油气长输管道裂纹磁致伸缩式导波检测技术基础研究

项目名称： 油气长输管道裂纹磁致伸缩式导波检测技术基础研究

项目编号： No.50875077

项目类型： 面上项目

立项/批准年度： 2009

项目学科： 电工技术

项目作者： 宋小春

作者单位： 湖北工业大学

项目金额： 32万元

中文摘要： 由于裂纹类缺陷会引起在役油气长输管道局部复杂的应力变化，因此，课题首先探讨了复杂应力作用下的磁弹性耦合机理。基于磁致伸缩材料的非线性本构方程，理论推导了力磁耦合作用下磁致伸缩应变、磁致伸缩换能效率和磁致伸缩力的计算模型，仿真分析了其相互作用关系和影响规律。通过求解铁磁性管道中磁致伸缩导波的波动方程，得到了空心圆管中导波的频散特征方程，研究了外加应力对不同模态磁致伸缩导波频散特性的影响关系，描述了磁致伸缩导波在裂纹扩展区的声场特性和周向传播理论。在此基础上，构建了油气管道裂纹磁致伸缩式导波激励和接收传感器结构模型，分析了传感器结构参数对偏置磁场均匀性的影响，优化了传感器结构，完成了一套检测实验系统，并针对国产φ2×.7mm天然气长输管道的表面裂纹开展了检测实验研究。研究和实验结果表明，磁致伸缩式导波检测技术能够实现对大口径油气管道裂纹类缺陷的快速检测，其有望成为我国油气长输管道非接触、长距离、快速质量检测的重要手段。

中文关键词： 裂纹；磁致伸缩；导波；力磁耦合；油气管道

英文摘要： Since the crack or crack-like defect, occurred in the oil and natural gas pipeline, could often cause local stress change, the magnetoelastic coupling mechanism under complicated stresses have been investigated firstly. Based on the nonlinear constitutive equations of magnetostrictive materials, the calculational model for magnetostrictive strain, magnetostrictive transducing efficiency and magnetostritive force under magnetic-elastic coupling were derived theoretically, and their relationships and the effect law were simulated and analyzed. Then, the dispersion equation for guided waves with different modes were established by solving the wave equations of guided waves in a hollow cylinder, and the effects of applied stresses on dispersion characteristics for magnetostrictive guided waves were studied, the sound field characteristic and the propagation theory of the circumferential wave were described while guided-waves passing through the crack propagation zone. Finally, the structure model of transducer to excite and receive magnetostrictive guided-waves were established, the influences of the magnetic circuit structure of the transducer on the uniformity of bias magnetic field were studied, and a magnetostrictive guided wave testing system, used to inspect large diameter pipelines, was developed. Moreover, some experiments to detect axial crack-like defects for pipelines with φ2×.7mm were completed by the system. The experimental results have demonstrated that the method is capable of detecting the axial crack or crack-like defects of pipelines rapidly, and may become an important means to realize the long-distance, non-contact and rapid inspection for oil and gas pipelines.

英文关键词： crack; magnetostriction; guided wave; magnetic-elastic coupling; pipelines