Application Cases

Experiment Name: Application of Power Amplifier in Simulation Research of Pulsed Eddy Current Magnetic Field Gradient Detection Method

Experimental Equipment: Signal generator, power amplifier ATA-4011, differential amplifier, filter, data acquisition and processing unit, probe, etc.

Experiment Objective:
Currently, most three-dimensional numerical simulations of pulsed eddy current testing rely on commercial finite element software, which often demands high computer performance and lengthy simulation computation times. In light of this, this study adopts a pulsed eddy current testing finite element calculation method based on the reduced magnetic vector potential approach. A three-dimensional simulation model for detecting interlayer corrosion defects in multilayer metal structures using the pulsed eddy current magnetic field gradient method is established.

Experimental Procedure:
The pulsed eddy current magnetic field gradient testing system mainly consists of a signal generator, power amplifier, differential amplifier, filter, data acquisition and processing unit, probe, and test specimen. The signal generator is used to generate a square wave excitation signal. The power amplifier amplifies the excitation signal to drive the probe. The differential amplifier amplifies the acquired detection signals (magnetic field gradient signal and magnetic field signal). Since the noise in the detection signal is mainly concentrated in the high-frequency range, a low-pass filter is used to filter the signal. The data acquisition card is used for data acquisition of the preprocessed signals. A LabVIEW program is used to display the detection signals in real time, extract signal peaks, and obtain defect scan curves.

The detection probe consists of a disc-type excitation coil and two Hall sensors. The excitation coil has an inner diameter of 10 mm, an outer diameter of 15 mm, a height of 20 mm, and 1500 turns. The two Hall sensors are placed at different heights along the central axis of the excitation coil. The magnetic field gradient signal is obtained by dividing the difference between the magnetic field signals picked up by the two sensors by the height difference between them.

Figure: Schematic Diagram of the Simulation Model

Experimental Results:
From the imaging results, it can be seen that the imaging of interlayer corrosion defects based on the pulsed eddy current magnetic field gradient method can describe the defect contour more effectively. This conclusion is consistent with the simulation analysis results. Both simulation and experimental studies indicate that the pulsed eddy current magnetic field gradient detection method can achieve high-precision imaging of interlayer corrosion defects in multilayer metal structures.

Figure: Measured Waveform of the Magnetic Field Gradient Signal

Figure: Measured Waveform of the Magnetic Field Signal

Figure: Defect Imaging Using the Magnetic Field Gradient Signal

Figure: Defect Imaging Using the Magnetic Field Signal

Figure: Specifications of the ATA-4011C High-Voltage Power Amplifier