Gao Xiangdong, Li Yanfeng, Chen Tingyan, Gao Perry P, Zhang Yanxi
Appl Opt. 2019 Jan 10;58(2):291-301. doi: 10.1364/AO.58.000291.
To reduce the effect of the nonuniformity of magnetic field excitation on micro-gap weld joint magneto-optical (MO) imaging, a new experimental system based on the Faraday MO effect to detect micro-gap welds (gap width less than 0.1 mm) under nonuniform magnetic field excitation was developed. Horseshoe permanent magnets were used to magnetize the weldment and establish a nonuniform magnetic field at the welding joint. MO images of the micro-gap weld joint were captured using an MO sensor under nonuniform magnetic field excitation. After analyzing the distribution characteristics of the magnetic induction intensity in the weld joint area, a characterization method for the weld zone slope was proposed. The weld zone slope could accurately determine the MO imaging effects under the nonuniform magnetic field. A model based on an error backpropagation (BP) neural network was used to predict the offset of the weld joint center at each moment, and the results performed by BP were utilized to optimize the measured value of the weld joint center. Experimental results show that it can accurately extract the position of micro-gap welds under nonuniform magnetic field excitation.
为降低磁场激励不均匀性对微间隙焊接接头磁光（MO）成像的影响，开发了一种基于法拉第磁光效应的新型实验系统，用于在不均匀磁场激励下检测微间隙焊缝（间隙宽度小于0.1毫米）。采用马蹄形永久磁铁对焊件进行磁化，并在焊接接头处建立不均匀磁场。在不均匀磁场激励下，使用磁光传感器采集微间隙焊接接头的磁光图像。通过分析焊接接头区域磁感应强度的分布特性，提出了一种焊缝区斜率的表征方法。焊缝区斜率能够准确确定不均匀磁场下的磁光成像效果。采用基于误差反向传播（BP）神经网络的模型预测每个时刻焊接接头中心的偏移量，并利用BP得到的结果优化焊接接头中心的测量值。实验结果表明，该系统能够在不均匀磁场激励下准确提取微间隙焊缝的位置。
