桥梁拉索金属面积损失的磁通检测信号特征

Characteristic of Signal from Magnetic Flux Examination of Loss of Metallic Area in Bridge Cables

摘要:

基于磁路分析法研究桥梁拉索磁通检测与定量评估时缺陷长度对磁通信号的影响，通过模型试验研究磁通信号特征并验证理论分析，采用有限元法分析缺陷长度效应对缺陷形态、截面损失率、索径、检测设备尺寸等参数的敏感性.结果表明，磁通信号波动值与金属面积损失率成正比，且可能受缺陷长度干扰；钢丝的磁化强度沿拉索径向近似按线性衰减；桥梁拉索中的缺陷长度效应比其他绳索或棒材中更显著，当缺陷比磁头间净距短时忽视该效应将低估损伤程度.

关键词:桥梁; 拉索; 金属面积损失; 磁通检测; 磁路分析; 模型试验; 有限元法

Abstract:

Influence of defect length on the signal output from the magnetic flux (MF) examination of bridge cables for quantitative evaluation was studied. Model experiments were conducted to inspect the characteristics of signal output from the MF examination, and to verify the conclusions from magnetic circuit analysis. Finite element method was used to analyze the sensitivity of the defectlength effect to parameters including the defect morphology, percent loss of metallic area (LMA), cable diameter, size of the test device et al. The results show that fluctuation of the signal from the MF examination of the bridge cable is proportional to the percent LMA, and may be disturbed by the length of flaw; the magnetization intensity of steel wires attenuates approximate linearly along the radial direction of cable; the defectlength effect in bridge cable is more significant than that in steel ropes or rods; when the flaw is shorter than the net distance between the magnets, the damage will be underestimated if the defectlength effect is neglected.

Key words:bridge; cable; loss of metallic area; magnetic flux examination; magnetic circuit analysis; model experiment; finite element method