新型脉冲漏磁传感器的仿真设计与实验研究

在对带保温层管道进行检测时,由于保温层的隔离作用使得传统的电磁无损检测方法感生的磁场在传播到管道表面时已衰减的非常微弱,因此,对带保温层管道中腐蚀缺陷的检测是无损检测领域的一个难点.脉冲漏磁方法由于结合了脉冲检测频率丰富以及漏磁检测适于铁磁性管道检测的优势,因而采用脉冲漏磁技术对管道腐蚀缺陷进行了检测.在分析了脉冲漏磁检测原理的基础上,仿真分析了4种不同结构的脉冲漏磁传感器沿管道表面和管壁的磁场分布以及对不同厚度保温层的检测能力,仿真结果表明带聚磁板的模型具有较好的检测能力.最后,采用实验的方法研究了这种模型传感器对腐蚀缺陷深度的定量能力,实验结果表明该传感器可以很好地实现对腐蚀缺陷深度的定量检测.

Simulation Design and Experimention Research on A New Type of Pulsed Magnetic Flux Leakage Sensor

In the course of testing the insulated pipeline, because of the insulation of the insulating layer, the magnetic field generated by the traditional electromagnetic nondestructive testing technique will be badly attenuated when diffusing to the surface of pipeline. So detecting the corrosion in the insulated pipeline is a crux in nondestructive testing (NDT). Pulsed magnetic flux leakage (PMFL) technique is adopted to detect the corrosion in the insulated pipeline because it combines the advantages of richness frequency components of pulsed eddy current testing and the superiority of the magnetic flux leakage technique adapted to the inspection ferromagnetic pipeline together. Based on analyzing the principle of PMFL and by using finite element method, the distribution of magnetic field along the pipeline surface and pipeline wall, and the detection abilities of four different sensor models to the insulated layers in different thickness are studied. The result of simulation shows that the model with the core in both sides of the exciting coil has a better testing ability. Finally, the performances of this sensor are investigated by experiment; the result shows that this sensor can be used to perform quantitative detection of corrosion depth.