FEM-assisted shearography with spatially modulated heating for non-destructive testing of thick composites with deep defects

Tao, Nan; Anisimov, Andrei G.; Groves, Roger M.

doi:10.1016/j.compstruct.2022.115980

Cited by 15 publications

(4 citation statements)

References 34 publications

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“…It should be noted that the depth of the defects (blind holes) is defined in this paper as the remaining thickness of the material after drilling and not the depth of the blind holes. Also, these holes were drilled with conventional drills (cone of 135 deg), so these are not strictly the flat bottom holes that are often used as reference defects for non-destructive testing 4,12,13 . Units in mm.…”

Section: Methodsmentioning

confidence: 99%

“…As mentioned, even though applications for shearography NDT of thin composite materials were well discussed in the literature, an inspection of thicker composites has been conducted by relatively few researchers 10,11 . More recently, Tao et.al 12,13 have performed a numerical-experimental study on the defect detection capability in thick fiber-reinforced composite laminates. While it successfully detected defects in thick materials, the size of detected defects (flat bottom holes) was relatively large (60 mm in diameter and 30 mm in depth) 12 .…”

Section: Introductionmentioning

confidence: 99%

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Comparative performance of high and medium resolution cameras for defect detection in carbon-fiber reinforced composites by digital shearography

Abedin¹,

Tao²,

Anisimov³

et al. 2023

Optical Measurement Systems for Industrial Inspection XIII

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The performance of defect detection in composite materials using digital shearography is important for correct decisionmaking in non-destructive testing. In this work, we compared a high-resolution 24-megapixel digital still camera (DSLR) and a conventional medium-resolution 5-megapixel camera to determine the detectability of blind holes in an aerospacegraded carbon-fiber reinforced polymer (CFRP) sample. The hole diameters ranged from 0.2 to 3 mm with a material thickness of 4 mm and the test sample dimensions of 200×200 mm. The sample was heated and observed from the front (defect-free side) by three halogen lamps for 5 minutes in pulsed heating mode. Speckle interferograms were acquired during the heating and cooling phases from both cameras simultaneously using identical shearing interferometers and shearing distances. Phase maps were calculated using the 4+4 temporal phase step algorithm and then unwrapped. Further, defect-induced deformation (DID) phase maps were obtained by polynomial curve fitting. The DID phase maps obtained from the two cameras were compared. Blind holes with diameters up to 1 mm were detected, which are one of the smallest defects detected with shearography and reported in literature. In addition, the DLSR camera was able to detect holes of 0.8 mm in diameter. We observed that nearly comparable detection capabilities were obtained from both cameras, even though the spatial resolution of the second camera (DLSR) was 5 times higher. Possible reasons of this limitation include effects such as fiber-related deformation in CFRP and speckle noise.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Comparative performance of high and medium resolution cameras for defect detection in carbon-fiber reinforced composites by digital shearography

Abedin¹,

Tao²,

Anisimov³

et al. 2023

Optical Measurement Systems for Industrial Inspection XIII

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“…These strain variations were continuously monitored during cooling with the shearing cameras simultaneously to result in shearography phase maps, which were further processed and stitched together to result in continuous inspection maps. Each phase map was also compensated to remove the significant global deformation of the canvas 15,16 .…”

Section: Experimental Inspection Systemmentioning

confidence: 99%

Application of shearography with thermal loading for the structural inspection of Rembrandt’s Night Watch

Tao,

Anisimov,

van Duijn

et al. 2023

Optics for Arts, Architecture, and Archaeology (O3A) IX

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The assessment of the structural condition of cultural heritage objects is important for conservation interventions and their long-term preservation. This investigation concerns The Night Watch (1642), a large-format 17 th -century canvas painting by Rembrandt van Rijn that is on display in the Rijksmuseum, Amsterdam. This painting, which has a complex treatment history, has various damaged areas and has undergone three wax-resin relinings. In 1975 the canvas was slashed twelve times with a serrated dinner knife, including several long slashes in the area of Captain Frans Banninck Cocq's breeches. In 2021, prior to a proposed new structural intervention involving retensioning of the canvas, it was important to evaluate the structural condition of the repaired slashes and of another repair, specifically an old canvas insert in the drum. For this, an in-situ inspection was carried out in the Rijksmuseum as a part of Operation Nightwatch. 3D shearography instrument with thermal loading was used to inspect these two areas of interest on the reverse of The Night Watch. The results showed that the out-of-plane strain in the breeches does not show any large deviations, which alleviated conservators' concerns about the adhesion of the lining canvas and stability of previous repairs in this region. The patch in the drum showed higher out-of-plane strain variations. This was explained by the lower quality of the patched canvas compared to the repaired slashes in the breeches of Banninck Cocq. Overall, 3D shearography provided valuable inspection results for assurances regarding the structural integrity of the 1975 repairs and the wax-resin lining in The Night Watch, reducing the risks and providing the confidence to proceed with the planned retensioning of the canvas.

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“…Its potential for the detection and localisation of different types of defects (calibrated and real defects) in 4 mm-thick [0, ±45, 90] s laminates was demonstrated, with good agreement with the real description of the studied defects [ 35 ]. For thick composite materials (more than 50 mm thickness), shearography also demonstrated the capability of detection and localisation of defects such as flat bottom holes with thermal loading stimulation [ 36 , 37 ]. A simulation dataset and hybrid training, based on digital shearography images, in deep learning, were performed for defect detection in various kinds of materials (epoxy carbon, E glass fibre, ABS thermoplastic, etc.)…”

Section: Surface Non-destructive Testing Techniquesmentioning

confidence: 99%

Non-Destructive Health Monitoring of Structural Polymer Composites: Trends and Perspectives in the Digital Era

Chaki

Krawczak

2022

Materials

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Non-destructive testing (NDT) techniques are usually used for the characterisation of defects arising in polymer composites during manufacturing or in-service use. However, each of these NDT techniques cannot always allow a full diagnosis of the material’s or component’s structural health. Thus, several techniques have to be combined in order to improve the diagnosis of the damaged state of composite structures and their evolution during the part’s life span. This opinion paper proposes a critical overview of the use and applicability of these NDT techniques for the detection and characterisation of damage to structural composite materials in view of in-service performance assessment and residual durability prognosis. It also addresses some current trends of structural health monitoring (SHM) of these materials, such as sensor–actuator embedding and NDT data fusion, and draws future perspectives on how composite SHM could evolve in the digital era, taking advantage of artificial intelligence, Internet of Things and big data to implement digital twins.

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FEM-assisted shearography with spatially modulated heating for non-destructive testing of thick composites with deep defects

Cited by 15 publications

References 34 publications

Comparative performance of high and medium resolution cameras for defect detection in carbon-fiber reinforced composites by digital shearography

Comparative performance of high and medium resolution cameras for defect detection in carbon-fiber reinforced composites by digital shearography

Application of shearography with thermal loading for the structural inspection of Rembrandt’s Night Watch

Non-Destructive Health Monitoring of Structural Polymer Composites: Trends and Perspectives in the Digital Era

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