A Method To Detect And Quantitate Flaw With Pulsed Eddy Current Technology Considering Temperature Drift Effect

Pulsed Eddy Current Nondestructive testing, as a widely used electromagnetic testing technology, plays an important role in the remanufacturing process of used metallic parts. However, the temperature drift effect caused by temperature-rise of exciting coil during testing process will have a great negative influence on the precision of PEC testing. In terms of this problem, a new method to quantitate flaw depth with pulsed eddy current testing technology considering temperature drift effect and its practical application are investigated in this paper.Firstly, the research significance of this topic, the researching status at home and abroad and the basic theory of Pulsed Eddy Current testing technology are expounded, also the equivalent circuit model is built as well. Then, the temperature drift effect on the output of PEC probe is analyzed through theoretical method based on the equivalent model above.To further research on the temperature drift effect of exciting coil of PEC probe, a new type of pulsed eddy current probe, equipped with temperature sensor, is specifically designed. Also, combined with the structure of this new kind of PEC probe, a set of fully functional Pulsed Eddy Current testing hardware platform and data-analyzing software platform based on LabVIEW are developed and implemented correspondingly.Then, a new feature of testing signal called "RMS of single hall's output voltage" is proposed, and the quantitative characterization of depth of surface defects is implemented using this new characteristic of PEC testing signal. At the same time, after the complete analysis of temperature drift effect,caused by temperature rise of exciting coil, on the output of PEC probe, in theoretical and experimental way, an automatic temperature compensation method based on the new probe is brought up based on the new designed probe. The temperature drift compensation algorithm for the probe can be processed and achieved automatically in the LabVIEW software platform after programming. And the correctness and feasibility of this temperature compensation method is verified through the analysis of experimental results.