Non-Destructive Evaluation of Depth of Surface Cracks Using Ultrasonic Frequency Analysis

Her, Shiuh-Chuan; Lin, Sheng-Tung

doi:10.3390/s140917146

Cited by 26 publications

(14 citation statements)

References 30 publications

(33 reference statements)

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“…indicates the low frequency component, while indicates the high frequency component. The signal can be decomposed into levels and can be expressed by (4) where is an integer.…”

Section: Wavelet Analysismentioning

confidence: 99%

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Wavelet analysis of poorly-focused ultrasonic signal of pressure tube inspection in nuclear industry

Zhao¹,

Gachagan²,

Dobie³

et al. 2018

AIP Conference Proceedings

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Abstract. Pressure tube fabrication and installment challenges combined with natural sagging over time can produce issues with probe alignment for pressure tube inspection of the primary circuit of CANDU reactors. The ability to extract accurate defect depth information from poorly-focused ultrasonic signals would reduce additional inspection procedures, which leads to a significant time and cost saving. Currently, the defect depth measurement protocol is to simply calculate the time difference between the peaks of the echo signals from the tube surface and the defect from a single element probe focused at the back-wall depth. When alignment issues are present, incorrect focusing results in interference within the returning echo signal. This paper proposes a novel wavelet analysis method that employs the Haar wavelet to decompose the original poorly focused A-scan signal and reconstruct detailed information based on a selected high frequency component range within the bandwidth of the transducer. Compared to the original signal, the wavelet analysis method provides additional characteristic defect information and an improved estimate of defect depth with errors less than 5%.

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“…indicates the low frequency component, while indicates the high frequency component. The signal can be decomposed into levels and can be expressed by (4) where is an integer.…”

Section: Wavelet Analysismentioning

confidence: 99%

“…The Fourier Transform is a foundation of many signal processing algorithms in the frequency domain. Her and Lin introduced a frequency analysis concept to evaluate the depth of surface cracks [4]. According to their research, the time difference could be deduced from the frequency spectrum associated with the bottom surface crack.…”

Section: Introductionmentioning

confidence: 99%

Wavelet analysis of poorly-focused ultrasonic signal of pressure tube inspection in nuclear industry

Zhao¹,

Gachagan²,

Dobie³

et al. 2018

AIP Conference Proceedings

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“…A direct idea of sizing the surface-breaking crack in ultrasonic testing is to measure the flight time of the diffracted echoes and calculate the crack depth with the knowledge of the geometry of the component, this has led to the development of the Impulse-Echo-Technique (IET) and the Time of Flight Diffraction Technique (TOFD). Shiuh-Chuan Her et al [6], [7] applied the IET to conduct the through-wall detection of the surface-breaking cracks, while Baby et al [8] evaluated the depth of the surface-breaking crack on the far surface using the TOFD. The results of their work showed that these methods can achieve a good accuracy for a crack larger than one wavelength but have a poor performance for the cracks smaller than one wavelength [6], [8].…”

Section: Introductionmentioning

confidence: 99%

“…Shiuh-Chuan Her et al [6], [7] applied the IET to conduct the through-wall detection of the surface-breaking cracks, while Baby et al [8] evaluated the depth of the surface-breaking crack on the far surface using the TOFD. The results of their work showed that these methods can achieve a good accuracy for a crack larger than one wavelength but have a poor performance for the cracks smaller than one wavelength [6], [8].…”

Section: Introductionmentioning

confidence: 99%

The Application of the Factorization Method to the Subsurface Imaging of Surface-Breaking Cracks

Zhang

Huthwaite

Lowe

2018

IEEE Trans. Ultrason., Ferroelect., Freq. Contr.

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Abstract-A common location for cracks to appear is at the surface of a component; at the near surface, many nondestructive evaluation (NDE) techniques are available to inspect for these, but at the far surface this is much more challenging. Ultrasonic imaging is proposed to enable far surface defect detection, location and characterisation. One specific challenge here is the presence of a strong reflection from the backwall, which can often mask the relatively small response from a defect. In this paper, the Factorization Method (FM) is explored for the application of subsurface imaging of the surface-breaking cracks. In this application, the component has two parallel surfaces, the crack is initiated from the far side and the phased array is attached on the near side. Ideally, the pure scattered field from a defect is needed for the correct estimation of the scatterer through the FM algorithm. However, the presence of the backwall will introduce a strong specular reflection into the measured data which should be removed before applying the FM algorithm. A novel subtraction method was developed to remove the backwall reflection. The performance of the FM algorithm and this subtraction method were tested with the simulated and experimental data. The experimental results showed a good consistency with the simulated results. It is shown that the FM algorithm can generate high quality images to provide a good detection of the crack and an accurate sizing of the crack length. The subtraction method was able to provide a good backwall reflection removal in the case of small cracks (1-3 wavelengths).

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“…Bemstein et al also used the magnitude in frequency domain for crack characterisation. Her et al [38] found the crack leads to the time delay between the two pulses deduced from the frequency spectrum. Edwards et al [39] measured the depth of cracks using the amplitude of the first received echo in time-domain, showing the amplitude of the first echo decreases when the depth of the crack increases.…”

Section: Introductionmentioning

confidence: 99%

Crack characterisation using invariable feature extraction in stainless steel specimen used for absorber tubes of CSP applications via EMAT

et al. 2017

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Absorber tubes are one of the most critical components of parabolic trough Concentrated Solar Plants. Due to the high temperatures where these tubes perform at with concentration of sunlight, it is very likely to get damaged such as crack etc and lose functionality. Therefore, the monitoring via NDT techniques is essential for preventing them from being significantly defective and reducing maintenance cost. Non-contact method is one of the best inspection candidates, which is more reliable to the tubes at high temperature through a review and the access to the absorber tubes is limited. In this paper, the crack detection and quantification for stainless steel specimen used for absorber tube using Electromagnetic Acoustic Transducers is presented. Through numerical and experimental studies, features are extracted to quantify the crack. Among these features, the ratio between the first edge echo and the second crack echo (Ac2/Ae1) is investigated as invariable feature to factors such as electromagnetic coupling, lift-off distance between EMATs and the specimen etc. In addition, the feature Ac2/Ae1 has linear relationship with the depth of the crack when the depth is more than 0.75mm, which proves the feature Ac2/Ae1 is invariable for crack quantification via both numerical modelling and experimental studies.

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Non-Destructive Evaluation of Depth of Surface Cracks Using Ultrasonic Frequency Analysis

Cited by 26 publications

References 30 publications

Wavelet analysis of poorly-focused ultrasonic signal of pressure tube inspection in nuclear industry

Wavelet analysis of poorly-focused ultrasonic signal of pressure tube inspection in nuclear industry

The Application of the Factorization Method to the Subsurface Imaging of Surface-Breaking Cracks

Crack characterisation using invariable feature extraction in stainless steel specimen used for absorber tubes of CSP applications via EMAT

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