Synthetic aperture focusing technique for correction of poorly-focused ultrasonic pressure tube inspection data

Research output: Contribution to conferencePaper

Abstract

Defect size measurement of ultrasonic pressure tube inspection within the CANDU (CANada Deuterium Uranium) reactor has challenges when the transducer is poorly-focused with respect to the tube surface. Environmental effects, such as diametrical creep and sagging over time can lead to displacement of the tube surface from the optimal inspection position. In order to improve the accuracy of defect sizing, a Synthetic Aperture Focusing Technique (SAFT) method based on single element focused transducer inspection is proposed. In SAFT processing, the transducer focal point operates as a virtual source to transmit ultrasound with a corresponding beam angle relating to the transducer aperture and focal length. To correct for the image distortion caused by poor focusing in the region beyond the transducer focal point, every pixel value of the B-scan image is calculated using the delay-and-sum of echo signals collected at multiple positions on the synthetic aperture, while the synthetic aperture length is determined by the beam angle of the virtual source. Application of the SAFT approach significantly enhances image resolution through which more accurate feature size measurements can be determined, with the accuracy of a -6dB measured surface defect width improved by 50% compared to the original B-scan image when the surface is located more than 1.5mm beyond the focal point.

Conference

Conference9th European Workshop on Structural Health Monitoring Series (EWSHM)
Abbreviated titleEWSHM
CountryUnited Kingdom
CityManchester
Period10/07/1813/07/18
Internet address

Fingerprint

Synthetic apertures
Transducers
Inspection
Ultrasonics
Defects
Surface defects
Deuterium
Image resolution
Uranium
Environmental impact
Creep
Pixels
Processing

Keywords

  • SAFT
  • CANDU pressure tubes
  • ultrasonic NDE

Cite this

Zhao, H., Gachagan, A., Dobie, G., Wallace, C., & West, G. (2018). Synthetic aperture focusing technique for correction of poorly-focused ultrasonic pressure tube inspection data. Paper presented at 9th European Workshop on Structural Health Monitoring Series (EWSHM) , Manchester, United Kingdom.
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title = "Synthetic aperture focusing technique for correction of poorly-focused ultrasonic pressure tube inspection data",
abstract = "Defect size measurement of ultrasonic pressure tube inspection within the CANDU (CANada Deuterium Uranium) reactor has challenges when the transducer is poorly-focused with respect to the tube surface. Environmental effects, such as diametrical creep and sagging over time can lead to displacement of the tube surface from the optimal inspection position. In order to improve the accuracy of defect sizing, a Synthetic Aperture Focusing Technique (SAFT) method based on single element focused transducer inspection is proposed. In SAFT processing, the transducer focal point operates as a virtual source to transmit ultrasound with a corresponding beam angle relating to the transducer aperture and focal length. To correct for the image distortion caused by poor focusing in the region beyond the transducer focal point, every pixel value of the B-scan image is calculated using the delay-and-sum of echo signals collected at multiple positions on the synthetic aperture, while the synthetic aperture length is determined by the beam angle of the virtual source. Application of the SAFT approach significantly enhances image resolution through which more accurate feature size measurements can be determined, with the accuracy of a -6dB measured surface defect width improved by 50{\%} compared to the original B-scan image when the surface is located more than 1.5mm beyond the focal point.",
keywords = "SAFT, CANDU pressure tubes, ultrasonic NDE",
author = "Huan Zhao and Anthony Gachagan and Gordon Dobie and Christopher Wallace and Graeme West",
year = "2018",
month = "11",
day = "1",
language = "English",
note = "9th European Workshop on Structural Health Monitoring Series (EWSHM) : EWSHM 2018, EWSHM ; Conference date: 10-07-2018 Through 13-07-2018",
url = "http://www.bindt.org/events/ewshm-2018/",

}

Zhao, H, Gachagan, A, Dobie, G, Wallace, C & West, G 2018, 'Synthetic aperture focusing technique for correction of poorly-focused ultrasonic pressure tube inspection data' Paper presented at 9th European Workshop on Structural Health Monitoring Series (EWSHM) , Manchester, United Kingdom, 10/07/18 - 13/07/18, .

Synthetic aperture focusing technique for correction of poorly-focused ultrasonic pressure tube inspection data. / Zhao, Huan; Gachagan, Anthony; Dobie, Gordon; Wallace, Christopher; West, Graeme.

2018. Paper presented at 9th European Workshop on Structural Health Monitoring Series (EWSHM) , Manchester, United Kingdom.

Research output: Contribution to conferencePaper

TY - CONF

T1 - Synthetic aperture focusing technique for correction of poorly-focused ultrasonic pressure tube inspection data

AU - Zhao, Huan

AU - Gachagan, Anthony

AU - Dobie, Gordon

AU - Wallace, Christopher

AU - West, Graeme

PY - 2018/11/1

Y1 - 2018/11/1

N2 - Defect size measurement of ultrasonic pressure tube inspection within the CANDU (CANada Deuterium Uranium) reactor has challenges when the transducer is poorly-focused with respect to the tube surface. Environmental effects, such as diametrical creep and sagging over time can lead to displacement of the tube surface from the optimal inspection position. In order to improve the accuracy of defect sizing, a Synthetic Aperture Focusing Technique (SAFT) method based on single element focused transducer inspection is proposed. In SAFT processing, the transducer focal point operates as a virtual source to transmit ultrasound with a corresponding beam angle relating to the transducer aperture and focal length. To correct for the image distortion caused by poor focusing in the region beyond the transducer focal point, every pixel value of the B-scan image is calculated using the delay-and-sum of echo signals collected at multiple positions on the synthetic aperture, while the synthetic aperture length is determined by the beam angle of the virtual source. Application of the SAFT approach significantly enhances image resolution through which more accurate feature size measurements can be determined, with the accuracy of a -6dB measured surface defect width improved by 50% compared to the original B-scan image when the surface is located more than 1.5mm beyond the focal point.

AB - Defect size measurement of ultrasonic pressure tube inspection within the CANDU (CANada Deuterium Uranium) reactor has challenges when the transducer is poorly-focused with respect to the tube surface. Environmental effects, such as diametrical creep and sagging over time can lead to displacement of the tube surface from the optimal inspection position. In order to improve the accuracy of defect sizing, a Synthetic Aperture Focusing Technique (SAFT) method based on single element focused transducer inspection is proposed. In SAFT processing, the transducer focal point operates as a virtual source to transmit ultrasound with a corresponding beam angle relating to the transducer aperture and focal length. To correct for the image distortion caused by poor focusing in the region beyond the transducer focal point, every pixel value of the B-scan image is calculated using the delay-and-sum of echo signals collected at multiple positions on the synthetic aperture, while the synthetic aperture length is determined by the beam angle of the virtual source. Application of the SAFT approach significantly enhances image resolution through which more accurate feature size measurements can be determined, with the accuracy of a -6dB measured surface defect width improved by 50% compared to the original B-scan image when the surface is located more than 1.5mm beyond the focal point.

KW - SAFT

KW - CANDU pressure tubes

KW - ultrasonic NDE

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M3 - Paper

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Zhao H, Gachagan A, Dobie G, Wallace C, West G. Synthetic aperture focusing technique for correction of poorly-focused ultrasonic pressure tube inspection data. 2018. Paper presented at 9th European Workshop on Structural Health Monitoring Series (EWSHM) , Manchester, United Kingdom.