声学综合无损检测技术

论述了检测复合材料和胶接结构不连续（缺陷）的新型多模综合无损检测技术。该技术以声与超声检测技术为基础,包含五种不同检测模式,用以检测复合材料与胶接结构的失粘、脱粘、分层、疏松、夹芯压皱及其他缺陷。它适用于复合材料与构件的制造、维修和使用现场。它的适用对象范围广泛,几乎覆盖了现有常用的复合材料和胶接结构。它的检测可靠性高,重复精度好。文章还讨论了组成多膜声学综合胶接检测仪的五种不同检测模式的原理,并从我们和国内外同行的大量实践经验出发,说明了综合无损检测技术的巨大发展前景。     

Non-destructive Imaging of Standard Cracks of Railway by Photoacoustic Piezoelectric Technology

The photoacoustic piezoelectric (PAPE) technique is an effective non-destructive testing technique for detecting defects in materials. In this paper, Chinese national standard railway cracks have been detected by thermal wave imaging based on the PAPE technique. First, the theory of the PAPE technique has been introduced and the corresponding imaging principle has been analyzed. Second, the corresponding experimental system has been setup, and the imaging tests have been carried out. Third, two kinds of standard cracks have been examined by the imaging system. The results show that thermal wave imaging based on the PAPE technique can effectively image and identify the cracks at different depths, which lays a foundation for practical application to the detection of rail cracks.     

在役绝缘子失效特征与无损检测

在电网各个环境中运行的不同种类绝缘子，长期服役后都会不同程度地产生失效，导致故障事故的发生，对电网可靠性带来了极大地潜在威胁，研究绝缘子的失效特征对于指导绝缘子安全检测具有十分重要的意义。本文基于在役绝缘子种类繁多和结构复杂的特点，分析绝缘子失效特征和损伤部位，提出了利用无损检测技术检测绝缘子损伤缺陷的方法。     

Integrated Piezoelectric Ultrasonic Receivers for Laser Ultrasound in Non-destructive Testing of Metals

Thick (>50 μm) piezoelectric films have been deposited directly on top of steel and aluminum substrates as integrated ultrasonic transducer (IUT) receivers to detect laser generated ultrasound. The film fabrication is based on a sol-gel spray technique. In this study IUTs intrinsically acting as bulk longitudinal wave receivers use various mode conversion approaches and serve as longitudinal, shear, symmetric, anti-symmetric and shear horizontal plate wave receivers. Different laser generation conditions such as point and line sources of different sizes are also applied to investigate the capabilities of IUT receivers. Ultrasonic measurements on metal substrates with planar and curved surfaces at temperature up to 400°C using laser generated and IUT ultrasound receiver are demonstrated.     

陶瓷基复合材料无损检测研究进展

陶瓷基复合材料的各向异性和不均匀特性,以及在航空航天领域应用的紧迫性,使得采用无损检测(NDT)方法对其进行质量控制及保证是个非常重要而艰巨的任务.综述了陶瓷基复合材料无损检测的发展现状,阐释了超声波、红外热成像和工业CT技术的检测原理及其在陶瓷基复合材料无损检测的应用进展.     

压力容器无损检测技术的探讨

介绍了无损检测的几种方法,并进一步说明了这几种检测方法的使用范围及优缺点,着重分析了射线检测法与超声波检测法之间的关系及这两种方法使用时应注意的事项.     

Portable Automated Radio-Frequency Scanner for Non-destructive Testing of Carbon-Fibre-Reinforced Polymer Composites

A portable automated scanner for non-destructive testing of carbon-fibre-reinforced polymer (CFRP) composites has been developed. Measurement head has been equipped with an array of newly developed radio-frequency (RF) inductive sensors mounted on a flexible arm, which allows the measurement of curved CFRP samples. The scanner is also equipped with vacuum sucks providing mechanical stability. RF sensors operate in a frequency range spanning from 10 up to 300 MHz, where the largest sensitivity to defects buried below the front CFRP surface is expected. Unlike to ultrasonic testing, which will be used for reference, the proposed technique does not require additional couplants. Moreover, negligible cost and high repeatability of inductive sensors allows developing large scanning arrays, thus, substantially speeding up the measurements of large surfaces. The objective will be to present the results of an extensive measurement campaign undertaken for both planar and curved large CFRP samples, pointing out major achievements and potential challenges that still have to be addressed.     

电化学沉积法修复混凝土裂缝的研究进展

从电沉积法修复混凝土裂缝的机理、电沉积溶液的选择、电沉积效果的表征及其影响因素、电沉积方法修复后混凝土性能的改善4个方面论述了电化学沉积法修复混凝土裂缝的研究进展.探讨了对电沉积法修复混凝土裂缝的机理,分析了电沉积溶液的选择要求,对比了不同学者关于电沉积效果的表征方法及其影响因素,并归纳了电沉积方法修复后混凝土性能的改善,最后提出电沉积方法对混凝土裂缝的修复机制、愈合效果评价、电沉积层与钢筋混凝土结构基体材料界面结合机制等方面还有待进一步的研究.     

Rectification of Oblique Cracks in Fracture Toughness Testing

A technique for rectification of oblique crack fronts is described. It involves out-of-plane bending fatigue loading of the specimens. The method can be valuable in cases when residual stresses or other causes precludes a straight crack front being produced by standard fatigue loading in the process of preparing specimens for fracture toughness testing. This revised version was published online in July 2006 with corrections to the Cover Date.     

振动法在纤维增强材料结构探伤中的应用

本文通过建立纤维增强材料的有限元模型及模态测试,以模态比例因子为目标参数,修正有限元模型.采用模态力留数的方法,实现对纤维增强结构的无损探伤.为验证方法的有效性,采用人为添加附加质量的方法,测试附加质量前后的模态振型,通过模态力留数,显示故障点位置及实验数据,能准确识别出添加质量点的位置.     

弹丸结构缺陷电磁超声无损检测技术综述?

介绍了弹丸结构缺陷的主要形式与危害,分析了针对弹丸结构缺陷进行电磁超声无损检测的目的意义,阐述了电磁超声无损检测技术应用于批量生产的弹药装备结构缺陷的快速自动化检测的优势,列举了国内外针对弹丸结构缺陷进行超声无损检测的工程应用实践。最后,针对我国结合电磁超声无损检测技术开展弹药生产质量监督给出了几点建议。     

Sparse Representations to Replace TOFD Images in Non-destructive Testing of Materials

This paper describes a proposed method for the selection of relevant samples of ultrasonic signals during automatic material inspection. Instead of the well-known time of flight diffraction (TOFD) images, data are stored as a sparse matrix in which the elements only indicate whether a defect has been detected. This technique avoids storage of useless signals received during probe displacement in cases of low and high signal-to-noise ratios that correspond to coarse-grained and fine-grained materials, respectively. The approach is based on comparing the positions of maximum amplitudes, which are randomly located when signals only consist of noise but are in the same signal range when a defect is detected. The matrix elements are then applied as inputs to a self organizing map by neural networks to produce a normalized sparse matrix as the output, with a constant number of elements. This approach will be beneficial to enable the use of selected data in intelligent systems requiring a fixed number of inputs to characterize defects.     

Novel Coupled Electric Field Method for Defect Characterization in Eddy Current Non-destructive Testing Systems

This article presents a defect modeling in eddy current non-destructive testing systems by using a new developed method called coupled electric field. It permits to improve qualitatively several models developed so far by many authors using coupled circuit methods that consider the defect only as loss of material. However, a defect can occur with a finite conductivity such as impurity, small burns and micro-solder. For this reason, this investigation consists of extending the coupled circuit method to the modeling of this kind of defects. The proposed approach consists of firstly considering the defect as an electric conductive volume and secondly changing the state variable presenting the electric current by the electric field one. This procedure permits expressing explicitly the impedance variation caused by the presence of an axi-symmetrical defect according to its characteristics. The comparison between the impedance variations calculated using finite elements method and the proposed one demonstrates a very good concordance. After this validation, the study covers also the influence of the defect shape and position on encircling probe impedance. This method is interesting since it permits a fully characterization of this kind of defects and facilitates the inversion process. Moreover, using a 3D finite element observation, this fast tool of simulation can be adapted for a fast phenomenological modeling of asymmetrical configurations.     

超声无损检测减压炉加热管内表面结焦层

基于超声波在多层介质中的传播规律,探讨超声波技术检测加热管内表面结焦层的可行性。研究结果表明:超声波技术无损评价炉管内壁结焦层厚度是可行的;超声回波信号的幅度、周期性以及波形的畸变程度可作为结焦层厚度变化的表征指标;无焦区,回波清晰,周期性较好,幅度较高;薄焦区,回波幅度减少,周期性较好,回波略有畸变;厚焦区,回波幅度明显降低,畸变严重。     

激光电视全息技术及其在无损检测中的应用

激光电视全息技术是一种测量物体表面微小变形的非接触式测量技术.与常规检测方法相比,它具有高精度、全场、实时测量等特点,有着重要的理论研究和实用价值,是当前无损检测领域研究热点之一.本文介绍了激光电视全息技术的基本原理和特点、国内外在无损检测领域的应用成果和最新研究进展,并探讨了未来的发展趋势.     

某型航空发动机篦齿盘裂纹的原位涡流检测

针对某型航空发动机篦齿盘上产生的裂纹缺陷,在不拆分发动机的前提下,提出采用涡流检测的方法对篦齿盘进行原位无损检测．设计完成了一套可用于篦齿盘裂纹原位检测的涡流无损检测系统．采用正交型锁相放大器对涡流检测信号进行处理,提高了信号检测精度同时达到了抑制干扰的作用．在标准检测试件和模拟试件上分别进行了试验,试验结果表明,该涡流检测系统可以实现航空发动机篦齿盘裂纹缺陷的原位检测,并且可以定性判断裂纹的深度．     

Non-destructive Testing of Paint Coatings on Steel Plates by Ultrasonic Reflectometry

An ultrasonic reflectometry method has been used successfully to detect elasticity changes following the curing of 100  \(\upmu \) m thick epoxy films (DGEBA-PAA) coated onto 1.5 mm thick steel plates. The method employs a goniometric apparatus to measure the reflection coefficient amplitude around 5 MHz followed by a standard FFT analysis of the reflected signal. A specific ultrasonic wave mode was identified which was dependent on, and correlated with, the presence of the coating layer. The goniometer angle associated with this mode was different from that associated with Lamb modes of the plate, enabling the new mode to be detected reliably. The sensitivity of the new mode to variations in the paint mass density, longitudinal and transverse velocities and thickness has been quantified numerically by using Brekhovskikh’s model with due account taken of the finite width of the ultrasonic fields of the transducers. The method was tested for the detection of the evolution of the coating elasticity during curing at 80  \(^{\circ }\) C for 400 h. Compensation was applied to correct for the effect of the natural swelling of the paint layer on the angular position of the tracked mode, and this was validated experimentally. The evolution of the angular position was found to offer a reliable means to detect elasticity changes during the cure of the coating. The mass density variation in the coating during cure only weakly affected the angular position. This method will provide a promising tool for the non destructive evaluation of paint coatings, particularly in service for the detection of ageing effects in the longer term.     

脉冲漏磁无损检测影响因素分析

脉冲漏磁无损检测系统可以用来检测带保温层管道的腐蚀缺陷,其主要参数的设计对提高系统的检测性能具有重要意义。分析了检测线圈尺寸、激励脉冲信号的频率、电压、占空比以及边缘效应等因素对检测结果的影响,给出了检测结果随这些因素的变化规律,为系统参数的优化设计提供了依据。