Design And Experimental Research Of Versatile Eddy Current Test System

With the rapid development of modern science and technology, Non-destructive testing(NDT) technology has become most technology for shipbuilding, aerospace, chemical, railway, steel, metallurgy and other industries indispensable basic technology, eddy current nondestructive testing technology(ENDT) is capable of high resolution playing a particular role among those NDT methods,. With the use of increasingly complex products, and increasingly urgent requirements for safety, ENDT became more and more important to ensure product quality and protect the safety of the powerful means.In this paper, based on the law of electromagnetic induction studies, theoretical analysis was described including the basic principles of eddy current nondestructive testing, different electrical conductivity, the magnetic permeability of the material or material defects cause changes in the impedance of the detection coil, as well as skin effect, the standard penetration depth, lift-off effect. Then primary test method was proposed to use eddy current sensor types characteristic impedance analysis method for the detection coil and eddy current sensor circuit structure, theoretical analysis and mathematical derivations, suitable parameters was also deduced mathematically.According to the theory of the parameters obtained, a ENDT test system was designed with eddy current impedance plane method. Lower cost machine can be used with detection sensor alone. The instrument has a simple operation, high integration, small size, low power consumption, and stable output, the portable setup can achieve many functions like data acquisition, conversion, computing, storage, display and so on. The smart detection sensor is self-developed and produced, special sensitivity for the non-ferrous metals testament.Experimental studies relative to this research has been carried out include three parts below: the eddy current testing probe experiments, non-ferrous metal conductivity measurement test, eddy current testing experiments. Eddy current sensor experiments validated the sensor has a high sensitivity, conductivity measurement experiments range from 0.65 MS/m to 58.0 MS/m. Secondly, conductivity measurement standard line setting, linearity and repeatability test, lift-off compensation, were completed, at last quantitative detection of surface and near surface defects and defect length measurement were also finished. Above all, the result shows our designs is high precision, feasibility, and good stability.This paper completed the design of eddy current nondestructive testing system, the system can be widely used to measure the conductivity of non-ferrous metals, sorting metal materials and surface, near surface flaw detection.