基于双磁场管道复合型缺陷应力信号提取方法研究

缺陷和应力共同存在的复合型缺陷是影响管道安全运行的重要因素之一。双磁场管道内检测法可用于复合型缺陷处应力损伤程度判断，但应力信号提取方法亟待解决。本文将J-A理论中的磁力学关系引入磁荷模型中，解析计算了不同应力、外磁场下复合型缺陷磁信号，建立基于双磁场信号比值的复合型缺陷应力信号提取模型，提出比值因子用于缺陷处应力水平的评估，并进行了系统的实验验证。研究结果表明，强磁信号对缺陷处应力大小不敏感，信号主要包括缺陷尺寸信息；弱磁信号对缺陷处应力大小敏感，信号包括缺陷尺寸信息和缺陷处应力信息。提出的比值因子可反映缺陷处应力情况，弱磁场强度较低时，比值因子随缺陷处应力的平均变化率大于9%,随着弱磁场强度的增加，比值因子随应力变化幅度变小。

Research on the stress signal extraction method of pipeline composite defect based on dual magnetic field

The composite defect existing together with the stress is one of the important factors which affects the safe operation of pipeline. The dual magnetic field method can be used to judge the degree of stress damage at composite defects. But the stress signal extraction method needs to be solved urgently. In this article, the magnetomechanical relationship in the J-A theory is introduced into the magnetic charge model. The magnetic signals of composite defects under different stress and external magnetic field are analyzed and calculated. The stress signal extraction model of composite defects based on the ratio of dual magnetic field signals is formulated. The ratio factor is proposed to evaluate the stress level at the defect, and the systematic experimental evaluation is carried out. The results show that the strong magnetic signal is not sensitive to the stress at the defect, and the signal mainly includes the defect size information. The weak magnetic signal is sensitive to the stress at the defect, and the signal includes defect size information and stress information at the defect. The ratio factor can reflect the stress at the defect. When the weak magnetic field intensity is low, the average change rate of the ratio factor with the stress at the defect is larger than 9% . With the increase of weak magnetic field intensity, the variation range of ratio factor with stress decreases.