Physical Model Study on Subsurface Defects Detection in Eddy Current Pulsed Thermography

Eddy current pulsed thermography (ECPT) combines the efficiency of eddy current pulsed technology with the high resolution of thermal imaging technology, has been found widespread application in non-destructive testing (NDT). However, most of the current algorithms and models primarily rely on one-dimensional heat conduction on vertical direction, which exhibit lower capabilities in modeling transverse heat transfer. Because of the significant impact of the lateral heat transfer in subsurface defect detection, we propose a discretized three-dimensional thermal diffusion model based on ECPT, which enables the simulation of the thermal diffusion process following ECPT excitation. We analyzed the thermal diffusion states and its causes at different defect burial depths and times, and set up an ECPT experimental platform to collect experimental data. Experimental results indicate that this model can effectively simulate the thermal diffusion process within acceptable margins of error (less than 0.4%), which shows great potential in the application of ECPT in subsurface defect detection.