| Pulsed eddy current testing has been widely used in industrial detection. It has won the favor of testing person, because the equipment is simple, easy to operate, less susceptible to interference, faster detection speed, non-contact and other advantages.Based on the principles of pulsed eddy current testing, this paper use finite element software COMSOL to do the size optimization of the detection probe, and research the influence about changes of material’s electrical conductivity and magnetic permeability. Designed a pulsed eddy current testing system to study the law of crack defects of ferromagnetic material surface. The system include sensors, a signal generator, power amplifier electronics, data acquisition card, a electric circuit for signal conditioning and a computer, and the sensor is made of a cylindrical excitation coil on a ferrite and a Hall sensor. The experimental platform is based on MATLAB software for signal acquisition and analysis, the subject successively use PWM Pulse and SPWM Pulse to study the defects of specimens, using synchronous sampling method to achieve pulsed eddy current response signal by DAQ card.With extracting the peak voltage of defects, the spectral characteristics of the specimen for processing and analysis by MATLAB software. According to the relationship between the above-described various defects of the curve, to give detect assessment.The research show that: The wide flat type probe can detect iron magnetic material effectively; the influence of different incentive wave parameters on pulse detection; the influence of modulated wave frequency of SPWM pulse on detection. This study successfully find a new way on pulsed eddy current testing methods, and make a experimentally verification on the suppose. |
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