一种基于磁真空泄漏原理的漏磁无损检测新方法

New MFL Nondestructive Testing Method Based on Magnetic Vacuum Leakage

在磁折射的进一步推导与分析基础上形成一套缺陷磁真空泄漏原理。提出一种基于磁真空泄漏原理的漏磁检测新方法:清除较强的背景磁场,让被检测导磁构件体内磁通在缺陷处无反向背景磁压最彻底地泄漏到所创造的磁真空区域,形成最大化漏磁场并被置于该区域的磁敏元件所感应。采用有限元仿真与试验对该原理及其方法进行可行性论证。阐述该原理与方法的特性所在。磁真空泄漏原理及其方法使得缺陷漏磁场在空间范围和强度上均有所增大,可提高磁敏元件的探测提离距离,从而可实现真正的远距离非接触式漏磁探伤。另外,可消除或减少传统磁空气泄漏漏磁检测方法中由强的背景磁场所引起且一直存在的缺陷信息失真、磁噪声以及某些磁敏元件如霍尔的饱和不工作现象。磁真空泄漏原理与方法的提出与分析在促进漏磁检测方法的进一步应用的同时,也进一步地丰富和完善漏磁检测理论体系。

On the basis of the further derivation and analysis of magnetic refraction,a new principle of magnetic flux leakage（MFL） based on magnetic vacuum leakage is proposed.Then,a new MFL testing method based on magnetic vacuum leakage is put forward,in which the strong background magnetic field is eliminated,so that the magnetic flux in the ferromagnetic materials to be tested may thoroughly leak at the place of defect into the created magnetic vacuum region without any background magnetic pressure,thus forming a maximum leakage field and being induced by the magneto sensors placed in the region.The feasibility of the proposed principle and method is verified by simulation and experiment.Finally,their advantages are also presented.The proposed principle and method based on near-zero background magnetic field enhance the spatial dimension and intensity of the magnetic leakage field of defects,resulting in an increase of lift-off distance of magneto sensors and a real long-distance and non-contact inspection.Additionally,the information distortion of defects,magnetic noise and the phenomenon of failure of magneto sensors beyond saturated status are reduced or eliminated.Summarily,the proposed principle and method promote the further sufficient application of MFL method.Meanwhile,they also further richen and perfect the theory system of MFL.