Qualitätssicherung für Rissfüllungen: ein neuer Ansatz mit bildgebenden Ultraschallverfahren

Friese, Martin; Vogdt, Frank U.; Wiggenhauser, Herbert

doi:10.1002/best.201100029

Cited by 2 publications

(1 citation statement)

References 3 publications

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“…For example, component back-walls, reinforcement bars and horizontal delaminations were successfully imaged with shear wave arrays [11]. However, though the depth of notches was successfully imaged with DPC shear wave arrays, depth measurement of real cracks was not successful so far [12].…”

Section: Introductionmentioning

confidence: 99%

Evaluation of retroreflective corner echo for detection of surface breaking cracks in concrete by ultrasound

Rabe¹,

Pudovikov²,

Wiggenhauser³

et al. 2022

eJNDT

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The retroreflective corner echo is used, for example, in ultrasonic non-destructive testing of metals to find fatigue cracks in tubes or shafts. If the much weaker crack tip signal is additionally detected, the crack length can also be determined. A corner reflection occurs in cases of surface breaking cracks with predominantly perpendicular orientation to the surface. The intensity of the corner reflection depends on the angle of incidence and on the ultrasonic wave mode used. For the reliable detection of vertical surface breaking cracks in metals, transversal waves are commonly used, which propagate at an angle of 37° to 53° to the inspection surface. As shown in this contribution, the wide spread low frequency ultrasonic arrays with dry point contact sources available for ultrasonic testing of concrete also allow to receive corner echoes. These devices generate transversal waves in concrete structures with a large divergence of the sound field. A series of experiments was carried out with such dry point contact arrays on concrete specimens with artificial test defects and controlled induced cracks of different depths. The ultrasonic time-of-flight signals were recorded, exported and reconstructed utilising the SAFT (Synthetic Aperture Focusing Technique) algorithm. The SAFT reconstruction parameters were adjusted to visualize the corner echo indication. As will be shown, with this targeted processing, the reproducible detection of surface breaking cracks in concrete is possible. The retroreflective corner echo can thus be exploited in civil engineering for non-destructive inspection of concrete.

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Section: Introductionmentioning

confidence: 99%

Evaluation of retroreflective corner echo for detection of surface breaking cracks in concrete by ultrasound

Rabe¹,

Pudovikov²,

Wiggenhauser³

et al. 2022

eJNDT

View full text Add to dashboard Cite

show abstract

Using the Corner Reflection for Depth Evaluation of Surface Breaking Cracks in Concrete by Ultrasound

et al. 2023

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The corner echo is a well-known effect in ultrasonic testing, which allows detection of surface breaking cracks with predominantly perpendicular orientation to the surface as, for example, corrosion cracks in metal pipes or shafts. This echo is formed by two planes, the surface of the crack and the surface which the crack breaks. It can also be classified as a half-skip method, since a reflection of the pulse occurs on the backwall before the reflection at the defect takes place. In combination with the diffraction from the crack tip, the corner echo also allows crack sizing. As shown in this paper, the corner reflection can be used in civil engineering for nondestructive inspection of concrete. Commercially available low frequency ultrasonic arrays with dry point contact sources generate SH transversal waves with sufficient divergence of the sound field in order to detect corner reflections. Ultrasonic line-scans and area-scans were acquired with a linear array on flat concrete specimens, and the data were reconstructed by the Synthetic aperture focusing technique. If the angles and the area of reconstruction are chosen accordingly, the corner echo reflection can be distinguished from other ultrasonic information. The corner echo can thus be used as a method for deciding whether a crack is a partial-depth crack or a full-depth crack and thus for obtaining a statement about crack depth. This paper presents corresponding experimental results obtained on concrete specimens with artificial test defects and cracks induced under controlled conditions.

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Qualitätssicherung für Rissfüllungen: ein neuer Ansatz mit bildgebenden Ultraschallverfahren

Cited by 2 publications

References 3 publications

Evaluation of retroreflective corner echo for detection of surface breaking cracks in concrete by ultrasound

Evaluation of retroreflective corner echo for detection of surface breaking cracks in concrete by ultrasound

Using the Corner Reflection for Depth Evaluation of Surface Breaking Cracks in Concrete by Ultrasound

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