Magnetic memory stress detection technology has broad application prospects in the field of stress detection in long-distance oil and gas pipelines because it supports non-contact and dynamic on-line detection. However, the magnetic memory signal is weak and susceptible to an external magnetic field. A J-A model is established to quantitatively study the distribution characteristics of the magnetic memory signal in the stress concentration area of the pipeline. In this study, the mathematical model of magnetomechanics of the pipeline is established. The variation law of magnetic memory signal in the stress concentration area with the external magnetic field is calculated and analysed. A systematic experimental study is carried out. The results show that the magnetic memory signal linearly changes with stress in the geomagnetic field, and magnetic memory signal characteristics of circumferential stress with internal pressure is larger than the axial one. The amplitude of the magnetic memory signal in the stress concentration area increases with the increase in magnetic field intensity of the weak magnetic field, meantime the magnetic sensitivity decreases. The magnetic memory signal in the stress concentration area of the pipeline in magnetic saturation is covered by the strong magnetic field resulting in an undetected stress concentration area.

中文翻译：

---

基于电磁力学特性的长输油气管道应力检测技术研究

磁记忆应力检测技术支持非接触式和动态在线检测，因此在长距离油气管道的应力检测领域具有广阔的应用前景。但是，磁存储信号微弱并且容易受到外部磁场的影响。建立一个JA模型，定量研究管道应力集中区域内磁记忆信号的分布特征。本研究建立了管道电磁力学的数学模型。计算并分析了应力集中区域内磁记忆信号随外部磁场的变化规律。进行了系统的实验研究。结果表明，磁记忆信号随地磁场的应力线性变化，磁记忆信号的特征是内应力的周向应力大于轴向应力。应力集中区域的磁记忆信号幅度随弱磁场强度的增加而增大，同时磁灵敏度降低。处于磁饱和状态的管道应力集中区域中的磁存储信号被强磁场覆盖，导致未检测到应力集中区域。