【作者】 李文艳；

【导师】 黄东升； 陈国明；

【作者基本信息】 中国石油大学 ， 机械工程， 2010， 硕士

【摘要】 本文结合山东省科技发展计划项目:ACFM缺陷智能可视化检测系统开发及工业应用(2007GG10005004),建立ACFM缺陷定量分析的数学模型并开发出ACFM检测系统工业样机。在电磁-电路耦合仿真分析、ACFM缺陷智能可视化探头系列化设计与优化、磁场信号软硬件处理技术、ACFM工业样机开发及应用和工业参数测试等方面均取得较大进展。主要内容及研究成果如下:(1) ACFM缺陷识别与数值仿真分析结合ACFM检测原理和数值计算理论,提出ACFM缺陷识别的数学模型以及裂纹深度的计算方法,并且引入电磁-电路耦合分析方法,对进行线性电路模拟的通用电路单元进行了分析,应用ANSYS对二维电磁-电路耦合进行仿真分析,更为准确地模拟了检测时感应电磁场的分布规律以及不同参数对检测结果影响,为以后的实验研究提供了理论依据。(2) ACFM探头的系列化设计对激励线圈的各个参数进行了数值仿真,得出参数及结构的变化对工件表面感应电磁场分布的影响规律,为探头的设计和优化提供理论依据。对探头总体结构进行设计,选择矩形激励线圈并合理设计检测线圈的尺寸。针对应用场合的不同,制作了标准单探头、曲面检测探头、笔式探头和阵列探头等多种类型的探头。标准单探头灵敏度较高,曲面检测探头用于检测具有一定曲率的工件,笔式探头主要用于空间狭窄的区域,而阵列探头其检测面积增大,提高了检测速率,降低了漏检率。利用各类探头对工件进行检测,实验结果表明探头具有较高的灵敏度。(3) ACFM检测系统工业样机开发以工业应用为目的,采用软硬件相结合的方法对交流电磁场检测系统进行设计和搭建。硬件方面设计了信号发生和信号调理电路,对信号进行初处理;然后采用数据采集卡进行A/D转换后输入由Labview软件编制的数字信号采集与处理模块。该系统可放大采集到的微弱信号并抑制噪声的干扰,简化了硬件电路,节约系统开发的成本,能够实现缺陷的实时判别和可视化检测,为工业应用和试验提供支持。(4) ACFM检测系统样机的工业应用对影响ACFM检测系统样机技术指标的一些重要参数进行了实验研究,结果表明该系统的不失真提离高度和不失真检测速度都较高,而且电缆长度在一定范围内对Bx影响较小但对Bz影响较大。利用该样机对无裂纹和含有轴向裂纹、径向裂纹和表面下裂纹的在役设备进行了检测,结果表明系统能够实现缺陷的实时判别和自动量化,准确的反演出缺陷的形状,具有较高的检测精度。更多还原

【Abstract】 This thesis focuses on the theoretical analysis of ACFM and the prototype development, including simulation analysis of magnetic-circuit couple, design and optimization for intelligent recognition and visualization probe, electromagnetic signals processing based on hardware and software, development and industrial application of ACFM prototype and so on, which is sponsored by Scientific and Technological Development Projects in shandong province (No.2007GG10005004). The main research progress is summarized as follows:(1) Theoretical research and numerical simulation analysis of ACFMCombined with principle of ACFM and theory of numerical calculation, mathematical model of ACFM defect recognition and calculation method of crack depth are presented. In order to analyze the distribution of electromagnetic field and the impact of various parameters on the results, simulation analysis of two-dimensional electromagnetic–circuit coupled is introduced and the common circuit elements that can be used for linear circuit simulation provided by ANSYS are introduced. All of this can provide theoretical basis for the future experimental research.(2) Series design of probeThe induced simulation model of inducer with different parameters is built based on ANSYS, and then discussed the relationship between parameters of the inducer and the induced electromagnetic field distribution. This provides the theoretical foundation to design and optimize the probe. To achieve better effect, overall structure of every kinds of sensor is designed including standard single probe, surface detection probe, pen probe and array probe that with reasonable size and shape of inducer coil. The application situation and environment of every kinds of probe are different. Standard single probe has high sensitivity which can be used in any situation, and surface inspection probe is mainly used for surface detection and pen probe can be used in the narrow zone. The array probe can increase the detection area and improve the detection rate. The results show that the probes have a high sensitivity when they are used to detect the workpiece.(3) Study on prototype for ACFMACFM system is set up for the purpose of industrial application, including design of hardware and software parts. Firstly, the primary signal process is realized by designing signal producing and processing circuits. Then, the analog signal is acquired by data acquisition card, which processed by digital signal acquisition and processing software modules compiled by Labview language. Considering the methods of combining hardware and software, system can amplify weak signals and suppress noise, this method simplifies hardware circuit and economizes the cost of system development. This system can achieve the visualization of the defect intelligent and visual recognition, which provides the foundation for industrial application and industrial test.(4) Industrial application of ACFM prototypeSome important industrial parameters that affect the technical index of ACFM prototype are tested, the results show that the system has a high detection speed and lift-off height without distortionless, and influence of cable length to Bx is small but greater than Bz in certain extent. Moreover, in-line equipment having crack-free, axial cracks, radial cracks and sub-surface cracks can also be detected by this system, the results show that system have a high detection accuracy, they can achieve real-time discrimination and intelligent quantifying recognition. In addition, the system can be more accurate in discription of defect shape.更多还原