| NDT is no damage to structures in the performance and integrity of the detection of some physical properties of metal components and organization of the state, and to identify a variety of building and internal defects in metal surface technology. Pulsed eddy current detection method is an electromagnetic non-destructive testing, it does not require coupling medium, non-polluting, spectrum width, detection speed, sometimes sub-surface defects in the layer of the quantitative detection and assessment of the potential advantage has been shown by researchers attention.However, due to the presence of skin effect, pulsed eddy current technology can only be accurately reflected within 5mm from the detection of surface defects, which become thicker conductor pulsed eddy current detection of deep defects in the bottleneck. This careful consideration the impact of pulsed eddy current penetration depth factor, to enhance the excitation current has been demonstrated for the breakthrough and make experiments.System uses low-voltage power supply means chopping a large current pulse.10mm thick steel plate used in the processing of different sizes to simulate steel rectangular tank cracks. Design of cylindrical steel probe surface and near surface testing by way of exciting coil slowly discharge; design rectangular plate sub-surface probe testing by way of exciting coil instantaneous discharge. Posed by two differential input Hall sensor, and zoom in with the AD620 instrumentation amplifier. The filtered signal with the data acquisition card, the pulsed eddy current signal wavelet filter noise and normalized for analysis. The LabView platform synchronized sampling method using real-time scan detection plate. Correctly reflect the measurement data can identify high-current incentive thick steel plate testing, system performance and stability, anti-interference ability, to complete the intended research objectives.
|
PDF Full Text Request