Determination of Defect Depth and Size Using Virtual Heat Sources in Pulsed Infrared Thermography

Manohar, Arun; Scalea, Francesco Lanza di

doi:10.1007/s11340-012-9670-9

Cited by 22 publications

(11 citation statements)

References 5 publications

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“…It was found that while both models performed with a similar degree of accuracy when predicting the experimental data the VHS model over predicted the peak contrast whereas, the current model under predicted the peak contrast. It is suggested that the VHS model over predicts the peak contrast in this case as the pulse strength used in the current work is lower than in [133] and as such lateral heat conduction may have an increasingly visible effect relative to the lower strength signal. …”

Section: Pulsed Thermography Model Resultsmentioning

confidence: 79%

“…A schematic of PhD Thesis 92 the data point locations is given in Figure 40, and the equivalent data was taken from both modelled and experimental results. The aluminium model has also been compared to another model recently published [133], which uses virtual heat sources (VHS) at defect locations to model surface temperature data. In [133] between DC and ND were compared between the two models and experimental data, see Figure 43.…”

Section: Pulsed Thermography Model Resultsmentioning

confidence: 99%

“…The aluminium model has also been compared to another model recently published [133], which uses virtual heat sources (VHS) at defect locations to model surface temperature data. In [133] between DC and ND were compared between the two models and experimental data, see Figure 43. It was found that while both models performed with a similar degree of accuracy when predicting the experimental data the VHS model over predicted the peak contrast whereas, the current model under predicted the peak contrast.…”

Section: Pulsed Thermography Model Resultsmentioning

confidence: 99%

See 2 more Smart Citations

Development of Infrared Techniques for Practical Defect Identification in Bonded Joints

Waugh

2016

Springer Theses

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Section: Pulsed Thermography Model Resultsmentioning

confidence: 79%

Section: Pulsed Thermography Model Resultsmentioning

confidence: 99%

Section: Pulsed Thermography Model Resultsmentioning

confidence: 99%

See 1 more Smart Citation

Development of Infrared Techniques for Practical Defect Identification in Bonded Joints

Waugh

2016

Springer Theses

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“…They are as follows: region of interest, digital filtering, automatic object counting and reporting, and fitting experimental data to a 1-D analytical model of physical behaviour. For complex material shapes or better accuracy, a 2-D model of heat conduction may be applied, as shown for example in Manohar and Lanza di Scalea (2013). Figure 2 shows a simplified version of the proposed data processing path with elements related to the task in bold type, i.e.…”

Section: Data Processing Pathmentioning

confidence: 99%

Determining the dimension of subsurface defects by active infrared thermography – experimental research

Gryś

2018

J. Sens. Sens. Syst.

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Abstract. This paper presents research into a method of processing thermal images aimed at detecting and characterizing material defects, or non-uniformities, of the internal structure of materials. Active thermography was chosen as the NDT method. Hidden defects were revealed by analysing the temperature field of the tested material's front surface which was externally excited with heating lamps. Background removal and image segmentation were applied to the last thermogram in the sequence recorded at the end of the heating phase. The paper focuses on the quality of determining lateral dimensions of subsurface flaws in a polymethylmethacrylate slab with bottom holes drilled to imitate flaws. The following accuracy-affecting factors were taken into account: defect depth, emissivity of the inspected surface as an input, user-set parameter for the IR camera, type of filtering used to eliminate the effect of non-uniformity when heating the object surface with an external source, and global and local thresholding as a segmentation method used for defect detection and sizing.

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“…Finite element approaches have been used previously to model pulsed thermography. In [13] carbon-carbon composites with voids are considered and in [14] steel plates with flat bottom holes are considered by using a secondary heat source as the defect in the FEA. Both models are developed for a specific experimental set up and only a single test case is shown.…”

Section: Introductionmentioning

confidence: 99%

Modelling and evaluation of pulsed and pulse phase thermography through application of composite and metallic case studies

Waugh

Dulieu-Barton

Quinn

2014

NDT & E International

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Results show PPT to be advantageous over PT due to its deeper probing as it is less influenced by surface features. Whilst UT is able to reveal all the defects in these case studies, the time consuming nature of the process is a significant disadvantage compared to the full field thermography methods. Overall, the model has achieved good correlation for the case studies considered and it was found that the main limiting factor of the PT model accuracy was knowledge of thermal material properties such as conductivity and specific heat. Where these properties were accurately known the model performed very well in comparison with experimental results. PPT modelling performed less well due to the method of processing the PT data which aims to emphasise small differences. Hence inaccuracies in inputted values such as material properties have a much greater influence on the modelled PPT data. The model enables a better understanding of PT and PPT and provides a means of establishing the experimental set-up parameters required for different components, allowing the experimental technique to be appropriately tailored to more complex situations including bonded joints or structures where several materials are present.The paper ends with a section on defect detectability based on thermal diffusivity contrast between the defect and the bulk material. It shows that in aluminium, because of its higher conductivity, greater thermal contrast is achieved for small differences in diffusivity. Regions where the diffusivity ratio between defect and bulk materials was insufficient to provide thermal contrast for defect identification were found. PPT phase data is shown to reduce the extent of such regions increasing the detectability of defects.Effusivity is introduced as a means of determining the thermal contrast between the defect and non-defective areas and hence establishing the defect detectability.

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Determination of Defect Depth and Size Using Virtual Heat Sources in Pulsed Infrared Thermography

Cited by 22 publications

References 5 publications

Development of Infrared Techniques for Practical Defect Identification in Bonded Joints

Development of Infrared Techniques for Practical Defect Identification in Bonded Joints

Determining the dimension of subsurface defects by active infrared thermography – experimental research

Modelling and evaluation of pulsed and pulse phase thermography through application of composite and metallic case studies

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