一种多提离值的金属磁记忆检测方法
陈世利,庞一煜,唐玉莲,等.一种多提离值的金属磁记忆检测方法[J].纳米技术与精密工程,2016,14(6):421-428.
Chen Shili,Pang Yu,Tang Yulian,et al.Metal magnetic memory testing method of multiple lift-off values[J].Nanotechnology and Precision Engineering ,
2016,14(6):421-428(in Chinese).一种多提离值的金属磁记忆检测方法
陈世利,庞一煜,唐玉莲,黄新敬
(天津大学精密仪器与光电子工程学院,天津300072)
摘一要:金属磁记忆检测技术是一种新型的无损检测技术,它利用金属的磁记忆效应来确定构件的缺陷区域.检测
中由于一些构件表面感应磁场信号不平滑,存在与缺陷信号相似的磁场特征和梯度表现,容易造成漏判或误判.为
了区分这两种信号,通过建立磁偶极子模型,分析了缺陷在材料表面或近表面的情况下检测提离值对磁信号的影
响,发现在提离值改变时感应磁场和缺陷漏磁场存在不同的表现.根据这一现象,提出多提离值检测方法进行精确
定位.通过对钢板进行实验验证了该方法的有效性.
关键词:金属磁记忆;磁偶极子模型;提离值;定位方法
中图分类号:TG115.28一一一文献标志码:A一一一文章编号:1672-6030(2016)06-0421-08
一一收稿日期:2016-02-23.一一基金项目:国家自然科学基金资助资助项目(61473205);天津市科技兴海资助项目(KJXH2013-06);天津市科技支撑计划资助项目(14ZCZDGX00003).一一作者简介:陈世利(1973 一),男,博士,副教授.通讯作者:庞一煜,pangyu0@https://www.wendangku.net/doc/a69993538.html,.Metal Magnetic Memory Testing Method of Multiple Lift-Off Values
Chen Shili,Pang Yu,Tang Yulian,Huang Xinjing
(School of Precision Instrument and Opto-Electronics Engineering,Tianjin University,Tianjin 300072,China)Abstract :Metal magnetic memory (MMM)testing technique is a novel nondestructive technology that tests the defects of ferromagnetic material utilizing magnetic memory effect.Sometimes the induced mag-
netic field on the material surface is not smooth,and the magnetic signals and gradient features of the non-defects are similar to those of the defects,which easily leads to misjudgment and omission.To distin-guish these two signals,the influence of lift-off values is analyzed by building a magnetic dipole model.
Results show that changes of lift-off values have different influences on induced magnetic signals and defect magnetic signals when the defect is on or near the surface of the material.A multiple lift-off values method is correspondingly proposed to accurately position defects and is verified through experimental results.Keywords :metal magnetic memory;magnetic dipole model;lift-off value;positioning method
一一金属磁记忆(metal magnetic memory,MMM)检测法是以Doubov 为代表的俄罗斯学者于20世纪90年
代提出的[1].作为新型的无损检测技术,它对构件失效和疲劳损伤有早期诊断的效果[2],并且相对于其他无损检测方法更加方便快捷[3],因此该理论一经提出便立即得到国际社会的普遍重视.
由铁磁学可知铁磁类金属材料的基本特点是自发
磁化,在应力载荷和外部磁场的作用下可以改变其自发磁化矢量取向分布和磁畴结构,从而改变材料磁特性.当铁磁材料存在应力集中或裂纹等缺陷后,局部磁导率会降低,缺陷区域会形成高磁阻区,地磁场原本均匀的磁力线通过该处时会产生聚焦或畸变,由于金属和空气存在的磁导率差异会使内部的磁场在缺陷处 泄漏 到工件表面.通过检测铁磁材料表面的漏磁场万方数据