Lysenko I. Information - diagnostic system of pulsed eddy current nondestructive testing for mechanical engineering products

The dissertation is devoted to the development of the information-diagnostic system of pulsed eddy current nondestructive control for mechanical engineering products. In this work, the processes in the circuits of the eddy current transducer in the pulsed excitation mode were analyzed and the conditions for the occurrence of damped harmonic oscillations were determined. It allowed proposing the use of signal's natural oscillation frequency and decrement as informative parameters of the eddy current transducer signal. The method of analysis and processing of the signal informational parameters of the eddy current transducer in the pulse excitation mode was developed in the work. The method is based on the determination of the signals proposed informational parameters through their amplitude and phase characteristics by using the Hilbert transformation. The use of exponential approximation for the amplitude characteristic and the linear trend for the phase characteristic of the eddy current transducer signal to increase the accuracy of the determination of the signal informational parameters is proposed. The determination errors of the natural oscillation frequency and decrement of the eddy current transducer signal were analyzed. It allowed determining the conditions for obtaining the minimum error of the determination of signal informative parameters and determining the eddy current transducer signal analysis optimal time, which significantly affects the testing results in the conditions of noise influence.