| Electromagnetic ultrasonic technique has become one of the important means of detection in industrial production. Because it not only can detect objects without contact or moving objects in various environments, but also can produce a variety of waveforms. Thickness measurement is an important indicator of object detection, especially in the metal plate detection, it is essential to ensure quality and safety of plate.This article studies the electromagnetic ultrasonic metal plate thickness measurement from the experimental and theoretical aspects, and processing the signal collected using software. In theory, this paper studies the basic principle of electromagnetic ultrasonic detection, select transverse wave as the wave type and the transducer structure is determined. The simulation is established using finite element software. For non-ferromag- netic material, the force and displacement of specimen suffered can be obtained from the electromagnetic structure coupling analysis. The analysis shows the main transmission angle. Simulation analyzes the effect on particle displacement by changing frequency, spaced coil and coil lift-off. For the ferromagnetic material, paper introduces an analogy method between magnetic analysis and piezoelectric analysis. In experiment, aluminum plate is measured using the electromagnetic ultrasonic testing platform and the results show that the theoretical analysis is content. In this paper, the weak signal collected with noise and interference is filtered. Comparing to the principle and characteristics of different processing algorithms, this paper chose the average algorithm and wavelet algorithm. The results show that, after processing the signal is improved.The experiment system of thickness measurement is set up and it is used to detect plate. The experiment results can verify the theoretical analysis and simulation effectively, and can measure thickness of metal plate. |
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