Emissivity Correction and Thermal Pattern Reconstruction in Eddy Current Pulsed Thermography

Area of Science:

• Materials Science and Engineering
• Non-Destructive Testing and Evaluation (NDT&E)
• Infrared Thermography

Background:

• Emissivity variations pose a significant challenge in thermography, impacting temperature accuracy.
• Accurate temperature calculation in infrared thermography relies heavily on correct emissivity settings.
• Eddy current pulsed thermography (ECPT) is sensitive to surface emissivity variations.

Purpose of the Study:

• To develop and validate an emissivity correction and thermal pattern reconstruction technique for ECPT.
• To improve the detectability of material defects and characterization without emissivity interference.
• To enhance the efficiency of high-speed NDT&E for applications like rolling stock.

Main Methods:

• A novel emissivity correction algorithm based on physical process modeling and thermal feature extraction.
• Thermal pattern correction using averaged normalization of thermal features in both spatial and time domains.
• Experimental validation on heat-treated steels for case-depth evaluation and gear defect analysis (failures, fatigue).

Main Results:

• Successfully corrected thermal patterns by mitigating emissivity variations.
• Enhanced detectability of faults and improved material characterization.
• Demonstrated effectiveness in experimental studies involving critical components for rolling stock.

Conclusions:

• The proposed technique effectively addresses emissivity challenges in ECPT.
• The method significantly improves defect detection and material characterization capabilities.
• The technique offers enhanced inspection efficiency for high-speed NDT&E, particularly in rolling stock applications.