GMR传感器在无损检测中的研究与应用

发布时间：2018-08-01 17:20

【摘要】：在飞机、船舶、汽车等建造工业领域生产中,无损检测作为其关键部位零器件缺损情况检测最重要的手段之一,无损检测技术在探测关键部位零器件缺陷、消除潜在的安全隐患、保障设备的安全运行等方面发挥着极其重要的作用。其中,如何提高检测精度是目前亟需解决的一大难题。本文将以此为背景,应用无损电涡流检测原理,引入高灵敏度的巨磁电阻(GMR)芯片,设计了一款新型的无损探测系统。本文首先对电涡流探头的结构进行了研究,传统的线圈式探头其灵敏度随着工作频率的降低而减少,现有的基于传感器芯片的电涡流探头,内部采用一个单一的激励线圈,当通入交流电时激发的磁场会对涡流信号造成干扰,进而影响缺陷检测。鉴于此,本文对探头的结构作了改进即在激励线圈的基础上再额外增加一个消除线圈,以此降低激励场对涡流信号的干扰,从而提高检测精度。本文利用有限元软件ANSOFT MAXWELL模拟仿真了一个无损检测模型,在其中涡流检测探头的结构上增加了一个消除线圈,通过仿真结果得出:相比于常规式只有单一激励线圈的探头,新型的GMR探头采用了双线圈,且线圈中心芯片放置处磁场变化量更大而周围磁场较弱。随后实物制作了这款具有高信噪比的巨磁电阻(GMR)电涡流探头。其次本文还针对新型的探头设计并改进了一个无损检测系统,系统设计主要分为硬件电路和软件两个部分,其中硬件电路设计主要有正弦波发生电路、功率放大电路以及信号调理电路。正弦波发生电路采用单片机控制DDS芯片的方式来产生一定频率的正弦波,信号调理电路则采用锁相放大、放大和低通滤波的方式对探头的原始输出信号作相应的调理;软件方面集中在单片机编程控制芯片产生正弦波和后续数据处理上利用数据采集卡和LABVIEW编程实现数据信息的实时处理和观测。通过后期PCB板的调试,系统中各模块能发挥各自良好的功能。最后对以上所设计的无损检测系统进行了试件缺陷检测,通过多组实验数据的对比得出结论:新型结构的GMR探头能够检测试件中的缺陷并且检测精度较高。
[Abstract]:Nondestructive testing (NDT) is one of the most important methods to detect the defect of zero devices in the key parts of aircraft, ships, automobiles and other construction industries, and the technology of nondestructive testing is used to detect the defects of zero devices in the key parts. Eliminating potential hidden dangers and ensuring the safe operation of equipment play an extremely important role. Among them, how to improve the detection accuracy is a big problem that needs to be solved. In this paper, a new nondestructive detection system is designed based on the principle of nondestructive eddy current testing and the introduction of a high sensitivity Giant Magnetoresistance (GMR) (GMR) chip. In this paper, the structure of the eddy current probe is studied. The sensitivity of the traditional coil probe decreases with the decrease of the working frequency. A single exciting coil is used in the existing eddy current probe based on the sensor chip. The magnetic field excited by the AC current will interfere with the eddy current signal and affect the defect detection. In view of this, the structure of the probe is improved, that is, an additional elimination coil is added on the basis of the exciting coil to reduce the disturbance of the excitation field to the eddy current signal, thus improving the detection accuracy. In this paper, a nondestructive testing model is simulated by using the finite element software ANSOFT MAXWELL, in which an elimination coil is added to the structure of the eddy current detection probe. The simulation results show that compared with the conventional probe with only a single excitation coil, The new GMR probe uses double coils, and the magnetic field in the central chip of the coil is much larger and the magnetic field around it is weaker. Subsequently, the GMR (GMR) eddy current probe with high signal-to-noise ratio was fabricated. Secondly, this paper also designs and improves a nondestructive testing system for the new probe. The system design is mainly divided into two parts: hardware circuit and software, in which the hardware circuit design mainly includes sine wave generation circuit. Power amplifier circuit and signal conditioning circuit. The sinusoidal wave generating circuit uses the single chip computer to control the DDS chip to produce the sine wave of a certain frequency, and the signal conditioning circuit uses the phase-locked amplification, amplification and low-pass filter to adjust the original output signal of the probe. The software is focused on the sine wave generation and subsequent data processing on the single chip microcomputer programming control chip. The data acquisition card and LABVIEW program are used to realize the real-time processing and observation of the data information. Through the later debugging of PCB board, each module in the system can play its own good function. Finally, the defect detection of the NDT system designed above is carried out, and the conclusion is drawn through the comparison of many groups of experimental data: the new structure GMR probe can detect the defects in the specimen and the detection accuracy is high.
【学位授予单位】：电子科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TP212;TP274

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