U型ACFM探头精确建模和实验测试

Precise modeling and experimental testing of the U-shaped probe for ACFM

针对当前交流电磁场检测(ACFM)仿真模型的不足,结合ACFM检测原理和数值分析技术,充分考虑U型ACFM探头扫描过程、电磁场数据点检测特点以及检测线圈材料等实际因素,提出了一种新的加入检测线圈的ACFM探头移动精确建模方法,建立工件表面缺陷U型ACFM探头仿真模型,精确分析缺陷感应电磁场信号分布规律以及信号特征量,并设计真实裂纹ACFM检测实验,对实验结果和仿真结果进行信号特征值对比分析,结果表明,仿真所得缺陷信号规律与真实实验结果一致,特征值平均相对误差不超过10%,能够较为精确地反应真实检测结果。采用提出的精确建模方法可以对任意形状、任意尺寸缺陷的U型ACFM检测进行仿真分析和缺陷信号特征提取,以弥补真实人工缺陷ACFM检测缺陷信号特征数据的不足,为U型ACFM探头优化设计以及缺陷量化等反问题研究提供基础数据。

Aiming at the limitation of the current alternating current field measurement （ACFM） simulation model, the detection coil is inducted, and precise numerical model of the ACFM system is built for structure surface cracks detection based on the ACFM principle and numerical analysis. This model fully considers the influence of the scanning process and the material of the detecting coil. Finite element simulation is performed to investigate the rules and characteristics of the electromagnetic signal distributions in regions with defect, and the real crack inspection experiments are designed with the U-shaped probe of the ACFM prototype in laboratory. From comparison analysis, it can be concluded that the defect signal distributions of simulation model is consistent with real experimental result, and the average relative error of characteristics is less than 10% , which can response to the real system test more accurately. The precise model proposed in this paper can simulate all sorts Of defects and extract signal characteristic quantity, which makes up for the deficiency of the defect database of true artificial defects and provides basic data to the study on inverse problems of defects quantitative and probe optimization.