Time-of-flight diffraction ultrasonics

About: Time-of-flight diffraction ultrasonics is a research topic. Over the lifetime, 544 publications have been published within this topic receiving 3189 citations.

TOFD near surface dead zone defect locating detection method based on wave-type transformation

Abstract: The invention discloses a TOFD near surface dead zone defect locating detection method based on wave-type transformation and belongs to the field of nondestructive detection. The method includes that an ultrasonic detection system comprising a TOFD ultrasonic detector, a detection probe, a calibration block and scanning device is adopted for TOFD detection; longitudinal waves emitted by the TOFD probe diffract when encountering defects, and when an incident angle reaches a supercritical value, wave-type transformation of longitudinal wave to transverse wave or transverse wave to longitudinal wave occurs; a defect end point solution model is built according to geometrical relationship among sonic path distances of waves different in type in a scanning image B; a projection distance d' of shortest sonic path distance of transformed waves in the vertical direction and a projection distance S in the horizontal direction between an intersection point of the transformed waves and a shortest sonic path distance position are measured, and then a distance d between a defect end point and a detection face can be calculated by combining the projection distance d' and the projection distance S with a probe central distance 2S, longitudinal wave sonic speed C1 and transverse wave sonic speed Cs through a formula to realize locating of near surface dead zone defects. By the method, original A scanning signals do not need to be extracted for analysis and post-processing; the method is high in operability and high in engineering application value.

Method for evaluating life of metallic material

Abstract: PROBLEM TO BE SOLVED: To provide a method by which the life of a metallic material can be evaluated easily. SOLUTION: This method is constituted to find the life consuming rate of a high-temperature pipeline 10 based on the correlation between the life consuming rate of the pipeline 10 found in advance from the number and density of creep voids of the pipeline 10 and the generating rates of A flaws (dense flaws) by finding the generating rate of the A flaws by the TOFD method.

Multiframe Ultrasonic TOFD Weld Inspection Imaging Based on Wavelet Transform and Image Registration

Abstract: TOFD (time of flight diffraction) is a kind of weld defect detection technology by using ultrasonic diffraction wave signal. Because the diffraction intensity is far less than ultrasonic echo wave intensity, thus, the noise contained in TOFD signal is fairly large, and the formed image is not clear enough. Therefore, it is difficult to determine the size of defects accurately. In this paper, a method of noise reduction of TOFD signal and improving the resolution of the image are discussed based on the combination of wavelet thresholding and image registration. Wavelet multiresolution analysis method is adopted and the A-scan signal is decomposed into different frequency components. We propose a new threshold function to process the wavelet coefficients, which guarantees to denoise while preserving the useful information as much as possible. Setting up the ultrasonic TOFD inspection system and the image data with randomly distributed noise can be obtained via fine shake of the probes during testing. Then, image registration based on maximum correlation and blending is adopted to eliminate the noise in further step. The result shows that the proposed method can achieve denoising, together with resolution enhancement.

TOFD (Time of Flight Diffraction) detection method for butt weld defects of steel structures and middle-thick-walled tubes of power station

Abstract: The invention discloses a TOFD (Time of Flight Diffraction) detection method for butt weld defects of steel structures and middle-thick-walled tubes of a power station. The detection method comprises the steps of: adopting a group of defect reference blocks, and producing defects, which common occur in actual but welded joints, such as cracks, incomplete fusion, incomplete penetration, slag inclusion and pore defect samples, on the defect reference blocks; detecting the defect blocks by using a TOFD detection method, and thereby obtaining TOFD detection maps of the defect blocks; detecting the actual welded joint by using the TOFD detection method, comparing the TOFD detection map in the actual welded joint with the TOFD detection maps of the defect blocks respectively to determine whether the actual welded joint is qualified; through scanning the manual defect blocks, and analyzing and comparing the maps, deficiencies and the TOFD standard blocks are compensated, and reliability and accuracy in nature and quantity determination of defects in the TOFD detection method are further increased.

Laser ultrasonic TOFD method

Abstract: We applied laser ultrasound for the time of flight diffraction (TOFD) measurement. To find an effective testing condition of TOFD method, laser ultrasonic transmission around the slit in glass specimens was observed using the photoelastic ultrasonic visualization system. After the observation we constructed the laser TOFD system and applied to the slit depth measurement of aluminum plate, and then, obtained highly accurate results.