共查询到20条相似文献,搜索用时 140 毫秒
1.
裂纹缺陷的定量评估是无损检测的一项重要研究内容,本文采用交变磁场测量技术对平板裂纹缺陷进行了检测.在分析交变磁场测量技术原理的基础上,首先在大型电磁仿真软件AN SY S中建立了交变磁场测量模型,包括三组不同参数的裂纹缺陷和检测线圈相互垂直的两种传感器模型,然后用这两种传感器分别对不同缺陷进行了检测,研究了裂纹长度、深度和宽度变化对水平方向和垂直方向检测电压的影响规律,提取出了对长度和深度进行定量的特征量.最后,采用实验的方法对仿真结果进行了验证,实验结果的规律与仿真结论相一致,证明了仿真结果的正确性.从而为裂纹缺陷在实际中的检测和定量提供了借鉴. 相似文献
2.
3.
脉冲涡流技术是一种可以对飞机多层结构中缺陷实施有效检测的方法。交变磁场测量技术是一种精确测量表面裂纹的非接触式无损检测方法。提出了脉冲涡流磁场测量(PECFM)技术,并对其进行了理论分析。在设计了相应传感器的基础上,对多层铝板结构中的缺陷进行了检测实验,实验结果与理论分析相一致。实验证明PECFM技术可以有效地实现多层结构中缺陷的识别与定量检测。可以预见,PECFM技术将会在无损检测领域中发挥很大的作用。 相似文献
4.
5.
黄延 《理化检验(物理分册)》2013,(4):251-254
某地铁列车车钩钩头法兰部位在磁粉探伤过程中发现磁粉聚集现象,通过对磁粉聚集区域切片进行剖面宏观分析、硬度测试、化学成分分析、金相检验、扫描电镜分析以及能谱分析,对磁粉聚集原因进行了分析。结果表明:钧头法兰磁粉聚集区域存在焊接特征,且焊缝中存在气孔、夹渣等焊接缺陷,靠近焊接熔合线的热影响区存在疏松铸造缺陷;在磁粉探伤时,这些缺陷位置会形成漏磁场,使磁粉在漏磁场处聚集,从而形成磁粉聚集。 相似文献
6.
7.
8.
9.
10.
11.
12.
为解决火炮零部件上裂纹等缺陷的检测问题,依据漏磁检测原理及缺陷漏磁场偶极子模型,设计了火炮零部件漏磁检测装置并进行了工程化实现.考虑到火炮零部件结构多样性,采用霍尔器件和磁阻传感器设计了多种结构的检测装置;针对漏磁信号中存在干扰信号和系统噪声的问题,采用自适应滤波和MORET-P小波变换技术,进行了信号的预处理.应用结果表明:该装置原理可行,多种结构的检测装置满足了不同火炮零部件的检测需要,自适应滤波和MORET-P小波变换技术较好地剔除了干扰信号和系统噪声,有效提取出缺陷信号. 相似文献
13.
为了克服大行程麦克斯韦磁阻驱动器在大气隙下漏磁大幅增加、气隙区磁场分布不均匀且非线性强烈等现象导致的磁场和推力解析模型精度较低等问题,利用考虑综合高斯函数的加权漏磁系数的磁路建模方法,改进了磁阻驱动器的三维漏磁分布计算方式,并得到了可准确描述其推力与输入电流函数关系的解析模型,从而为该类驱动器的设计及控制提供重要依据。首先,建立了大行程麦克斯韦磁阻驱动器考虑漏磁前后的工作磁路,分析了永磁偏置磁路的作用及使用永磁偏置结构后仍具有非线性的原因,并利用安培环路定律和磁路的欧姆定律以及磁场的可叠加性,建立了该磁阻驱动器的推力解析模型。然后,为了优化解析模型,提出了基于高斯曲线的加权漏磁系数计算方法,同时利用有限元仿真软件对大行程麦克斯韦磁阻驱动器的三维磁场分布及漏磁系数进行了分析计算,得到了考虑加权漏磁系数的推力解析模型。最后,搭建了大行程麦克斯韦磁阻驱动器推力测试系统,并通过对比优化前后解析模型计算推力与仿真推力和实测推力,验证了解析模型的准确性。结果表明,优化后解析模型的均方根误差仅为优化前的11.1%,其精度得到有效提升;同时,优化后解析模型计算推力与实测推力之间的均方根误差小于0.6 N,精度较高。研究结果对高端微纳制造装备与测量仪器中新型超精密驱动部件的设计有一定意义和参考价值。 相似文献
14.
Keiji Tsukada Kousuke Miyake Daichi Harada Kenji Sakai Toshihiko Kiwa 《Journal of Nondestructive Evaluation》2013,32(3):286-293
Resistance spot welding technologies are widely used in industry. A highly reliable monitoring method is needed to effectively weld and create a robust structure. We developed a combined technique using magnetic flux penetration and an eddy current test (ECT). The magnetic measuring system consists of a pair of magnetic probes having an induction coil and detection coil, a lock-in amplifier, a current source, and a personal computer. The magnetic flux penetration through both surfaces at the weld was measured at low frequency. The ECT was performed at each surface with multiple frequencies. The magnetic flux penetration method showed good correlation with the destructive shear test because of the change in permeability due to the formation of the nugget. The ECT method reflected the depth profile of the nugget and was effective for determining a defective product. 相似文献
15.
16.
利用计算机及数模、模数转换技术,在原有的永磁材料自动控制测量系统基础上,将磁通、磁场两个物理量溯源到电压V、时间t、长度m三个基本物理量,实现测量系统高精度的自我校准。 相似文献
17.
T. Brys S. Czekaj M. Daum P. Fierlinger D. George R. Henneck Z. Hochman M. Kasprzak K. Kohlik K. Kirch M. Kuzniak G. Kuehne A. Pichlmaier A. Siodmok A. Szelc L. Tanner 《Journal of research of the National Institute of Standards and Technology》2005,110(3):173-178
For highly sensitive magnetic measurements, e.g., a measurement of the neutron electric dipole moment (EDM), the magnetic field has to be stable in time on a level below picoTesla. One of several measures we employ to achieve this uses an external field coil system which can stabilize the ambient external field at a predefined value. Here we report on the construction and characterization of such a system in the magnetic test facility at PSI. The system actively stabilizes the field along the axis of the EDM experiment by means of four coils in a Helmholtz-like configuration. Additional coils serve to compensate for transverse ambient field components. Because of the long integration times in the EDM experiment (about 100 s or more) only slow disturbances have to be corrected for. The performance of the system has been measured using static and moving magnetic sources and suppression factors in excess of 200 have been observed. 相似文献
18.
19.
The development of a laboratory-based tailor-welded blank (TWB) inspection system using the principles of magnetic flux leakage (MFL) is presented. The effects of variations in inspection system operating parameters are quantified to allow for optimized system performance. The parameters examined include the applied magnetic field strength, inspection scanning velocity, spatial resolution of acquired signals, specimen end effects, and pole piece liftoff. The results indicate that this inspection method is relatively insensitive to operating parameters and is therefore robust. 相似文献
20.
W. Sharatchandra Singh S. V. Sagar Kumar B. Purnachandra Rao P. Ravindar 《Research in Nondestructive Evaluation》2013,24(5):253-268
ABSTRACTFor enhanced detection of flaws in engineering components using magnetic flux leakage (MFL) technique, measurement of the leakage magnetic field components along the three perpendicular directions is beneficial. This article presents the three dimensional-magnetic flux leakage (3D-MFL) modeling and experimental studies carried out on carbon steel plates. Magnetic dipole model has been used for the prediction of MFL signals and images. Sensitivity of the MFL signals peak amplitudes of tangential (HX), circumferential (HY), and normal (HZ) components with respect to flaw length, width, depth and lift-off have been studied. A 3D-GMR sensor has been used for simultaneous measurement of all the three components of leakage magnetic fields from surface flaws in 12 mm thick carbon steel plates. The experimental MFL images have been compared with the model predicted MFL images. The sensor has shown the capability to detect and image 0.9 mm deep surface flaws with a signal to noise ratio of 8 dB. Principal component analysis (PCA)-based image fusion has been performed for fusion of the 3D-MFL images to obtain a geometrical profile of the flaws. Study reveals that 3D-GMR enhances the capability for detection of flaws having irregular geometries. 相似文献