Fig. 1. Experimental schematic of laser infrared thermal imaging detection. (a) Laser infrared thermal imaging test system; (b) laser excitation principle

Fig. 2. Experimental geometric model and experimental platform. (a) Geometric model and its temperature field distribution; (b) experimental platform

Fig. 3. Infrared thermal images of laser excitation point region of sample under different cooling time. (a) 4 s; (b) 8 s; (c) 12 s; (d) 16 s

Fig. 4. Temperature curves of model under different excitation time and temperature of each point on line between excitation point and defect center point. (a) Excitation time is 1 s; (b) excitation time is 2 s; (c) excitation time is 3 s; (d) temperature distribution of each point on line between excitation point and defect center point

Fig. 5. Comparison diagram of simulation results and experimental results at different locations. (a) Temperature contrast diagram of excitation point; (b) temperature contrast diagram of defect center point

Fig. 6. Simulation model and surface temperature curve. (a) Simulation model; (b) temperature curves at point A; (c) temperature curves at point B; (d) surface temperature difference curves

Fig. 7. Fitting curve of excitation time and maximum temperature difference

Table 1. TC4 material properties

Table 2. Conversion relationship between different excitation time and standard defect parameters