U型脉冲漏磁传感器的检测仿真与试验研究

发布时间：2018-03-12 13:08

本文选题：铁磁性构件　切入点：脉冲漏磁　出处：《江南大学》2017年硕士论文　论文类型：学位论文

【摘要】：瞬态式漏磁检测技术针对导磁构件的电磁无损检测有着重要的应用前景,具有响应速度快、检测灵敏度高、易检测和易评估等优点,对铁磁性材料的探伤和评估有着重要的研究价值。本文以国内外漏磁检测技术的研究动态为基础,采用有限元仿真和实验验证相结合的研究方法,针对铁磁性构件的脉冲漏磁检测技术中传感器的结构设计、参数优化、缺陷检测、应力评估等方面开展了系统且深入的研究,研究的主要内容如下:首先,分析脉冲漏磁检测技术的检测机理。基于电磁学的理论基础,从磁感线的折射原理、漏磁场形成机理和漏磁检测机理三个方面进行分析,分析被测试件缺陷与电磁场之间的交互作用下漏磁场的大小和分布,根据响应信号的结果对缺陷进行特征值的提取以及对检测对象进行定量评估。其次,铁磁性构件脉冲漏磁检测有限元仿真研究。基于对脉冲漏磁检测机理的分析,采用有限元仿真的方法对U型脉冲漏磁传感器进行建模,对U型传感器进行优化设计,对比分析U型传感器激励方式、激励线圈结构参数、传感器提离高度以及U型磁轭结构尺寸的仿真结果,获得了具有较高灵敏度的U型传感器结构;仿真分析了不同深度的表面缺陷和下表面缺陷下U型探头与试件之间的磁场分布,提出铁磁性构件表面缺陷存在漏磁,而下表面缺陷主要体现在脉冲磁阻的变化规律;为进一步提高脉冲漏磁检测缺陷时三个方向漏磁场分量的检测灵敏度,基于脉冲漏磁和脉冲涡流的检测原理,提出了脉冲聚磁检测方法,仿真对比了脉冲漏磁和脉冲聚磁两种方式的检测精度,分析了新型检测方法的可行性;对铁磁性试件内部电导率和磁导率的变化规律进行仿真分析,提取可表征试件内部电导率和磁导率变化的特征值,为脉冲漏磁检测方式应用于应力检测的定量评估提供了理论基础。最后,铁磁性构件脉冲漏磁检测实验研究。为证明有限元仿真结果中总结得出的关于铁磁性试件的脉冲漏磁检测机理的准确性和可靠性,设计相应的脉冲漏磁检测实验系统并选取合适的响应信号降噪滤波处理方式,实验验证了仿真结果中提出的脉冲漏磁与脉冲磁阻相融合的检测方法的可行性,可用于实现铁磁性构件表面和下表面缺陷的检测和评估;对脉冲聚磁检测方法和脉冲漏磁检测方法进行实验对比分析,验证了新型脉冲聚磁检测方法的可行性;实验验证了脉冲电磁响应差分信号与铁磁性试件所受拉伸应力之间的变化关系,建立了脉冲漏磁检测应力的检测机制。
[Abstract]:Transient magnetic flux leakage detection technology has an important application prospect for electromagnetic nondestructive testing of magnetic conductivity components. It has the advantages of fast response speed, high detection sensitivity, easy detection and easy evaluation, etc. It has important research value for flaw detection and evaluation of ferromagnetic materials. Based on the research trends of magnetic flux leakage detection technology at home and abroad, the research method of finite element simulation and experimental verification is adopted in this paper. The structure design, parameter optimization, defect detection and stress assessment of the sensor in the pulsed magnetic leakage detection technology of ferromagnetic components are studied systematically and deeply. The main contents of the research are as follows: firstly, Based on the theory of electromagnetism, the principle of magnetic inductance line refraction, the formation mechanism of magnetic field leakage and the mechanism of magnetic leakage detection are analyzed. The size and distribution of leakage magnetic field under the interaction between defect and electromagnetic field are analyzed, the characteristic value of defect is extracted according to the result of response signal, and the detection object is quantitatively evaluated. Based on the analysis of the mechanism of pulsed magnetic leakage detection, the finite element simulation method is used to model the U type pulsed magnetic leakage sensor and to optimize the design of the U type sensor. The simulation results of the excitation mode, the structure parameters of the excitation coil, the lift height of the sensor and the size of the U-type magnetic yoke structure are compared and analyzed, and the U-type sensor structure with high sensitivity is obtained. The magnetic field distribution between U-shaped probe and specimen under different depth surface defects and lower surface defects is analyzed. It is proposed that magnetic leakage exists on the surface defects of ferromagnetic components, while the lower surface defects are mainly reflected in the variation law of pulse magnetoresistance. In order to improve the detection sensitivity of magnetic flux leakage components in three directions when detecting defects with pulse magnetic flux leakage, based on the detection principle of pulse magnetic flux leakage and pulse eddy current, a method of pulse magnetic field accumulation detection is proposed. The accuracy of pulsed magnetic flux leakage and pulse magnetic accumulation is compared, and the feasibility of the new method is analyzed, and the variation of internal conductivity and permeability of ferromagnetic specimen is simulated and analyzed. The characteristic values which can characterize the change of internal conductivity and permeability of the specimen are extracted, which provides a theoretical basis for the application of pulsed magnetic flux leakage (PMST) in quantitative evaluation of stress measurement. Experimental study on Pulsed Magnetic leakage Detection of ferromagnetic components. In order to prove the accuracy and reliability of the mechanism of pulsed magnetic leakage testing for ferromagnetic specimens summarized in the finite element simulation results, The corresponding experimental system of pulse magnetic flux leakage detection is designed and the appropriate noise reduction filter processing method of response signal is selected. The feasibility of detecting method of pulse magnetic flux leakage and pulse magnetoresistive fusion proposed in the simulation results is verified by the experiment. It can be used to detect and evaluate the surface and lower surface defects of ferromagnetic components. The relationship between the difference signal of pulse electromagnetic response and the tensile stress of ferromagnetic specimen is verified and the detection mechanism of pulsed magnetic leakage detection stress is established.
【学位授予单位】：江南大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM271;TP212

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