The Design And Research Of Pulsed Eddy Current Defect Testing System

Most of the modern equipment work under the environment of high temperature and high pressure, while most of its components are made of steel. If these parts appear cracks and other defects in the operation, it will reduce the quality and safety of equipment operation, therefore, Non—destructive Testing(NDT) of equipment at regular intervals is the way to ensure the safe operation of the equipment. Because of its defects in metal structure of quantitative evaluation and nondestructive has incomparable advantage, the pulsed eddy current(PEC) testing technology has become the main focus of the nondestructive testing of metallic materials. The whole thesis, which based on studying and analysis the principle and the related technical method of the pulsed eddy current testing technology, designs a set of pulsed eddy current testing experimental platform. The main content of this paper is as follows:Firstly, study and analysis the principle and theoretical basis of pulsed eddy current testing system, as to provide the theoretical basis for the design of pulsed eddy current testing system.Secondly, propose the design scheme of pulsed eddy current testing system, then with the single chip processor as the core of the pulse signal generator is designed, as well as related power amplifier circuit, signal conditioning circuit(amplifying and filtering circuit) set up. Study the design method of cylindrical probe, including the excitation coil size, number of turns, inductance, resistance calculations and detection component selection, and produce a cylindrical probe.Thirdly, select data acquisition card, and write the detection signal acquisition, display, storage procedures in the Lab VIEW environment, import collected data into Matlab to filtering and curve fitting, achieve detection signal smoothing and noise reduction.Fourthly, use the experimental platform on corrosion-resistant steel sheet width ZGCr26 different depths crack defect detection test, and values using the peak voltage, voltage detection signal of the differential and the voltage difference rate of change characteristic to indentify the crack defect, the experimental results show that the platform has good feasibility.