Laser Ultrasonics : A Non Contacting NDT System

Pétillon, Odile; Dupuis, J.-P.; David, D.; Voillaume, Hubert; Trétout, H.

doi:10.1007/978-1-4615-1987-4_151

Cited by 8 publications

(3 citation statements)

References 4 publications

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“…Laser excitation presents an alternative broadband, contactfree means of excitation [28,29], but comes with higher costs and extensive safety regulations.…”

Section: Conclusion and Discussionmentioning

confidence: 99%

Ultrasonic and Impact-Echo Testing for the Detection of Scaling in Geothermal Pipelines

2023

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The efficiency and longevity of components in geothermal plants are significantly reduced by mineral deposition in pipes, also known as scaling [1]. A number of methods are used to monitor fouling (a broader term for all types of organic and inorganic deposition) in other industries, such as the oil, gas and food industries. These include direct and indirect, offline, in-situ and online, as well as inline methods, each of which have pros and cons [2, 3]. An effective monitoring solution specific to the high temperature conditions in geothermal plants, which optimises maintenance and cleaning measures in dependency of scaling, has yet to be developed. In this paper, two non-destructive testing techniques: contact ultrasonic testing (UT) and impact-echo (IE) testing are investigated in their viability as methods to detect scaling growth in geothermal plants. A descaling measurement was conducted on a heavily scaled segment of an obsolete pipeline from the production well of the geothermal power plant in Sauerlach, Germany. The pipeline segment was inserted in a test rig and the scaling was gradually etched away using an acidic solution. At regular time intervals, the scaling thickness was measured mechanically and contact UT as well as IE measurements were carried out. The testing apparatus was designed to withstand high temperatures ($${140}\,^{\circ }{\text {C}}$$ 140 ∘ C at the inlet pipe surface) and to be easy to install whilst being cost-efficient. Both techniques yielded usable results with submillimeter resolution. The advantages and limitations of the two methods are discussed. Impact-echo testing, in particular, can be automated and presents a simple and cost-efficient scaling monitoring option.

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“…Laser excitation presents an alternative broadband, contactfree means of excitation [28,29], but comes with higher costs and extensive safety regulations.…”

Section: Conclusion and Discussionmentioning

confidence: 99%

Ultrasonic and Impact-Echo Testing for the Detection of Scaling in Geothermal Pipelines

2023

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“…Technology other than optical method has also been reported, such as ultrasound monitoring [10], but also need complex setup in the AM system. Laser ultrasound is another technology that uses laser to generate ultrasonic waves for on-destructive test (NDT), and its principle is similar to ultrasonic imaging, except that the generation or detection of the ultrasonic signal is from laser beams [11,12]. In this paper, we propose an easy to implement and cost effective method for in-situ monitoring of the laser assisted ceramic AM fabrication process with very little modification of a ceramic AM system, employing photoacoustic (PA) imaging technique.…”

Section: Introductionmentioning

confidence: 99%

A photoacoustic imaging method for in-situ monitoring of laser assisted ceramic additive manufacturing

Cheng

Lei

Xiao

2019

Optics & Laser Technology

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We propose an in-situ monitoring method of laser assisted ceramic additive manufacturing (AM) fabrication process using photoacoustic (PA) imaging technique. This method is potentially very practical and of low cost, as it can be easily implemented with little modification to the original AM system. A major advantage of this method is that it does not require any complex or expensive component to be installed, just need a microphone to be setup near the work-piece and a data processing program to analyse the acoustic data. By collecting the photoacoustic wave that produced by the laser scanning during the AM process, a spectrogram of the acoustic signal can be generated using short-time Fourier transform (STFT). The PA signal can be extracted by specifying the modulation frequency of the laser in the spectrogram. Combining with the scanning position of the laser beam, the PA image of the layer under processing can be obtained. Detection of two kinds of defects (metal defect and dried paste defect) have been demonstrated. Although there are many other kinds of possible defects in additive manufacturing processes, this method could be a practical and low cost way to monitor most of them with proper choice of parameters of the laser and detection system. The parameters of the system that can influence the PA image quality have also been discussed.

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“…Intrinsically, this technique can be applied for only conductive material so that it is not suitable for many civil infrastructure components. In laser ultrasound, laser induced ultrasound, i.e., inspection structure itself is ultrasound transmitter and reflected ultrasound is picked up by optical method [7]. This technique is suitable to detect huge and complex geometry and there is no incident angle problem.…”

Section: Introductionmentioning

confidence: 99%

Review of Noncontact Ultrasonic Measurement System for Structural Health Monitoring

Kobayashi¹

2019

ACET

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Non-destructive testing (NDT) of infrastructure such as bridges and tunnels has become more important since it has aging problem and traffic was heavier than expected. Thin film ultrasonic sensors would be attractive because it is easy to integrate on huge structure. However, NDT of huge structure is still challenging because of sensor accessibility. Semi-noncontact ultrasonic sensors were proposed in this manuscript. 20cm diameter copper coil transmit/receive electrical signal from a pulser/receiver instrument and a thin film ultrasonic sensor and reflected echo from 12.7mm thick steel plate successfully. By this method, measurement using drone could be possible and it increases application possibility for huge infrastructure monitoring.

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Laser Ultrasonics : A Non Contacting NDT System

Cited by 8 publications

References 4 publications

Ultrasonic and Impact-Echo Testing for the Detection of Scaling in Geothermal Pipelines

Ultrasonic and Impact-Echo Testing for the Detection of Scaling in Geothermal Pipelines

A photoacoustic imaging method for in-situ monitoring of laser assisted ceramic additive manufacturing

Review of Noncontact Ultrasonic Measurement System for Structural Health Monitoring

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