基于第一性原理管道弱磁应力内检测机理研究

The pipeline stress internal detection is a frontier issue in the international pipeline internal detection technology field. The weak magnetic test technology has the advantage of non-contact and dynamic detection, and is practical significant to the pipeline stress damage internal detection. However, the magnetomechanics relationship is hard to explain the generation mechanism on the weak magnetic signal on the stress concentration areas under geomagnetic field by classic mechanics and magnetic. Thus, the existing theoretical research results can only explain part of the magnetomechanical phenomenon, but cannot precisely analysis the mechanism of pipeline stress non-contact, dynamic and continuous weak magnetic internal detection. With the background of the weak magnetic stress internal detection of the long-distance oil and gas pipeline, the research contents of this project are shown below: (1) Based on the first principle algorithm, the mechanism of weak magnetic internal detection for pipeline stress is studied, and the generation process of the weak magnetic signal on the stress concentration area is explored. (2) The propagation characteristics of the weak magnetic stress signal in different mediums are calculated and analyzed, and the mathematics model of the magnetomechanics for non-contact dynamic detection is built. (3) To verify the correctness of the theoretical model, the relationship between the pipeline stress concentration area and the weak magnetic dynamic signal is systematic studied. Moreover, the theoretical research approach of the pipeline weak magnetic internal detection is established. The research results of this project will promote the scientific application of the weak magnetic stress testing technology in the pipeline stress internal detection field.

管道应力内检测是国际管道内检测技术领域前沿课题。弱磁应力检测技术支持非接触、动态在线检测，对管道应力损伤的内检测具有切实可行的意义。但是，经典力学和磁学很难建立磁力学关系来说明地磁场环境下，应力集中区域微弱磁信号的产生机理；现有的理论研究成果仅能解释部分磁力学现象，无法对管道弱磁应力非接触、动态、连续内检测机理做出准确分析。本项目以长输油气管道弱磁应力内检测为研究背景，拟研究内容包括: （1）采用第一性原理计算方法研究管道弱磁应力内检测机理，探索应力集中区微弱磁信号的产生过程。（2）计算分析弱磁应力信号在不同介质中的传播特性，建立非接触、动态内检测磁力学数学模型。（3）系统实验研究管道应力集中区与弱磁动态内检测信号的对应关系，证明理论模型的正确性，建立管道弱磁应力内检测理论研究方法。项目研究成果将推动弱磁应力检测技术在管道应力内检测领域的科学应用。

管道应力内检测是国际管道内检测技术领域前沿课题。弱磁应力检测技术支持非接触、动态在线检测，对管道应力损伤的内检测具有切实可行的意义。但是，经典力学和磁学很难建立磁力学关系来说明地磁场环境下，应力集中区域微弱磁信号的产生机理；现有的理论研究成果仅能解释部分磁力学现象，无法对管道弱磁应力非接触、动态、连续内检测机理做出准确分析。本项目以长输油气管道弱磁应力内检测为研究背景，采用第一性原理计算方法研究管道弱磁应力内检测机理，深入研究应力集中区微弱磁信号的产生过程；计算分析弱磁应力信号在不同介质中的传播特性，建立非接触、动态内检测磁力学数学模型；系统实验研究管道应力集中区与弱磁动态内检测信号的对应关系，证明理论模型的正确性，建立管道弱磁应力内检测理论研究方法。在本课题资助下，课题组研制出内检测实验样机，其各项指标为：工作压力≤10Mpa，工作时间≤100h，最大里程≤300km，运行速度在 0.3-5Km/h，应力检测精度在±15Mpa。工作温度0-65℃，通过弯头能力>1.5D，允许管道斜接 17°，通过变形能力 15%。可以检测出铁磁性材料塑性变形范围内的应力集中区（磁场分辨率<0.5nT，磁场测量误差<5nT，管壁测量深度为 0～10mm），传感器采样频率＞1KHz。研究成果符合预期指标。本课题针对长输油气管道应力内检测应用领域的难点问题，推动了弱磁应力检测技术在管道应力内检测领域的科学应用。