Three-dimensional subsurface defect shape reconstruction and visualisation by pulsed thermography

Adisorn Sirikham,Yifan Zhao,Haochen Liu,Yigeng Xu,Stewart Williams,Jörn Mehnen

doi:10.1016/j.infrared.2019.103151

Adisorn Sirikham, Yifan Zhao + Show 4 more

Open Access

https://doi.org/10.1016/j.infrared.2019.103151

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Abstract

Defects detected by most thermographic inspection are represented in the form of 2D image, which might limit the understanding of where the defects initiate and how they grow over time. This paper introduces a novel technique to rapidly estimate the defect depth and thickness simultaneously based on one single-side inspection. For the first time, defects are reconstructed and visualised in the form of a 3D image using cost-effective and rapid pulsed thermography technology. The feasibility and effectiveness of the proposed solution is demonstrated through inspecting a composite specimen and a steel specimen with semi-closed airgaps. For the composite specimen, this technique can deliver comparatively low averaged percentage error of the estimated total 3D defect volume of less than 10%.

Highlights

As a highly efficient and powerful non-destructive testing (NDT) technique, pulsed thermography (PT) offers a rapid, contact-free, highefficient inspection and shows promising applicability to in-situ monitoring applications [1,2,3,4]
This paper reports a new method of 3D reconstruction and visualisation of subsurface defect shape based on a single-side thermographic inspection
This paper has developed a novel 3D reconstruction and visualisation approach for subsurface defect based on one single-side PT inspection under the reflection mode

Summary

Introduction

As a highly efficient and powerful non-destructive testing (NDT) technique, pulsed thermography (PT) offers a rapid, contact-free, highefficient inspection and shows promising applicability to in-situ monitoring applications [1,2,3,4]. Absolute Peak Slope Time method (APST) [13] multiplies the square root of its time to temperature decay curve, and estimates the defect depth by the peak time of the first derivative curve. The Logarithm Second Derivative method (LSD) [14] estimates the defect depth by fitting the logarithmic second derivative of temperature decay curve using a polynomial model. In the area of nuclear and aerospace industries, 3D visualisation is reconstructed from the digital X-ray images and has been used to view the location, shape and size of the defects like corrosion, delamination and crack, and evaluate the thickness of walls in the object of titanium aerospace investment casting [22,23]. The X-ray technology is comparatively time consuming [24], comes with potential health risks [25] to the user and is typically limited with respect to the maximum size of the parts to be analysed [22,26,27,28,29]

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