Infrared Thermal Wave Nondestructive Determination Of Defect Size Detection Technology

Infrared thermal wave nondestructive method is based on the thermal wave theory, using different heat source heat the detected material, different medium material's surface and subsurface physical properties and boundary conditions will change the thermal wave's conduction, and then the change will be shown on the surface's temperature field. Through the measure of the surface temperature field, we get the information about the material and the subsurface structure to attain the object of nondestructive testing.The work in this paper is through analyzing the simulated defect samples made of aluminum and fiber glass to discuss the way to measure the sizes of samples. The flat bottom hole samples and flume samples are designed to do the different depths and sizes measurement.The work includes two ways to do the measure: one is to seek the optimal threshold of the difference of defect and nondefect areas and use the threshold to measure the size of defects. The other is to fit the experimental data based on the theory. The results show that defects with big size and shallow depth can well be measured by the two ways, while there are errors for the measure of the defects with deep depth or/and small size.