and mode converted wave | |
| CN108896660A (en) | A kind of hexagonal crystal material near surface tiny flaw detection method based on shear wave back scattering | |
| CN107356670A (en) | A kind of ultrasonic phase array weld defect detection method based on oblique incidence | |
| CN108802191B (en) | Water immersion ultrasonic flaw detection method for rolled steel defects | |
| Fei et al. | Simultaneous velocity, thickness and profile imaging by ultrasonic scan | |
| CN105806947A (en) | Ultrasonic detection method for detecting tilting defect | |
| Jin et al. | Corrected Mode-Converted Wave Method for Detecting Defects in TOFD Dead Zone | |
| EP3985388A1 (en) | Ultrasound flaw detection method, ultrasound flaw detection device, manufacturing equipment line for steel material, manufacturing method for steel material, and quality assurance method for steel material | |
| JP2000146921A (en) | Method and device for ultrasonic crack detection | |
| US4596142A (en) | Ultrasonic resonance for detecting changes in elastic properties | |
| CN113720918B (en) | Method for measuring transverse wave sound velocity of material | |
| CN115639157A (en) | Surface wave-based surface crack position, length and angle measurement method | |
| CN114047256A (en) | Ultrasonic imaging method for defects of flat ceramic membrane based on dynamic array element synthetic aperture focusing | |
| Blouin et al. | SAFT data processing applied to laser-ultrasonic inspection | |
| CN116660388A (en) | Alternative TOFD technique selection method | |
| Shijie et al. | TOFD detection of shallow subsurface defects in aluminum alloy thin plates by half-skip mode-converted wave | |
| JP2943567B2 (en) | Pipe shape inspection device | |
| Margetan et al. | Ultrasonic signal attenuation in engine titanium alloys |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination |