【作者】 胡祥超；

【导师】 罗飞路；

【作者基本信息】 国防科学技术大学 ， 仪器科学与技术， 2012， 博士

【摘要】 无损检测技术一个最重要的发展方向就是多种无损检测手段的集成及综合应用。本文从涡流检测以及电磁感应原理出发研究集成涡流无损检测技术，将传统单频涡流、交变磁场测量、脉冲涡流以及多频涡流无损检测技术结合起来，扬长避短，优势互补，不仅具有单一涡流检测方法的检测能力，而且通过统一的数据接口、一体化的软硬件系统平台，使得多种涡流检测方法实现资源共享和检测信息融合，降低对操作人员经验的依赖性，极大的提高缺陷检测的可靠性和检测效率。本文针对航空集成化、小型化、原位化、快速化的检测需求，对集成涡流无损检测系统设计以及关键技术，包含系统通用模型分析，检测系统结构分析及优化，系统架构分析与设计、检测方法及原理集成以及传感器优化设计、研制应用等方面开展了细致的研究工作。本文（课题）核心研究内容与主要创新点包括：讨论并分析了涡流检测技术的物理及理论基础，对涡流检测问题的通用物理模型和计算方法进行了探讨，对涡流传感器线圈的感生涡流分布及阻抗和磁场分布特性进行了深入的研究和讨论；通过分析各种涡流无损检测系统特性，以数字化、集成化、模块化为目标，对传统各种涡流无损检测系统进行了优化设计。以麦克斯韦方程为基础，用电磁位函数数学表征单频激励条件下的时谐电磁场问题。以轴对称简化模型描述传统的典型线圈型涡流传感器，进而在轴坐标下分析涡流效应对传感器阻抗以及磁场分布的影响。文中对几种常见涡流检测技术的系统特点进行了分析和讨论，通过优化设计部分系统组件，提取不同检测系统的共性，优化独立系统架构从而抑制系统差异，为集成无损涡流检测系统的深入研究工作奠定物理平台基础。对涡流检测原理和不同的涡流检测系统特点进行了深入的探讨和分析，提出了一种全新的涡流检测系统原理层通用模型和功能层通用模型；以该模型为指导，提出了一种涡流无损检测系统的“双总线分层系统架构体系”；以“双总线分层系统架构体系”为基础，以集成化、模块化、可复用为指导思想和设计思路，深入研究并设计了集成涡流检测信号发生器和集成涡流检测信号调理系统。不同的涡流检测技术在检测原理上具有一定的差别，对应的激励信号类型、信号处理方式等方面均有差异，通过分析涡流检测技术的基本检测原理，提取不同涡流检测系统的共性，采用模块化、集成化、可复用的设计思路和技术路线，提出了涡流检测系统的原理层通用模型；通过分析不同的涡流检测系统的功能模块构成，求同存异，并按细化功能形成模块，提出了功能层通用模型。以这两个模型为指导，提出了一种以顶层全局总线和底层局部总线相结合的双总线分层系统构架体系，其中顶层对应原理层通用模型，底层对应功能层通用模型。基于两个模型和双总线分层系统架构体系，深入研究并设计了集成涡流无损检测信号发生器和集成涡流无损检测信号调理两个子系统，为集成涡流无损检测系统的研究和设计奠定了工程专业基础。借鉴虚拟仪器“以软代硬”的设计思想，以集成化、模块化、可重构为系统设计目标，以工业计算机为基础平台，以“双总线分层系统架构体系”为指导，设计并实现了集成涡流无损检测系统。系统不仅能够实现ACFM、常规单频涡流检测、多频检测和脉冲涡流检测功能，而且通过统一的数据接口和系统平台实现资源共享和信息融合，是真正意义上的集成涡流无损检测系统。依据前面提到的系统模型和双总线分层架构设计思想，借鉴虚拟仪器“以软代硬”、“软件即仪器”的设计思想，综合考虑项目研究的实际，建立了基于工控计算机的系统平台。其中，顶层全局总线采用PCI总线，底层局部总线采用IIC总线。详细介绍了集成涡流检测系统的硬件平台、软件系统以及传感器等设计等。将D-S证据理论引入对不同的涡流检测手段的集成检测结果中来，对检测结果进行了数据融合，以置信概率为特征量来表征缺陷识别，提高了缺陷检测的准确性和检测概率。针对航空装备无损检测实际需求，通过相关实验验证了系统的检测性能。针对航空无损检测的实际需求，提出了一种全新的涡流无损检测方法—脉冲交变磁场测量技术（PACFM），该检测方法集成了脉冲涡流检测和ACFM交变磁场测量两种检测方法，通过优化传感器结构、信号处理方法、信号源激励模式等方面融合了PECT和ACFM技术的优势、抑制或消除了单一检测方法的缺点。通过比较分析实验研究，PACFM技术不尽具有良好的深层缺陷检测能力而且具备优异的缺陷定量能力。ACFM技术以场量测量为基础，具有能够定量评估缺陷尺寸、无需同被测物体接触、对提离效应不敏感等优点，但是一般只适用于被测物体表面缺陷的检测，对深埋隐藏缺陷的检测能力较差。脉冲涡流无损检测由于脉冲信号中含有丰富的频谱谐波分量，能够对不同深度的缺陷产生作用，在多层结构深层缺陷检测方面效果较好。然而，由于采用瞬态响应信号时域特征量进行分析，容易受到外界噪声干扰且提离效应影响明显，进而极大降低缺陷检出概率。针对这种实际情况，提出了一种脉冲交变磁场测量技术，该技术集成融合了两种检测技术各自的优势，降低或减少了各自的劣势，采用脉冲周期信号激励矩形传感器线圈，提取瞬态脉冲响应信号的特征量描述三维磁场场量值，采用场量测量和瞬态信号分析相结合的方法实现缺陷识别与定量评估。与传统ACFM技术相比，PACFM不仅具有等同的表面缺陷检测能力，而且具有优异的深层缺陷识别与定量评估能力。对脉冲交变磁场测量技术在深层缺陷的定量评估和定性分析方面进行深入的研究，引入并定义了“立体蝶形图”、“DPV-峰值偏差”以及“标准偏差比率”三个特征量，应用于缺陷的定性检测、定量评估以及缺陷分类中，基于脉冲涡流谱分析的研究方法，对双层复合结构中的缺陷进行了分类研究，提出了基于差分谱分析的三维缺陷检测信息FFT谱分析方法，能够实现良好的针对双层复合结构缺陷分类效果。在讨论了ACFM检测技术中采用的二维蝶形图判断模型的基础上，结合PACFM技术特点，提出了“立体蝶型图”的三维判断模型，该模型增加了一维信息量，不尽能有效提高缺陷检测的精度和准确性，亦能提高对包含传感器提离效应在内的干扰抑制；以“DPV-峰值偏差”为特征量，重点研究PACFM技术的缺陷扫描过程以及缺陷的定量评估；基于脉冲涡流谱分析的研究方法，对双层复合结构中的缺陷进行了分类研究，研究结果表明基于三维缺陷检测信息FFT谱分析方法能够取得有效的缺陷分类效果。本文的研究成果已通过专家鉴定，系统样机也已投入我军某新型战机的日常维护和定期检测中，真正满足了装备无损检测对集成化、小型化、快速化以及原位化的检测需求，受到应用单位的一致好评，有效地减少了维护人员的工作量，降低了对操作人员经验的依赖，并极大缩短了现场检修时间，提高了检测效率。更多还原

【Abstract】 Integrated eddy current non-destructive testing (IECNDT) including allthe advantages of different NDT techniques has been going to be theinevitable trend of eddy current non-destructive techniques in future.Integrated eddy current non-destructive testing technique has not only thecapability of single eddy current testing technique, but also higheraccuracy through the unifying data interface and data fusion. Accordingto the inspecting practical needs of miniaturization, in-situ and fastoperation, some in-depth studys on several crucial issues of IECNDT systemhad been made, for instance, system model analysis, eddy current testingsystem optimization and several other key aspects. The main researchcontents and innovations are as follows.Based on analysis of the physical and theoretical basis of the ECT,the common physical models and calculation methods of ECT are discussed.The impedance characteristic of the sensor and induced eddy currentdistribution researched. Some optimizations for ECT system are carried outincluding digital controlled bridge and the pulsed signal generator. Basedon Maxwell law, the electromagnetic potential function is used to expressthe time harmonic electromagnetic problem excited by sine signal and thetraditional coil sensor is expressed by a simplified axisymmetric model.The impendance and magnetic field distribution affected by eddy currenteffect are analyzed. In the paper, optimizations for ECT system are carriedout including a digital controlled bridge and the pulsed signal generator,which are based on the analysis of ECT system structures. All the researchwould support the work of integrated eddy current testing technique.A novel common principle-layer model and a common function-layer modelare proposed. Based on the models, a deep study on dual-bus and dividedlayer system architecture was carried out. A novel integrated eddy currentsignal generator signal generator and conditioner. There are differencesbetween different ECT techniques. Through analyzing principle of ECT, basedon the design thinking of integration, fast inspection and replaceconfiguration, a novel common principle-layered model is proposed. Throughanalyzing function of ECT system, a novel common functional layered model is brought forward. And then, dual-bus and divided-layered systemarchitecture studied. A design of integration eddy current signal generatorand conditioner is made based on the models, which support the work ofintegrated eddy current testing technique.IECNDT systems based on the thought of fast operation, modulation aredesigned and implemented. It is a hotspot to employ multiplenon-destructive testing methods for enhancing the probability of detection;meanwhile, there are increasing requirements of rapidity, intelligence andintegration in in-situ aviation NDT. A novel integrated ECNDT system wasdeveloped based on the universal model of eddy current testing system inprinciple and function. The system has modularized and reconfigurablesystem architectures and employs dual-bus structure: PCI and IIC. Itcontains not only functions of PECT, general ECT, MFECT, ACFM and AECT,but also integration of multiple ECNDT methods, like PACFM (PEC and ACFM).The system of integrated eddy current nondestructive testing has beensuccessfully used in some aviation filed, which has obtained a goodevaluation.Traditional alternating current field measurement (ACFM) technique hasadvantages of quantitative defect detection and non-contact feature, butpoor detective performances on deep-layer defects. Pulsed eddy currenttesting (PECT) has a better detectability in deep-layer defect, but poorerquantitative performances than ACFM, and moreover, it is easily interferedby lift-off due to ultilising transient signal analysis method so asdifficult to be applied practically. A method of alternating current filedmeasurement with pulsed signal excitation was proposed, which implementsdefect detection and quantitative evaluation by means of transient signalanalysis combined with3D magnetic field measurement based on pulsedresponse signal. Some features which can reflect the magnetic fieldtendency were extracted. Through the study we found that Pulsed AC fieldmeasurement has not only an equivalent detective performance on surfacedefects, but also an excellent performance on defect identification andevaluation of deep-layer defect.A deep study of defect detection for deep-layered structure is madeusing proposed PACFM. Some novel characteristic variables, for example, DPV, are proposed. Quantitative evaluation for deep-layercorrosion in aircraft multi-layer structure is extremely important forhealthy monitoring and lifetime prediction of aircraft. A novel AC fieldmeasurement method with pulsed excitation was proposed, which implementsdeep-layer corrosion detection and quantitative evaluation based on pulsedresponse signal using magnetic field measurement method. The feature whichcan reflect the magnetic field perturbation caused by corrosion wasextracted and the research on quantitative length evaluation for deep-layercorrosion on the basis of response signal fromBz probe was made. Moreoverthe experiments for studying the influences of different depth and widthof corrosions on the quantitative length evaluation were carried out.The results of this paper have been identified by experts. The systemprototype has been put into the day-to-day maintenance and periodic testingof a new type of aeroplane in our army, which turely meet the needs of thenon-destructive testing equipment integration, miniaturization, fast andin-situ detection and got the praise from application units. It haseffectively reduced the workload of the maintenance staff and dependenceon operator experience, moreover has greatly shorten the time on-sitemaintenance, improve the detection efficiency.更多还原