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Engineering Applications of Ultrasonic Time-Of-Flight Diffraction

About: The article was published on 1989-08-01 and is currently open access. It has received 154 citations till now. The article focuses on the topics: Time-of-flight diffraction ultrasonics & Ultrasonic sensor.
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Journal ArticleDOI
TL;DR: In this paper, a PPM EMAT generated shear horizontal (SH) wave was used to inspect Austenitic welds and all defects were identified from every side of the weld/plate using the SH waves.
Abstract: Austenitic welds are inspected using PPM EMAT generated shear horizontal (SH) waves. Results are compared to measurements taken using a 1D piezoelectric phased array using the total focusing method (TFM). For the first time there is clear experimental evidence of the SH wave method demonstrating higher sensitivity to defect detection. SH waves suffer less beam steering in a weld than either compression or SV waves, which can miss defects due to weld microstructure anisotropy and attenuation. All defects were identified from every side of the weld/plate using the SH waves, but this was not possible using the piezoelectric transducer.

74 citations


Cites methods from "Engineering Applications of Ultraso..."

  • ...Time of flight diffraction (TOFD) is an ultrasound technique developed for the NDT of nuclear power plants [5–7], and it has been used for general weld inspection [4]....

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Journal ArticleDOI
TL;DR: In this article, the authors present a review of SAFT and TOFD with reference to representative examples from the past and the present, as well as a quantitative evaluation of crack sizes.
Abstract: The detection of defects in materials and components using ultrasonic nondestructive testing and evaluation techniques is of interest in many industrial areas. Reliable defect detection requires defined and reproducible scanning of the probes along the surface of the components. For post-processing of the recorded rf-data the Synthetic Aperture Focusing Technique SAFT has been successfully applied to improve the performance of ultrasonic testing. For specific defect and component configurations, the Time-of-Flight Diffraction technique TOFD has also been successfully applied for quantitative evaluation of crack sizes. This contribution reviews developments and applications of SAFT and TOFD with reference to representative examples from the past and the present.

60 citations

Journal ArticleDOI
01 Jun 2003-Insight
TL;DR: In this article, an experimental study for evaluation of TOFD technique for determination of size of the surface breaking cracks was conducted. But difficulty was experienced using TOFD to size defects extending less than about 2mm depth, due to the presence of the lateral wave which obscures the tip-diffracted signals from the defects close to the surface and also due to inherent lack of time resolution near the surface.
Abstract: This paper deals with an experimental study for evaluation of TOFD technique for determination of size of the surface breaking cracks. The study was confined to simulated cracks. The steel test blocks used for the study contained 0.5mm wide vertical slits of various heights ranging from 0.91mm to 30mm. Another set of blocks contained inclined slits (10°, 15°) inclination of various heights ranging from 2.56mm to 19.82mm. Both the vertical and inclined slits were opened to the top surface. TOFD equipment Model MICROPLUS of M/S AEA Technology, UK with manual scanner along with longitudinal angle beam probes of 45° - 4MHz were used for the study. The blocks were scanned along the slits / defects and across the slits. The scanned images were analysed for the sizing. The results of the study indicated an average error of ±0.13 for depth in vertical slits and ±0.05 for inclined slits whereas the average error in length measured was ±0.36mm for vertical slits and ±0.29mm for inclined slits. However difficulty was experienced using TOFD to size defects extending less than about 2mm depth. This is due to the presence of the lateral wave, which obscures the tip-diffracted signals from the defects close to the surface and also due to the inherent lack of time resolution near the surface.

54 citations

Journal ArticleDOI
TL;DR: In this paper, a model-based method for ultrasonic echo parameter estimation is proposed, where the ultrasonic signal is assumed to be composed of an unknown number of Gaussian echoes corrupted by white Gaussian noise.

53 citations

Journal ArticleDOI
TL;DR: Higher order wavelets are used for analyzing the de-noising performance for TOFD signals obtained from Austenitic Stainless Steel welds and it is observed that higher orderWavelet Transform based thresholding techniques have been applied largely for de- noising of ultrasonic signals.

47 citations