Ultrasonic backscatter sizing using phased array – developments in tip diffraction flaw sizing

Jacques, F.; Moreau, F.; Ginzel, Ed

doi:10.1784/insi.45.11.724.52966

Cited by 18 publications

(6 citation statements)

References 4 publications

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“…To locate the crack tip and subsequently to measure the crack depth, a spherical wave front diffracted from the sharp crack tip was used. The application of the crack tip diffraction method, which is a type of backscatter sizing techniques for the size determination of internal flaws in the material, has been described in detail by Jacques et al 44 The principle of the application of the ultrasonic‐phased array technique for measuring the fatigue crack depth is schematically shown in Figure 3. The frequency and size of the linear‐phased array ultrasonic probe were 10 MHz and 4.96 mm × 5.00 mm, respectively.…”

Section: Materials and Experimental Proceduresmentioning

confidence: 99%

On the application of laser shock peening for retardation of surface fatigue cracks in laser beam‐welded AA6056

Kashaev

Ushmaev

Ventzke

et al. 2020

Fatigue Fract Eng Mat Struct

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The present study aims to investigate the extent to which the fatigue behaviour of laser beam-welded AA6056-T6 butt joints with an already existing crack can be improved through the application of laser shock peening. Ultrasonic testing was utilized for in situ (nondestructive) measurement of fatigue crack growth during the fatigue test. This procedure allowed the preparation of welded specimens with surface fatigue cracks with a depth of approximately 1.2 mm. The precracked specimens showed a 20% reduction in the fatigue limit compared with specimens without cracks in the as-welded condition. Through the application of laser shock peening on the surfaces of the precracked specimens, it was possible to recover the fatigue life to the level of the specimens tested in the as-welded condition. The results of this study show that laser shock peening is a very promising technique to recover the fatigue life of welded joints with surface cracks, which can be detected by nondestructive testing. K E Y W O R D Saluminium alloys, fatigue crack, laser beam welding, laser shock peening, residual stress, ultrasonic crack tip diffraction

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Section: Materials and Experimental Proceduresmentioning

confidence: 99%

On the application of laser shock peening for retardation of surface fatigue cracks in laser beam‐welded AA6056

Kashaev

Ushmaev

Ventzke

et al. 2020

Fatigue Fract Eng Mat Struct

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“…Ultrasonic PAUT technology and equipment continues to advance ( 6 ). For example, the latest PAUT equipment and technology uses data acquisition and processing methods similar to the historic synthetic aperture focusing techniques to provide higher resolution images of the flaws.…”

Section: Resultsmentioning

confidence: 99%

Implementation of American Association of State Highway and Transportation Officials/American Welding Society D1.5 Phased Array Ultrasonic Weld Inspection Programs

Azari

Kok

2022

Transportation Research Record: Journal of the Transportation R

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This paper describes highlights of phased array ultrasonic testing (PAUT) nondestructive evaluation (NDE) research activities at the Federal Highway Administration’s (FHWA’s) Advanced Sensing Technology (FAST) NDE Laboratory. The work supports the goal to implement ultrasonic techniques in lieu of radiographic techniques for American Association of State Highway and Transportation Officials (AASHTO)/American Welding Society (AWS) D1.5 Bridge Welding Codeinspection of full penetration bridge fabrication welds. The paper also describes some of the advantages and disadvantages of the process to implement a PAUT inspection program. The results of this study support the goal of broader implementation of ultrasonic testing (UT) with results to date showing a good correlation of the comparative inspection results between PAUT and radiography. There is, however, a need to develop a more comprehensive set of weld flaws to ensure a fully representative flaw set is evaluated. To support that goal, the FAST NDE Laboratory is currently using ultrasonic simulation software to 03611981221090236ement the test plate data with a virtual database of simulated flaws. A successful implementation of PAUT can result in a more efficient inspection process with detailed permanent records and images of the flaw locations mimicking the historic radiograph. As more bridge fabrications incorporate PAUT, there will be a broader PAUT experience base as the AWS committee, teamed with the bridge fabricators, FAST NDE Laboratory, and other contributors continue to work toward replacing all required radiography in AWS D1.5 with an option to use PAUT.

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“…TOFD techniques use forward scatter signal analysis. Limitations of TOFD as a result of flaw proximity to the test surfaces and ring time have been discussed elsewhere [4]. TOFD requires probe access from two sides of the flaw to facilitate the receiver probe optimising on the transmitted forward scattered pressures.…”

Section: Back Diffractionmentioning

confidence: 99%

A Complete Solution for Weld Inspections: Phased Arrays and Diffraction Sizing

Moles¹,

Labbe²

2007

Volume 9: Eighth International Conference on Creep and Fatigue at Elevated Temperatures

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Welds have been inspected by radiography for years, but this technology has major drawbacks: low detection rates for critical planar defects (i.e. cracks and lack of fusion), subjective interpretation, no vertical sizing capability, significant safety hazards, licensing issues, plant closures, and is generally slow. For decades, the main alternative was manual ultrasonics, which is also slow, subjective and normally has little hardcopy record. New technology and techniques are now available for improved weld inspections, specifically phased array technology and diffraction techniques. Phased arrays are essentially the industrial version of medical ultrasound, but require a very different approach. In contrast to medical activities, industrial applications typically require a correctly angled beam, with large quantities of data, on variable component geometry, and the ability to save and image defects. All this capability is now packaged in a portable unit, which can be used for rapid and reliable weld inspections. Specifically, the OmniScan MX can now perform a single linear scan of the weld, while the instrumentation performs multiple scans at different angles simultaneously. In addition, phased arrays can perform unique scans, like S-scans (sectorial scans), record and display all data in “top, side, end” views or similar, and perform multi-mode scans. Phased arrays permit electronic rastering in many different modes, which saves considerable inspection time; for example, some estimates show that phased arrays are five or more times quicker than manual scanning. Besides being portable and requiring just a single operator, portable phased arrays are now economically competitive with other weld inspection techniques — and generally provide a much better inspection. The “new” techniques consist of forward and backward diffraction for sizing defects. In reality, both these techniques have been around for years, but new technology has made them more practical. Forward diffraction (TOFD or Time-Of-Flight Diffraction) is now well established, and has been demonstrated for many applications. For most weld inspections, TOFD just requires a single linear pass, with two transducers (or arrays) on either side of the weld. TOFD provides good sizing and defect detection in the midwall, though it has dead zones at the two surfaces. Generally, sizing with TOFD is significantly better than with amplitude techniques, but is limited to defects ∼3 mm and up. TOFD also has the great advantage that it is highly independent of defect orientation, unlike pulse echo techniques. Even better, phased arrays can perform both pulse echo and TOFD simultaneously during a single linear scan, so giving essentially a “complete” weld inspection. Another diffraction sizing technique which has received relatively little attention until recently is “tip back diffraction”. This approach uses the low amplitude signals reflected back from crack tips to size defects. Back diffraction has the great advantages that it is intuitive, and can size defects as small as ∼1 mm, which is generally better than TOFD. However, tip back diffraction has the major disadvantage that it is sometimes difficult to correctly distinguish the crack tips from other signals, and signal-to-noise ratio is usually poor. These two limitations are largely overcome by phased arrays; first, the imaging allows correct determination of the crack tip, and second, new piezo-composite arrays with focusing and filtering give significantly improved signal amplitudes. S-scan imaging can be performed with off-the-shelf phased array equipment. Some of the more advanced phased array techniques include: 2D and 1.5D arrays for improved beam shaping and focusing; curved arrays, also for better sizing; special TRL-PA (Transmit-Receive Longitudinal Wave-Phased Array) probes for austenitic steels; additional beams for special inspections. Examples of these inspections on welds will be given. Overall, a combination of phased arrays with TOFD or back diffraction allows the operator to perform cost-effective inspections with high reliability, repeatability, good defect sizing and full data storage.

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Ultrasonic backscatter sizing using phased array – developments in tip diffraction flaw sizing

Cited by 18 publications

References 4 publications

On the application of laser shock peening for retardation of surface fatigue cracks in laser beam‐welded AA6056

On the application of laser shock peening for retardation of surface fatigue cracks in laser beam‐welded AA6056

Implementation of American Association of State Highway and Transportation Officials/American Welding Society D1.5 Phased Array Ultrasonic Weld Inspection Programs

A Complete Solution for Weld Inspections: Phased Arrays and Diffraction Sizing

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