A reference-free micro defect visualization using pulse laser scanning thermography and image processing

Yang, Jinyeol; Choi, Jaemook; Hwang, Soonkyu; An, Yun‐Kyu; Sohn, Hoon

doi:10.1088/0957-0233/27/8/085601

Cited by 17 publications

(12 citation statements)

References 19 publications

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“…Thermographic techniques play a significant role in the NDE of composite structures (Sfarra et al 2012, Pawar et al 2013, Sharath et al 2013, Boccardi et al 2016, Yang et al 2016a. Pulse and lock-in thermography are two common techniques reported by researchers (Meola et al 2004).…”

Section: Eddy Current Pulsed Thermographymentioning

confidence: 99%

Performance and non-destructive evaluation methods of airborne radome and stealth structures

Panwar

Lee

2018

Meas. Sci. Technol.

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In the past few years, great effort has been devoted to the fabrication of highly efficient, broadband radome and stealth (R&S) structures for distinct control, guidance, surveillance and communication applications for airborne platforms. The evaluation of non-planar aircraft R&S structures in terms of their electromagnetic performance and structural damage is still a very challenging task. In this article, distinct measurement techniques are discussed for the electromagnetic performance and non-destructive evaluation (NDE) of R&S structures. This paper deals with an overview of the transmission line method and free space measurement based microwave measurement techniques for the electromagnetic performance evaluation of R&S structures. In addition, various conventional as well as advanced methods, such as millimetre and terahertz wave based imaging techniques with great potential for NDE of load bearing R&S structures, are also discussed in detail. A glimpse of in situ NDE techniques with corresponding experimental setup for R&S structures is also presented. The basic concepts, measurement ranges and their instrumentation, measurement method of different R&S structures and some miscellaneous topics are discussed in detail. Some of the challenges and issues pertaining to the measurement of curved R&S structures are also presented. This study also lists various mathematical models and analytical techniques for the electromagnetic performance evaluation and NDE of R&S structures. The research directions described in this study may be of interest to the scientific community in the aerospace sectors.

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Section: Eddy Current Pulsed Thermographymentioning

confidence: 99%

Performance and non-destructive evaluation methods of airborne radome and stealth structures

Panwar

Lee

2018

Meas. Sci. Technol.

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“…As a fully non-contact inspection method, it has the advantages of high efficiency, being deployable remotely and being suitable for automation. The study objects of LIT contain the laser heating method [5][6][7] , thermal image processing [8][9][10] , and the defect characterizations [11][12][13] . Until now, several studies have been conducted on characterization of surface cracks by using the LIT method [14][15][16][17][18] .…”

Section: Introductionmentioning

confidence: 99%

Remote measurement and shape reconstruction of surface-breaking fatigue cracks by laser-line thermography

Qiu

Pei

Yang

et al. 2021

International Journal of Fatigue

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In this paper, a method for remote measurement and shape reconstruction of fatigue cracks by using laser-line thermography (LLT) technique is developed. A new feature parameter derived from the LLT signals is proposed to evaluate the length and estimate the general inner profile of a surface-breaking fatigue crack. An inversion analysis scheme based on conjugate gradient optimization algorithm is then applied to reconstruct the detailed inner profile and dimension of the crack. The reconstruction results with both numerically simulated LLT signals and experimental signals proved the feasibility of proposed inversion scheme and remote LLT method. Based on methods of this paper, not only the size of cracks can be quantitatively evaluated, but the inner profile is also reconstructed for cracks in different shapes from the LLT signals.

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“…By scanning the laser spot along the sample surface at constant velocity (the so-called flying spot thermography), large parts can be analyzed in a fast way [ 1 , 2 ]. This method is well suited to image cracks by showing the crack length along the surface [ 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 ]. A more challenging task is to evaluate the width and depth of the detected crack.…”

Section: Introductionmentioning

confidence: 99%

Sizing the Depth and Width of Narrow Cracks in Real Parts by Laser-Spot Lock-In Thermography

Colom

Rodríguez‐Aseguinolaza

Mendioroz

et al. 2021

Materials

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We present a complete characterization of the width and depth of a very narrow fatigue crack developed in an Al-alloy dog bone plate using laser-spot lock-in thermography. Unlike visible micrographs, which show many surface scratches, the thermographic image clearly identifies the presence of a single crack about 1.5 mm long. Once detected, we focus a modulated laser beam close to the crack and we record the temperature amplitude. By fitting the numerical model to the temperature profile across the crack, we obtain both the width and depth simultaneously, at the location of the laser spot. Repeating the process for different positions of the laser spot along the crack length, we obtain the distribution of the crack width and depth. We show that the crack has an almost constant depth (0.7 mm) and width (1.5 μm) along 0.7 mm and features a fast reduction in both quantities until the crack vanishes. The results prove the ability of laser-spot lock-in thermography to fully characterize quantitatively narrow cracks, even below 1 μm.

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A reference-free micro defect visualization using pulse laser scanning thermography and image processing

Cited by 17 publications

References 19 publications

Performance and non-destructive evaluation methods of airborne radome and stealth structures

Performance and non-destructive evaluation methods of airborne radome and stealth structures

Remote measurement and shape reconstruction of surface-breaking fatigue cracks by laser-line thermography

Sizing the Depth and Width of Narrow Cracks in Real Parts by Laser-Spot Lock-In Thermography

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