A Novel Methodology to Predict 3-D Surface Temperature Field on Delamination for Thermography

This article proposes a novel 3-D surface temperature prediction model based on the restored pseudoheat flux (RPHF) theory. The method can be used to simulate the temperature difference between the subsurface defect and the sound area. The proposed model shows the potential to investigate the detection limits associated with the defect features, such as depth, radius, diameter-to-depth ratio (D2dR), and excitation features, which is beneficial for the experimental design. Several experiments were conducted on specimens of different materials [glass fiber reinforced plastic (GFRP), CFRP, and rubber] using RPHF thermography to validate the practicality of the model. The comparative analysis is also conducted with other methods. Both experimental and simulation results demonstrated that longer heating is required for deeper defects and the moment of maximum temperature difference tends to appear after the heating has stopped. Probability of detection (PoD) was used as an index to assess the reliability of the methodology and the problems found. The depth of the defect has a greater influence on thermal detection than D2dR.