Study And Modeling Of Infrared Nondestructive Testing System

Infrared Thermography Non-destructive Testing (ITNDT) is a new developed technology. It can detect the cracks, debondings in metal, non-metallic and composite material and is non-contact, detection area, high speed, on-line detection and so on. But now the research in China is still in its infancy and research phase. The established testing system depends on domestic equipment much less than imported. So the development cost of infrared non-destructive testing equipment is high, and the research and application of this technology is difficult to promote. According to this, the equipment is research independently, and can achieve the purpose of nondestructive testing. Compared with some equipment from abroad, it is simple structure, low cost, convenience, etc.This paper studied its fundamental theories, including one dimensional heat conduction and infrared thermal radiation theory. Based on that the relevant algorithm model of information processing is established, and the size, shape and other information of internal defects are determined by extracting the thermal wave signal phase information.According to the phase principle of NDT localization testing equipment was established. Firstly, the incentive light source system modulated as sine was designed. It can heat the target periodically and initiatively. Secondly, a domestic uncooled focal plane array infrared thermal imager named CCTC-0504 was used to record the surface thermal wave signal of target. Thirdly, the special image processing software system is coded with the high-level language Visual C++. The software can mainly extract most information of the defects. Finally, the test of A3 steel sample with different shape and depth of defects was done, and it proved that the equipment developed in this paper can detect the shape and size of interior defects effectually. Through the analysis and contrast of the test result, it demonstrated that the frequency and duration of modulated incentive system and the depth of defects all affect the test effect in different degree. The development of this system improved the problem that domestic non-destructive testing system relies on imported equipment, and it provided an effective means for research and application of infrared non-destructive testing technology in the future.