Eddy Current Thermography Defect Reconstruction via Electrical Impedance Tomography
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Solution Overview
Problem
Existing eddy current thermography methods can only detect the location of defects in metal materials but cannot quantify the defect profile, which is crucial for preventing disasters in industries like aerospace and high-speed railway.
Innovation Solution
A method combining eddy current thermography with electrical impedance tomography to reconstruct the conductivity distribution from thermogram sequences, allowing for the identification of the true defect profile by leveraging the significant difference in conductivity between defect and non-defect regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional eddy current thermography method is used to detect defects, then the location of defects can be identified through high temperature regions in thermograms, but the true profile of the defect cannot be obtained because high temperature only exists in the two ends of the defect
Solution Approach 1:
The patent transforms the detection parameter from temperature distribution to conductivity distribution. By using electrical impedance tomography to reconstruct the conductivity distribution from thermogram sequences, the method can identify the true defect profile based on the significant difference in conductivity between defect and non-defect regions, rather than relying on temperature gradients that only show defect locations
Solution Approach 2:
The patent introduces conductivity distribution as an intermediary parameter between the measured temperature field and the actual defect profile. The electrical impedance tomography technique uses the thermogram sequences as input to reconstruct the conductivity distribution, which then serves as a bridge to accurately identify the defect profile, overcoming the limitation of direct temperature-based detection
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables the quantification of defect profiles, providing more accurate and detailed information about defects compared to traditional methods, which can enhance safety and reduce the risk of accidents.
Implementation Method 1
Coil with high frequency alternating current can generate an electromagnetic (EM) field. When the electromagnetic field is applied to a conductive material, an induced eddy current will be generated.
Implementation Method 2
When a defect exists in the conductive material, eddy current (EC) will come together at the defect region, then a high temperature region will emerge.
Data Source
AI summary
The present invention provides a method for eddy current thermography defect reconstruction based on electrical impedance tomography, first, obtaining a thermal reference image of temperature change with time by acquiring a thermogram sequence S of the specimen in the process of heating and fitting a curve for pixels of each location of the thermogram sequence S, then, creating a current matrix and a magnetic potential matrix, and calculating the satisfied conductivity distribution through iterations, so as a reconstructed image is obtained, then taking the low conductivity area of the reconstructed image as the defect profile, thus the defect profile is identified and quantified.