A one-dimensional approach towards edge crack detection and mapping using eddy current thermography

[Display omitted] •1D approach of eddy current thermography was presented and experimentally validated for crack detection applications.•It separates the electromagnetic heat generation from the heat propagation along the sample.•1D heat diffusion model was derived describing the temperature gradien...

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Bibliographic Details
Published in:Sensors and actuators. A. Physical. 2020-07, Vol.309, p.111999, Article 111999
Main Authors: Barakat, Natali, Mortadha, Jafar, Khan, Ali, Abu-Nabah, Bassam A., Hamdan, Mohammad O., Al-Said, Samer M.
Format: Article
Language:English
Subjects:
Aluminum base alloys
Coils
Crack detection
Crack propagation
Cracks
Diffusion
Eddy current testing
Eddy current thermography
Eddy currents
Edge cracks
Flaw detection
Heat conductivity
Heat diffusion
Heat generation
Heat transfer
Induction heating
Inspection
Mapping
Nondestructive testing
Steady state
Temperature gradients
Thermal conductivity
Thermography
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Summary:[Display omitted] •1D approach of eddy current thermography was presented and experimentally validated for crack detection applications.•It separates the electromagnetic heat generation from the heat propagation along the sample.•1D heat diffusion model was derived describing the temperature gradient along the sample in a quasi-steady-state condition.•Temperature gradient across a crack is significantly higher than that estimated over a crack-free material.•An accuracy ranging between 1 and 13% in edge-crack depth estimation was delivered. Eddy current thermography (ECT) is an emerging nondestructive evaluation (NDE) technique, which is used to detect defects in metallic components. In this study, a one-dimensional (1D) heat transfer approximation is delivered to detect, locate and size surface edge cracks in bar samples using a low-power ECT experimental setup. The induction of eddy current heat generation function on one side of the sample delivers a quasi-one-dimensional heat transfer model where heat only propagates along the sample. The presented model takes into consideration convection heat transfer losses along the sample. It is demonstrated that convection heat transfer losses are considered negligible as heat propagates along a relatively high thermal conductivity metallic material such as aluminum alloys. This leads to an approximately uniform temperature gradient in a quasi-steady-state heat transfer condition along a crack-free sample. The presence of an edge crack alters the heat propagation near the crack. Accordingly, estimating the temperature gradient along a sample at a quasi-steady-state condition allows the detection and sizing of edge cracks far from the ECT excitation coil. Applying the proposed ECT inspection technique to detect edge cracks in aluminum alloys delivered an accuracy of 13 % in crack depth estimation.
ISSN:0924-4247
1873-3069
DOI:10.1016/j.sna.2020.111999