相位放大技术在远场涡流检测中的应用

远场涡流(RFEC)技术是一种能穿透金属管壁的低频涡流检测技术,该技术适合于金属管道,尤其是铁磁性管道的在役检测.但是,由于远场涡流检测时频率低且相位变化微弱,为了更好地通过远场信号分析判断被检样品的不同缺陷,仪器必须具备相位放大功能.简要介绍爱德森公司研究开发的涡流相位放大技术.     

Pulsed remote field technique used for nondestructive inspection of ferromagnetic tube

Remote field eddy current (RFEC) technique is an effective method for measurement of ferromagnetic tube. However, traditional RFEC is unable to differentiate the internal and external defect and the probe has a long length. Pulsed eddy current techniques excite the induction coil with a pulsed waveform and have the richness of frequency harmonics. The wideband excitation is thought to be a potential in providing more information about the flaw. In this paper, pulsed RFEC technique is used to inspect ferromagnetic tube. The finite element analysis and experiment method is used to give a thorough analysis of the influence effect with the variations of the system parameters. Results show that this technique effectively combines the advantages of RFEC and pulsed excitation, which not only acquires more inspection information, including measurements of inner diameter of tubes, internal and external defects, but also reduces the length of probe and power consumption. The agreement between simulation and experiment shows that the present method is correct.     

涡流Bobbin探头性能评价参数试验

为了评价和比较传热管涡流检查使用的Bobbin探头，通过对于影响检测结果的基本要素的分析，提出涡流Bobbin探头的性能评价参数。采用自制探头和进口探头进行了比较试验。通过对试验结果的分析，总结出涡流Bobbin探头的性能评价方法，并最终给出了对材料为08X18H10T不锈钢、尺寸为φ1Gmm×1．5mm的蒸汽发生器传热管涡流检查的Bobbin探头（西11．0mm）的验收指标，为此类探头的性能测试和比较提供了参考。     

大口径管道远场涡流缺陷检测仿真建模

利用有限元分析软件ANSYS对大口径油气管道的远场涡流检测进行了仿真研究。根据远场涡流的特点,采取局部法进行三维仿真,即先对无缺陷的二维轴对称远场涡流模型做仿真,得到缺陷外围区域的磁场分布,再以此为边界条件对缺陷区域做三维仿真。该方案显著降低了模型的规模,提高了远场涡流缺陷检测仿真的效率和准确性,使得对大口径油气管道的远场涡流仿真得以在PC机上完成。     

远场涡流技术检测带翼片管的研究

远场涡流检测对高导电管的管壁上的缺陷非常敏感，具有透壁性。探讨应用远场涡流技术检测带翼片(散热片或金属隔板组件)钢管的有关问题，分析了管外翼片对远场涡流的耦合特性和缺陷信号的影响，得出了翼片响应信号与缺陷信号的关系及缺陷信号的提取方法。     

Design of an eddy-current array probe for crack sizing in steam generator tubes

This paper describes an arrayed multi-coil probe, newly developed for the testing and crack sizing of steam generator tubes by eddy current testing (ECT). The testing speed, the high sensitivity to shallow cracks and the crack sizing are the present requirements in ECT. Because of the multi-coil arrangement, the arrayed probe has a high detection speed around the whole tube, without the need for rotation. It is realized from former studies that knowing the number of cracks, their directions, and their positions beforehand is of great help in crack sizing. Thus, not only the sensitivities but also the spatial resolutions are important. Numerical simulations are applied to help the design of the probe from the viewpoint of the crack sizing of steam generator tubes. Experiments show that the present probe provides both a high detectability and a remarkable capability of reconstructing the shallow cracks of a tube.     

加热器碳钢管内插式探头涡流探伤试验

用内插式探头磁化涡流和远场涡流检测技术对８个电厂４８台加热器碳钢管进行了检测,试验结果表明,磁化涡流对碳钢管道孔和内壁缺陷检测灵敏度较高,对外壁缺陷检测灵敏度较低,容易区分内外壁缺陷;远场涡流对碳钢管通孔检测灵敏度较低,地内外壁缺陷检测灵敏度较高,但难以区分内外壁缺陷。     

涡流检测超轻夹层栅格材料的有效性

研究了涡流检测技术对超轻多孔夹芯板无损检测的有效性。通过对波纹夹芯板和点阵桁架夹芯板的涡流检测进行建模和有限元数值模拟,研究了夹芯板焊部裂纹信号和焊部噪声信号的特征,考察了焊部形状尺寸变化对检测信号的影响,验证了利用多频信号演算方法(MFA)提取裂纹信号的可行性。计算结果表明,对于波纹夹芯板和点阵桁架夹芯板,表层和夹层焊接部位的噪声信号和裂纹信号具有明显不同的频率相位特征,裂纹信号对激励频率更敏感。焊部检测信号中的裂纹信息可利用多频信号演算方法进行分离,并可进一步对裂纹的存在和大小进行定性和定量分析。     

Eddy current flaw characterization in tubes by neural networks and finite element modeling

For quantitative flaw characterization in steam generator tubes, inversion of eddy current testing (ECT) signals in an automated fashion is strongly desired. In this paper, we report our effort to develop a systematic approach for flaw characterization in tubes by the novel combination of neural networks and finite element modeling.Specifically, the finite element model that can predict ECT signals from axisymmetric flaws in tubes was developed, and its accuracy was verified experimentally. Using this model, an abundant synthetic database with 400 ECT signals generated from 200 axisymmetric machined grooves in four types has been constructed with two test frequencies per flaw.For the automated inversion of ECT signals, a total of 22 features have been extracted from each flaw. Then, a set of 10 features has been selected for flaw classification, while the other set of 10 features for flaw sizing. For the determination of the flaw type and the flaw size parameters, we have proposed an intelligent flaw characterization system that adopts two different paradigms of neural networks: probabilistic neural networks for flaw classification and back propagation neural networks for flaw sizing.The performance of this system has been investigated using the synthetic ECT signals in the database. The excellent performance presented here, even though it has been obtained from synthetic flaws representing machined grooves in tubes, demonstrates the high potential of this system to serve as a robust tool for practical flaw characterization in tubes.     

涡流法无损检测铝合金管材可靠性的研究

总结了在生产现场的涡流检测过程中如何选择最佳探伤参数,解决管材本底噪声大的问题,提高铝合金薄壁管材涡流检测的准确性和可靠性。     

凝汽器传热管管板区涡流检测盲区试验

提出了凝汽器传热管管板区Bobbin技术检测的盲区问题,分析了盲区的成因,并设计模拟管板开展了试验研究。结果表明,管板结构信号对Bobbin探头检测能力影响较大,在距离TTS 8 mm范围内形成检测盲区;而且,越靠近胀管末端,其影响越大。最后,提出了用CXB技术解决Bobbin检测技术管板盲区问题的设想。     

螺栓裂纹的涡流自动探伤技术和系统

研制了全自动涡流螺栓检测系统。系统采用多个探头移动扫描，螺栓同时旋转，头部呈锥角的自比差分点探头及阻抗平面显示技术，实现对螺栓包括头杆结合部、光杆和螺杆处的纵横裂纹全方位检测。     

巨磁阻传感器在涡流检测中的应用

巨磁阻传感器是一种新型的磁性传感器,与传统的磁性传感器相比,有着灵敏度高、可靠性高和线性好等优点。介绍巨磁阻传感器的原理及其在涡流检测中的应用,实例表明采用巨磁阻传感器的涡流检测系统可以得到很好的检测结果。     

新型脉冲远场涡流传感器检测性能的仿真分析

远场涡流技术由于不受集肤效应的限制,其可实现原位检测的优点成为解决大厚度非磁性金属平板的有效途径。在前期研究工作基础上,介绍了新型非磁性平板构件脉冲远场涡流传感器的设计原理,并仿真分析了基于连通磁路传感器对不同走向缺陷及不同厚度平板的检测能力。结果表明:将脉冲远场涡流技术应用至非磁性金属平板检测时,检测信号所受扰动主要是缺陷对感应涡流的扰动,而非缺陷对磁场的扰动,这与其检测铁磁性材料存在根本的区别,同时,其可检测的板材厚度达到了25 mm,研究结果为脉冲远场涡流技术在航空领域的应用提供了有益的探索。     

CIVA仿真对核电站蒸汽发生器传热管涡流检验技术的应用评价

研究了CIVA仿真平台对核电站蒸汽发生器传热管涡流检验技术的应用评价。主要利用CIVA仿真平台，对蒸汽发生器传热管检验中所使用的标定管典型人工缺陷进行了涡流检测仿真，并对比了仿真模拟结果与实际检测结果，以验证该技术的可靠性与稳定性。     

Application of eddy currents induced by permanent magnets for pipeline inspection

This paper presents an alternative to the common concentric coil method to induce low-frequency eddy currents in ferromagnetic pipe and tubes. Pairs of permanent magnets rotating around the central axis of these cylinders in proximity of the surface can be used to induce high current densities in the material that is the object of the inspection. Anomalies and wall thickness variations are detected with an array of sensors that measure local changes in the magnetic field produced by the current flowing in the material. This electromagnetic technology is being developed for pipeline inspection platforms that either crawl slowly inside a pipe to maneuver past physical barriers or are pushed by flexible rods. These devices move down the pipeline independent of the product flow, and potentially stop for detailed defect assessment. Fundamental finite element modeling analysis and experimental investigations performed during this development have led to the derivation of a first-order analytical equation for designing rotating exciters and positioning sensors. The rotating permanent magnet system has the potential for broader application because the sensor configurations can be small in physical size, allowing them to pass obstructions that currently prevent inspection using available NDE implementations.     

电涡流检测系统的参数设置依据

建立了电涡流检测系统的涡流场亿真分析模型，分析了工作频率、测距、涡流的分布以及零件缺陷对系统中感应磁场的影响，并以此作为电涡流检测系统的参数设置依据。     

阵列探头在传热管管板区涡流检测中的应用

传统上采用Bobbin探头进行凝汽器传热管涡流检测时存在管板盲区问题。基于传热管管板区涡流检测需求,研究了CXB型阵列探头在此领域的应用。通过设计制作凝汽器模拟管板,开展了试验研究。试验发现,CXB探头能够有效解决涡流检测中Bobbin探头在传热管管板区存在的盲区问题。同时,试验解决了CXB探头对于缺陷的定量评定难题。最后给出了现场检测中的实际应用结果。     

列管式反应器的涡流检测

列管式反应器的泄漏将严重影响化工生产。采用双频涡流方法检测其列管及管板，介绍了检测传感器的设计和制作，分析和研究了缺陷和涡流信号响应特征之问的关系。对比分析了表面凹坑、夹渣及裂纹等缺陷的阻抗图特征。验证了根据阻抗图幅度和相位分析判定缺陷技术的优点。实践表明，涡流检测速度快、灵敏度高且测试结果准确。     

Fortschrittliche Korrosionsprüfung von Rohren aus ferromagnetischem Material mit dem Wirbelstrom-Fernfeldverfahren

Modern corrosion inspection for ferromagnetic tube material with remote field eddy current technique Heat exchangers are used in nearly all fields of energy supply, chemistry, petrochemistry and shipping. Unexpected failures of heat exchanger tubing cause inadmissible mixture or discharge of the enclosed media. The aim of modem corrosion inspection is therefore avoiding production disturbances by early detection Of damages. Currently used electromagnetic techniques for inspection of heat exchanger tubing of ferromagnetic materials are presented. The remote field eddy current technique shows advantages compared to the flux leakage technique and the magnetic biased eddy current technique.