Abstract
Microcracks are a common metallic defect, resulting in degradation of material properties. In this paper, specimens with different fatigue microcracks were detected by eddy current pulsed thermography (ECPT). Signal processing algorithms were investigated to improve the detectability and sensitivity; principal component analysis (PCA) and Tucker decomposition were used to compare the performance of microcrack detection. It was found that both algorithms were highly adaptable. A thermal quotient was used to assess the temperature variation trend. Furthermore, the potential correspondence between crack closure and temperature change was investigated.
Highlights
In recent years, infrared (IR) technology has been successfully applied to power, rail, and other fields because of its advantages for noncontact, high sensitivity, and visualization [1,2,3,4]
Tong et al [10] modified the modelling of eddy current pulsed thermography (ECPT) to achieve quantitative evaluation of blade surface fatigue cracks in heavy-duty gas turbines
We aim to examine applications of ECPT in fatigue microcrack in a more comprehensive way
Summary
In recent years, infrared (IR) technology has been successfully applied to power, rail, and other fields because of its advantages for noncontact, high sensitivity, and visualization [1,2,3,4]. Eddy current pulsed thermography (ECPT) uses external high-frequency alternating current to excite the detection coil so as to generate heat on the surface or the inside of the measured specimen [5]. Several results based on ECPT in the fields of crack detection have been reported. Vrana et al [7] proposed simplified models for crack detection with induction thermography. Shi et al [8] proposed a quantitative crack detection method, and cracks of different sizes were analysed. Weekes et al [9] performed an experimental investigation of fatigue cracks in steel, titanium, and nickel-based superalloy, and results of probability of detection (POD) were established. Genest and Li [13] used both experimental and numerical assessments of the induction thermography technique, detecting the microcrack in notched steel coupons
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