弱磁场作用下的磁偶极子模型建立与分析

利用磁偶极子理论,建立稳恒微弱地磁场作用下管类试件线状缺陷段产生的漏磁场模型.根据磁偶极子空间磁场分布,导出了地磁场下管状工件表面细长缺陷段产生的弱磁场法向分量的计算公式,并且分析了不同纵向磁化强度下,作为磁记忆检测方法重要判据的磁场法向零值线形状及分布特点.研究了管件处于外部弱磁场的缺陷段的位置对表面磁场法向分量零值线分布的影响.结果表明,利用磁记忆方法作无损检测,寻找和定位缺陷段位置时,应该考虑法向分量零值线的这种分布特征.

Model of Magnetic Dipole Established in Weak Magnetic Field

The magnetic leakage field distribution above linear defects of a tube sample under the geomagnetic field was modeled according to magnetic dipole theory.The formula to compute the normal component of the weak magnetic field above the defects was derived based on the spatial distribution of magnetic dipole.The shape and character of the zero line,an important criterion for magnetic memory testing of the normal field is analyzed under different longitudinal magnetization.The results showed that the character of the zero line should be considered when using metal magnetic memory testing method to find and locate the defects.