Application of the hybrid laser ultrasonic method in rail inspection

Zhao, Yang; Sun, Ji Hua; Ma, Jian; Liu, S; Guo, Rui-biao; Song, Jinhui; Jia, Zhong Qing

doi:10.1784/insi.2014.56.7.360

Cited by 24 publications

(12 citation statements)

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“…Then, mapping wavelet coefficients use the soft or hard threshold λ at each scale. Inverse discrete wavelet translation (IDWT) is employed to obtain the estimated signal at last 12 …”

Section: Noise Reduction By Wstmmentioning

confidence: 99%

Laser ultrasonic evaluation of bonding layer in thermal barrier coating

2015

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A noncontact laser ultrasonic method is provided for nondestructive characterization of bonding layer (BL) in thermal barrier coating (TBC). A physical mode of thin multi-layered structure is established for the case of received ultrasonic waveform consisting of reverberant overlapping echoes. Then, the transmission coefficient of the mode was derived in this work. Experiments have been performed on TBC specimens using the proposed method. The specimens are produced by electronic beam physical vapor deposition (EBPVD) method. A pulsed laser with width of 10 ns was used to generate ultrasonic while a two wave mixing (TWM) interferometer was employed to receive the ultrasonic signals. Wavelet soft-threshold method (WSTM) was introduce to improve the signal to noise ratio of laser ultrasonic testing TBC. The transmission coefficient spectrum of TBC was obtained to measure the longitudinal velocity of BL. Further, the numerical fitting method is used to determine the attenuation of BL. The proposed method is used to evaluate TBC after 1, 10 and 100 times, and the experimental results are in according with the SEM observations. This method is able to nondestructively characterize BL in TBC system, and is important to practical engineering application.

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“…Then, mapping wavelet coefficients use the soft or hard threshold λ at each scale. Inverse discrete wavelet translation (IDWT) is employed to obtain the estimated signal at last 12 …”

Section: Noise Reduction By Wstmmentioning

confidence: 99%

Laser ultrasonic evaluation of bonding layer in thermal barrier coating

2015

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“…Several research groups have investigated LUT for the inspection of rail tracks [ 9 , 10 , 11 , 12 , 13 , 14 , 15 ]. However, in these works, for the non-contact detection of laser-generated ultrasonic waves, mostly EMAT [ 9 ] and air-coupled transducers [ 11 , 12 ] were used. One of these transducer’s major drawbacks is the limited lift-off distance because the signal amplitude and signal-to-noise ratio (SNR) significantly reduce as the distance between the sample and transducer increases.…”

Section: Introductionmentioning

confidence: 99%

“…The laser ultrasonic technique (LUT) is one of the latest candidates for non-destructive testing. Several research groups have investigated LUT for the inspection of rail tracks [9][10][11][12][13][14][15]. However, in these works, for the non-contact detection of laser-generated ultrasonic waves, mostly EMAT [9] and air-coupled transducers [11,12] were used.…”

Section: Introductionmentioning

confidence: 99%

Non-Contact Inspection of Railhead via Laser-Generated Rayleigh Waves and an Enhanced Matching Pursuit to Assist Detection of Surface and Subsurface Defects

Ghafoor

Tse

Rostami

et al. 2021

Sensors

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Laser ultrasonic technology can provide a non-contact, reliable and efficient inspection of train rails. However, the laser-generated signals measured at the railhead are usually contaminated with a high level of noise and unwanted wave components that complicate the identification of defect echoes in the signal. This study explores the possibility of combining laser ultrasonic technology (LUT) and an enhanced matching pursuit (MP) to achieve a fully non-contact inspection of the rail track. A completely non-contact laser-based inspection system was used to generate and sense Rayleigh waves to detect artificial surface horizontal, surface edge, subsurface horizontal and subsurface vertical defects created at railheads of different dimensions. MP was enhanced by developing two novel dictionaries, which include a finite element method (FEM) simulation dictionary and an experimental dictionary. The enhanced MP was used to analyze the experimentally obtained laser-generated Rayleigh wave signals. The results show that the enhanced MP is highly effective in detecting defects by suppressing noise, and, further, it could also overcome the deficiency in the low repeatability of the laser-generated signals. The comparative analysis of MP with both the FEM simulation and experimental dictionaries shows that the enhanced MP with the FEM simulation dictionary is highly efficient in both noise removal and defect detection from the experimental signals captured by a laser-generated ultrasonic inspection system. The major novelty contributed by this research work is the enhanced MP method with the developments of, first, an FEM simulation dictionary and, second, an experimental dictionary that is especially suited for Rayleigh wave signals. Third, the enhanced MP dictionaries are created to process the Rayleigh wave signals generated by laser excitation and received using a 3D laser scanner. Fourth, we introduce a pioneer application of such laser-generated Rayleigh waves for inspecting surface and subsurface detects occurring in train rails.

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“…Typically, nanosecond laser pulses are used to generate ultrasonic sources in the megahertzrange for the thickness measurement and defect inspection of the bulk materials, while femtosecond laser systems are necessary for GHz range which is suitable to evaluate the thin layer in the order of micrometer even nanometer [2]. The detection of ultrasound generated by pulsed laser can be carried out by means of noncontact methods via optical interferometer, optical beam deflection (GCLAD) or knife edge detection [3]. Optical detection of ultrasound is attractive because it can provide absolute measurement of ultrasonic signal with high detection bandwidth in a noncontact way.…”

Section: Introductionmentioning

confidence: 99%

Applications of laser ultrasonic technique on nondestructive testing and evaluation of materials

et al. 2018

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Nondestructive testing (NDT) is a wide group of analysis techniques used in science and industry to evaluate the properties of a material, component or system without causing damage. As one of unconventional NDT technology, laser ultrasonic technique (LUT) have played an important role in inspecting the materials in some extreme environments, such as high temperature, high pressure, corrosion, radioactive and etc. LUT uses lasers to generate and detect ultrasonic waves in a noncontact way. Thus, compared with the traditional ultrasonic technique, LUT has the advantages of high precision, high sensitivity without requirement for geometry of target material. So far, LUT has been well applied to composite inspections for the aerospace industry and on-line hot tube thickness measurements for the metallurgical industry. This talk describes the application of LUT on flaws detection in rail and thermal barrier coatings.

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Application of the hybrid laser ultrasonic method in rail inspection

Cited by 24 publications

References 0 publications

Laser ultrasonic evaluation of bonding layer in thermal barrier coating

Laser ultrasonic evaluation of bonding layer in thermal barrier coating

Non-Contact Inspection of Railhead via Laser-Generated Rayleigh Waves and an Enhanced Matching Pursuit to Assist Detection of Surface and Subsurface Defects

Applications of laser ultrasonic technique on nondestructive testing and evaluation of materials

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