【作者】 赵艳丽；

【导师】 何新霞；

【作者基本信息】 中国石油大学 ， 检测技术与自动化装置， 2009， 硕士

【摘要】 交流电磁场测量(ACFM)技术是近年来兴起的一种新型电磁无损检测技术,该方法不受提离效应、材料属性、边缘效应的影响,对结构物表面裂纹可实现长度和深度的定量测量。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”的相关研究内容,通过理论分析和实验研究,对ACFM检测信号的处理方法及应用进行了较系统的研究。对交流电磁场检测的数学模型进行探讨,利用有限元数值仿真方法,采用远场域处理三维电磁场中开域问题的方法,建立矩形和u型ACFM激励探头模型及ACFM有限元模型,对受缺陷扰动的磁场分布状态进行研究。实验验证仿真结论的正确性,为表面缺陷的定量测量提供了理论基础。设计满足空间“点”磁场测量的检测线圈尺寸,研制基于矩形、U型磁芯及单个、阵列检测线圈的系列化探头。在此基础上,设计激励信号源与信号调理电路。应用面向对象的编程思想,编制基于虚拟仪器的系统检测软件。利用数字滤波、小波分析等现代信号处理技术,结合Labview与Matlab混合编程的方法,对检测到的微弱信号进行消噪处理,提取有用信号。采用蝶形图进行缺陷的定性识别与报警,消除传感器移动的速度效应,并给出裂纹长度和深度的定量结果。融合传感器、信号检测、计算机采集和信号处理技术,研制并实现一套完整的ACFM可视化检测系统硬件实验平台和软件分析平台,通过大量的实验对工件裂纹进行检测,并对测试数据进行了分析。更多还原

【Abstract】 The alternating current field measurement (ACFM) technique is a new kind of the electromagnetic non-destructive testing (NDT) technique. This method can size the lengh and depth of crack on structure surface, which has no effect with lift-off, property of metal material and boundary effect. Based on the relevant research contents of the project of ACFM defect detection intelligent visualization system development and industrial applications which is sponsored by Science and Technology Development Plan of Shandong Province, this paper conducts the systematic research to the ACFM detection signal’s processing method and the application. The mathemactical model of alternating current field measurement is disscussed. Using the finite element numerical simulation method and the method of far-field element adopted to dispose a three-dimensionna unbounded field problem, rectangle and u-shaped incentive detector model and finite element model of ACFM is built up. Analysis of the distribution of perturbed magnetic is studied.The experiments verify the correctness of the simulation results,these can be used as the theoretic base to achieve quantitative measurement of surface cracks.The detecting coil size is designed to meet the "point" of the magnetic measurement,.Series probe is developed based on the rectangular, U-type magnetic core and a single, serialized array detecting coil.Based on the probe mentioned above,a kind of signal source and practicing circuit are designed.The testing system software based on virtual instrument is developed with application of object-oriented programming idea. Using digital filtering, wavelet analysis and other modern signal processing technology, combined with Labview and Matlab programming mixed method, to detect the weak signal de-noising processing and extract useful signal.Butterfly diagram used for qualitative to identify defects and to alarm,eliminating the effect of the speed of mobile sensors.Form the view of the quantitative point to give the length and depth of cracks.A testing system of the hardware experiment platform and the software analysis platform is built up,combined with the theory ,model and working Principle of alternating magnetic field technology.and based on sensors, signal detection,computer and signal processing. The workpiece crack is detected through many experiments carried out on and the test data are analyzed.更多还原