基于漏磁检测的桥梁拉索钢丝损伤评估

Assessment of Steel Wire Damages in Bridge Cables Based on Magnetic Flux Leakage Examination

为准确评估桥梁拉索中钢丝的损伤面积和断口宽度,提出基于漏磁检测进行损伤定量评估的方法。该方法通过对轴向漏磁信号沿周向积分进行非线性拟合,根据拟合得到的磁荷量、磁荷间距评估钢丝的损伤面积与断口宽度。以?7-61平行钢丝拉索为例,采用ANSYS软件建立三维电磁有限元模型,对钢丝断丝与坑蚀产生的漏磁场进行模拟,分别采用本文方法和传统方法识别损伤特征量,并识别含噪声的漏磁信号以检验该方法的稳定性。结果表明:根据提出的损伤评估方法得到的磁荷量与损伤面积成正比、磁荷间距随断口宽度等量变化,磁荷量和磁荷间距可用来定量识别钢丝的局部损伤;该方法在钢丝损伤定量评估中具有较高的精度和计算效率,且具有较强的抗噪声干扰能力。

We put forward a quantitative assessment method based on magnetic flux leakage examination is to accurately evaluate the damage area and fracture width of steel wire in bridge cables. In this method, the magnetic charge (MC) and the distance between the dipoles (DBD) were obtained by the nonlinear fitting of the axial component of the magnetic leakage field (MLF) which had been integrated along the circumferential direction around the cable. Then, the damage area and fracture width of steel wire were assessed quantitatively with the MC and the DBD obtained by the nonlinear fitting. Taking a ? 7-61 parallel steel cable as an example, we established a three-dimensional electromagnetic finite element model by using the ANSYS software to simulate the leakage magnetic field caused by wire breakage and pitting corrosion. Furthermore, the damage characteristic values were identified by the proposed method and the traditional method, respectively, and the stability of the proposed method was verified by identifying the leakage magnetic signal containing noise. The results show that, according to the proposed damage assessment method, the MC is proportional to the damage area, and the DBD varies equivalently with the fracture width. The MC and the DBD can be used to quantitatively identify the local damage of steel wire. Besides, the quantitative assessment of steel wire damage based on the proposed method possesses high accuracy, computational efficiency, and strong antinoise ability.