直流超导量子干涉器的无损检测研究

利用高温直流超导量子干涉器（DC SQUID）建立一套无损检测装置，对无磁不锈钢材料受到外力冲击后产生的剩余磁场进行了探测，利用电磁激励的方法，对有内部缺陷的铝板进行了试验研究，并对激励频率的选择进行了初步的讨论。     

直流超导量子干涉器无损检测的原理与应用

直流超导量子干涉器在弱磁测量领域有着广泛的应用，其中无损检测是它的重要应用之一，相对传统的电磁检测，该检测方法具有高灵敏度、高带宽和高空间分辨率的特点。介绍了该方法的检测原理和应用。     

超导量子干涉器弱磁检测钛合金中硬质合金夹杂结果的可视化

介绍了利用射频超导量子干涉器弱磁检测装置对钛合金中硬质合金夹杂检测结果的可视化，在线扫描的基础上，运用面扫描对试样进行检测，采用波形叠加显示，伪彩色三维投影图、三维强度图等方法对检测结果进行可视化显示。     

无损检测交变磁场测量法

准确测定缺陷的尺寸,对带缺陷结构的寿命评估具有十分重要的意义。交流磁场测量法是近年来兴起的一种评价表面缺陷的无损检测方法,它通过测量工件表面感应磁场的变化来进行材料中缺陷的定性定量,具有非接触的优点,广泛应用于结构的在役检测。     

多通道超导量子干涉仪的自动控制系统

为了方便射频超导量子干涉仪(rfSQUID)的广泛运用,研制了多通道射频超导量子干涉仪自动控制系统,系统可完成对多路超导量子干涉仪工作点自动调整和存储,实现了对多通道rfSQUID有效信号的处理和输出。并对系统工作的原理、硬件电路和相关的软件设计作简要介绍。     

超声无损检测的应用研究与进展

对当前国内外超声无损检测技术的应用与研究进行了总结,展望了今后的发展趋势与前景。     

光折变全息干涉计量术及其应用

光折变晶体是一种新型的记录材料,应用光折变效应,不需显影、定影等复杂处理,可实现实时观测,探索了光折变实时全息干涉法在光学检测中的应用,提出了实时监测火焰温度场的新技术,阐述了有关的原理,从理论上推导了有关的实验参数和实验条件,介绍了实验的过程,分析了最后得出的结果。     

On the application of magneto-optic films in NDE

Some applications of magneto-optic (MO) films in the field of nondestructive evaluation (NDE) are presented. The method for imaging and measuring of magnetic fields on micrometer scale is based on the analysis of changes of the magnetic domain structure caused by the detected field. A process of MO film evaluation and calibration is described. The existence of the leakage field around a fatigue crack in nonmagnetic austenitic material is detected by a highly sensitive MO film. An experimentally determined distribution of the excitation field of an eddy current probe is compared with results obtained by the finite element method (FEM) numerical procedure.     

Stray flux effects on the magnetic hysteresis parameters in NDE of low carbon steel

The magnetic minor hysteresis loops and parameters of low carbon steel plate samples annealed at different temperatures have been measured and compared with the results of ring samples. The influences of stray flux in the fringe areas of the plate on the magnetic properties were discussed with the help of a finite element approach. It is found that the coercivity H_C and the hysteresis loss W_H of all of the plate samples sharply deviate from the values of the corresponding ring samples with the same applied field amplitude H_a larger than 3000 A/m. It is proposed that the fringe areas of the plate sample are magnetized by the stray flux to an irreversible state at large Ha, and the remanent fields act against the applied field in the inverse direction, resulting in the extreme increase of H_C and W_H. Although these parameters measured at high-applied field can reflect the microstructure changes, low field results are preferable for the practical use.     

Experiment and simulation study of 3D magnetic field sensing for magnetic flux leakage defect characterisation

Magnetic flux leakage (MFL) testing is widely used to detect and characterise defects in pipelines, rail tracks and other structures. The measurement of the two field components perpendicular to the test surface and parallel to the applied field in MFL systems is well established. However, it is rarely effective when the shapes of the specimens and defects with respect to the applied field are arbitrary. In order to overcome the pitfalls of traditional MFL measurement, measurement of the three-dimensional (3D) magnetic field is proposed. The study is undertaken using extensive finite element analysis (FEA) focussing on the 3D distribution of magnetic fields for defect characterisation and employing a high sensitivity 3-axis magnetic field sensor in experimental study. Several MFL tests were undertaken on steel samples, including a section of rail track. The experimental and FEA test results show that data from not only the x- and z-axes but also y-axis can give comprehensive positional information about defects in terms of shape and orientation, being especially advantageous where the defect is aligned close to parallel to the applied field. The work concludes that 3D magnetic field sensing could be used to improve the defect characterisation capabilities of existing MFL systems, especially where defects have irregular geometries.     

Mechanical damage detection using magnetic flux leakage tools: modeling the effect of dent geometry and stresses

We have used three-dimensional (3D) magnetic finite element analysis (FEA) to simulate the MFL signal from a circular dent geometry with associated residual stresses. Strain distribution information around the dent was obtained from an earlier work using finite element structural modeling. In the magnetic FEA dent model, the localized residual stresses were simulated by assigning appropriate values of magnetic anisotropy to the relevant magnetic regions. The simulated flux leakage patterns were found to be in good agreement with the experimentally observed MFL patterns associated with dent shape as well as with the stress effects from the dent.     

探地雷达技术的回顾与展望

百余年来，探地雷达在技术上逐步成熟，在地下探测领域发挥着越来越重要的作用。主要介绍国外在探地雷达的设备研制、数据处理和具体应用等方面的发展历程及研究动向，也简要介绍了探地雷达在我国的发展情况。     

Magnetic NDT Technology for characterization of decarburizing depth

From practical point of view, determining the decarburizing depth is important in quality control of steel parts as it has undesirable effects on the mechanical properties such as hardness, wear and fatigue resistance. Traditional destructive methods of determining the depth of decarburized layer include metallographic and hardness test which are time-consuming and costly. Since response to eddy current is sensitive to chemical composition as well as microstructure of the material under consideration, the non-destructive method can be used in determining the depth of the decarburized layer in steel parts. It is mainly due to the difference in the microstructures, and as a result, in the magnetic properties of the decarburized layer with other parts of the specimen. In the present study at the first step, the magnetic properties of decarburized carbon steel bars (0.45 wt.% C) were evaluated using an electromagnetic sensor and correlated with the microstructure changes from surface to the core of the sample. At the second step the steel bars were held in 900 °C for different period of times and the depth of decarburizing layers were measured using hardness testing. Finally, the non-destructive eddy current technique was used and the response of test samples to the induction current including primary and secondary voltages, normalized impedance, phase angle and harmonic analysis parameters were investigated. Results show an acceptable accuracy in comparison to the destructive method.     

磁测应力技术的现状及发展

磁测应力是近几年发展起来的最新无损检测技术，分为金属磁记忆检测技术和基于逆磁致伸缩效应的磁各向异性检测技术。该技术适用于铁磁性金属构件失效的早期诊断，特别是在铁磁构件的疲劳强度和寿命评估研究中更具广阔的发展空间。介绍了磁测应力技术的基本概念、特点及国内外的研究现状，分析了目前存在的问题及其发展趋势。