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Author

Petter Norli

Bio: Petter Norli is an academic researcher. The author has contributed to research in topics: Stress corrosion cracking & Ultrasonic sensor. The author has an hindex of 3, co-authored 8 publications receiving 44 citations.

Papers
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Journal ArticleDOI
TL;DR: Air-coupled ultrasonic through-transmission measurements on a steel plate with thicknesses 10.15 mm; 10.0 mm; 9.8 mm show that the resonances could be clearly identified after transmission through the steel plate, and that the frequencies of the resonance could be used to distinguish between the three plate thicknesses.

36 citations

Posted Content
TL;DR: In this paper, a method of measuring the thickness of steel plates using through transmission of an acoustic pulse is demonstrated using a stainless steel plate with regions of thickness 10:0 mm, 9:8 mm, and 9:6 mm.
Abstract: A method of measuring the thickness of steel plates using through transmission of an acoustic pulse is demonstrated. This study has been done on a stainless steel plate with regions of thickness 10:0 mm, 9:8 mm, and 9:6 mm, using broadband pulses with energy in 200 kHz to 600 kHz band. Ultimately the goal is to perform similar air-coupled thickness measurements in a single sided pitch-catch measurement setup. The spectra of the transmitted pulses show the first and second harmonics of the compressional waves in the plate. When compared to a plane wave model of a fluid layer embedded in air, the second harmonic of the plate resonance fits well with the expected value. However, the first harmonic deviates such that the plate appears thicker at this resonance. This is believed to be caused by the finite aperture of the transmitting transducer, causing deviations from a plane wave. Thickness differences of 0:2 mm between the different regions of the plate were shown to be resolved. A third peak was found in the spectra. The origin of this peaks has not been verified, but is believed to come from the third harmonic of the shear wave in the steel plate.

7 citations

Proceedings ArticleDOI
01 Sep 2017
TL;DR: In this article, a water-immersed 12 mm thick steel plate with machined crack-like, spark eroded notches (SEN) of 2 and 6 mm depth, and 10 and 20 mm lengths, were acoustically investigated with broadband transducers in a pitch-catch setup.
Abstract: A long-standing challenge in integrity management of gas pipelines is stress corrosion cracking (SCC). Such cracks are difficult to detect, calling for sensitive detection methods with good coverage. Recent advances in gas-coupled broad band ultrasound provide a potential method that is based on guided plate waves. The objective of this work is to describe and experimentally evaluate this method based on Halfwave's ART Scan® tool. A water-immersed 12 mm thick steel plate with machined crack-like, spark eroded notches (SEN) of 2 and 6 mm depth, and 10 and 20 mm lengths, were acoustically investigated with broadband (0.3–1.3 MHz) transducers in a pitch-catch setup. Received signals were acquired at 2D grid locations, and pointwise processing parameters were extracted. Summed signal power and a spectral parameter demonstrated the detection of the SENs. The received energy in a selected frequency band was 2.5 and 5.5 dB lower for the 2 and 6 mm deep SENs, respectively, compared to that of an undamaged part of the plate. Using a tomographic image inversion method, the received signals were combined and converted into images. Results of the 6 mm deep SEN showed good agreement with the actual size and location of the SEN. In conclusion, the potential to detect SCC by using an ART Scan® based set-up, combined with pointwise and image formation processing, was successfully demonstrated on test plates with machined crack-like defects.

4 citations

Proceedings ArticleDOI
01 Oct 2018
TL;DR: In this paper, the authors demonstrated the crack detection potential of using guided waves and gas-coupled broad band ultrasound by experimental detection of machined crack-like defects based on Halfwave's ART Scan® tool.
Abstract: Stress corrosion cracking (SCC) is a serious problem in gas pipelines. The detection of such cracks are difficult with currently available in-line inspection technologies. Recent work demonstrated the crack detection potential of using guided waves and gas-coupled broad band ultrasound by experimental detection of machined crack-like defects based on Halfwave's ART Scan® tool [1]. The present study experimentally investigated the detection of real SCC, with crack depths of up to 4.3 mm, on a real pipe, with a nominal wall thickness of 12.7mm, using broadband (0.3-1.3 MHz) transducers in a pitch-catch set-up. Acoustic signals were received by eight transducers, surrounding the transmitter, at cylindrical scan locations, and different processing parameters were extracted. 2D parameter scans displayed the crack and pitting corrosion areas. The summed power parameter resulted in signal differences of up to 8 dB for the crack area as compared to the surrounding area. In conclusion, the detection of real SCC by using an ART Scan® based set-up was successfully demonstrated on a real pipe section in water.

4 citations

Proceedings ArticleDOI
01 Oct 2019
TL;DR: In this article, a test scanner with 32 transmit/receive channels was developed to perform circumferential scans of 425 mm × 60° from the inside of pipe samples of diameters close to 36 inches.
Abstract: Stress corrosion cracking (SCC) is a serious threat to gas pipelines. Current in-line inspection tools have issues with the detection and sizing of small cracks. Advances in gas-coupled broadband ultrasound enable new detection methods based on Guided Ultrasonic Waves (GUW). Recently, the potential to detect SCC using Halfwave’s ART Scan® tool was successfully demonstrated on real pipe samples with SCC, submerged in water [1]. In this study, the ultrasonic detection of SCC is experimentally demonstrated, using pressurized gas at 60 bar as acoustic coupling medium. A custom-made test scanner with 32 transmit/receive channels was developed to perform circumferential scans of 425 mm × 60° from the inside of pipe samples of diameters close to 36 inches. The gaseous atmosphere of 60 bar (nitrogen) required the experiments to be conducted inside a pressure tank that contained both the test scanner and pipe samples. Broad-band pulses were transmitted, and signals were received from all scan positions. Processed parameters like spectral power and wall thickness estimates were calculated. 2D plots of processed parameters and reconstructed image results demonstrated the detection and sizing potential for real cracks, crack fields, and other surface irregularities.

3 citations


Cited by
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01 Jan 2016
TL;DR: In this paper, the authors present the principles of optics electromagnetic theory of propagation interference and diffraction of light, which can be used to find a good book with a cup of coffee in the afternoon, instead of facing with some infectious bugs inside their computer.
Abstract: Thank you for reading principles of optics electromagnetic theory of propagation interference and diffraction of light. As you may know, people have search hundreds times for their favorite novels like this principles of optics electromagnetic theory of propagation interference and diffraction of light, but end up in harmful downloads. Rather than enjoying a good book with a cup of coffee in the afternoon, instead they are facing with some infectious bugs inside their computer.

2,213 citations

Journal ArticleDOI
TL;DR: The applications of ACU to wood characterization with reference to wood quality aspects are summarized andCorrelations between the ACU parameters and the wood properties as well as the wood defects are dealt with in detail.

64 citations

Journal ArticleDOI
TL;DR: In this paper, a non-contact set-up based on laser excitation of ultrasound and detection with a broadband, air-coupled optical microphone is presented and tested on flax/PLA laminates.

30 citations

Journal ArticleDOI
TL;DR: This work presents two high‐frequency ultrasonic non‐destructive testing technologies, including piezoelectric pulse‐echo and laser‐ultrasonic methods, for detecting corrosion of Ni superalloy from the opposite side, and demonstrates the determination of corrosion layer thickness below ˜100&mgr;m.

23 citations