Fan Xiangfeng, Yang Lijian
School of Information Science and Engineering, Shenyang University of Technology, Shenyang 110870, China.
Sensors (Basel). 2024 Aug 5;24(15):5074. doi: 10.3390/s24155074.
Weak magnetic detection technology can detect stress concentration areas in ferromagnetic materials. However, the stress non-uniform characteristics of pipeline welds lead to significant differences in stress distribution range and values between inner wall welds and outer wall welds. This discrepancy makes it crucial to further evaluate the impact of stress non-uniformity on magnetic signals. To study the magnetic signal characteristics under the influence of residual stress in weld seams, a magneto-mechanical analytical model was established based on the magnetic charge theory and the distribution characteristics of residual stress in the weld seam. The magneto-mechanical relationship and magnetic signal distribution characteristics at the inner and outer wall welds of the pipeline are calculated. Furthermore, the effects of different excitation intensities on the amplitude growth characteristics of magnetic signals are analyzed and compared. To verify the analysis model, weld detection experiments with different excitation intensities were designed. The results show that both the peak-to-valley values of the normal component and the peak values of the tangential component of the outer wall weld are lower than those of the inner wall weld. Conversely, the peak-to-valley width of the normal component and the peak width of the tangential component are greater than those of the inner wall weld. Additionally, the rate of increase in weak magnetic signal amplitude decreases in a first-order exponential relationship with increasing excitation intensity. The average decay rates of the normal and tangential component amplitude growth rates for the inner wall weld are 34.03% and 27.9%, respectively, while for the outer wall weld, they are 31.75% and 28.01%, respectively. This study contributes to the identification and quantitative assessment of weak magnetic signals in inner and outer wall welds.
弱磁检测技术能够检测铁磁材料中的应力集中区域。然而，管道焊缝的应力非均匀特性导致内壁焊缝和外壁焊缝在应力分布范围和数值上存在显著差异。这种差异使得进一步评估应力非均匀性对磁信号的影响至关重要。为了研究焊缝残余应力影响下的磁信号特性，基于磁荷理论和焊缝残余应力分布特性建立了磁-力学分析模型。计算了管道内壁和外壁焊缝处的磁-力学关系及磁信号分布特性。此外，分析并比较了不同激励强度对磁信号幅值增长特性的影响。为验证分析模型，设计了不同激励强度的焊缝检测实验。结果表明，外壁焊缝法向分量的峰谷值和切向分量的峰值均低于内壁焊缝。相反，外壁焊缝法向分量的峰谷宽度和切向分量的峰值宽度大于内壁焊缝。此外，弱磁信号幅值的增长率随激励强度的增加呈一阶指数关系下降。内壁焊缝法向和切向分量幅值增长率的平均衰减率分别为34.03%和27.9%，而外壁焊缝分别为31.75%和28.01%。本研究有助于识别和定量评估内壁和外壁焊缝中的弱磁信号。
