Cao Xiong, Li Erlong, Yuan Zilan, Zheng Kaituo
School of Mechanical Engineering, Sichuan University, Chengdu 610065, China.
Micromachines (Basel). 2024 Jun 11;15(6):775. doi: 10.3390/mi15060775.
The electromagnetic eddy current non-destructive testing system enables the non-destructive analysis of surface defect information on tested materials. Based on the principles of eddy current detection, this paper presents a digital eddy current detection method using high-speed sampling based on STM32. A differential eddy current coil is used as the detection probe, and the combination of a differential bridge and a differential amplifier circuit helps to reduce common-mode noise interference. The detection signal is collected via an STM32-based acquisition circuit and transmitted to the host computer through Ethernet for digital demodulation processing. The host computer performs operations such as smoothing averaging, sinusoidal fitting, and outlier removal to extract the amplitude and phase of the detection signal. The system also visually displays the condition of the tested object's surface in real time through graphical visualization. Testing showed that this system can operate at frequencies up to 8.84 MHz and clearly identify defects as narrow as 1 mm on the surface of the tested steel plate.
电磁涡流无损检测系统能够对被检测材料的表面缺陷信息进行无损分析。基于涡流检测原理，本文提出了一种基于STM32的高速采样数字涡流检测方法。采用差分涡流线圈作为检测探头，差分电桥与差分放大电路相结合有助于降低共模噪声干扰。检测信号通过基于STM32的采集电路进行采集，并通过以太网传输到主机进行数字解调处理。主机进行平滑平均、正弦拟合和异常值去除等操作，以提取检测信号的幅度和相位。该系统还通过图形可视化实时直观地显示被检测物体表面的状况。测试表明，该系统能够在高达8.84 MHz的频率下运行，并能清晰地识别被测钢板表面窄至1 mm的缺陷。
