Development of a Remote Coil Magnetoelastic Stress Sensor for Monitoring Steel Cables and Tendons

一种用于监测钢索和钢腱的远距离线圈磁弹性应力传感器的研制摘要尽管斜拉桥越来越受欢迎，但没有准确或简单的方法可以直接测量斜拉索中的应力（力）。力的测量对于监测过度的风或交通载荷、测量地震事件后出现的再分布力以及通过横截面损失检测腐蚀非常重要。 计划开发一种远程（便携式）磁致弹性传感器，用于直接测量钢索和钢筋束中的应力。芝加哥的伊利诺伊大学开发了一种基于圆柱螺线管几何形状的磁致弹性传感器，适用于在施工或现场缠绕现有缆索时安装。该技术是基于结构钢的磁性能与应力状态直接相关的依赖性。通过使钢经受脉冲或周期性磁化场来测量磁性。通过围绕或邻近钢的电路的磁通量的变化允许测量磁特性。 在-40（F）至140（F）的温度范围内，通常使用低于弹性极限的不同尺寸的传感器实现1%以内的精度（相对于测力传感器）。这些传感器已在多个项目的施工期间接受现场测试。本项目将研究将磁致弹性测量原理扩展到新的传感电路的途径，该传感电路不需要将其缠绕在电缆上。它是便携式和可重复使用的。这是非常可取的执行应力测量使用这种线圈的几何形状在后屈服制度的损坏评估电缆由于意外的负载。

Development of a Remote Coil Magnetoelastic Stress Sensor for Monitoring Steel Cables and TendonsABSTRACTDespite the increasing popularity of cable-stayed bridges, no accurate or simple method is available for directly measuring the stresses (forces) in the cable stays. The measurement of the forces is important for monitoring excessive wind or traffic loadings, to gage the redistribution forces present after seismic events, and for detecting corrosion via loss of the cross section. It is planned to develop a remote (portable) magnetoelastic sensor for the direct measurement of stress in steel cables and tendons.A magnetoelastic sensor based on a cylindrical solenoidal geometry, which is suitable for installation at the time of construction or winding in-situ for existing cables has been developed at the University of Illinois at Chicago. The technique is based upon the dependence of the magnetic properties of structural steels directly related to the state of stress. The magnetic properties are measured by subjecting the steel to a pulse or periodic magnetising field. Changes in flux through circuits surrounding or adjacent to the steel allow the magnetic properties to be measured. Accuracy within 1% (against a load cell) in the temperature range of -40 (F) to 140(F) are routinely achieved with different sizes of sensor below the elastic limit. These sensors have been accepted for field testing during the construction of several projects. This project will investigate avenues to extend the magnetoelastic measurement principles to a new sensing circuit which does not require winding it around the cable. It is portable and reusable. It is highly desirable to perform the stress measurement using this coil geometry in the post-yield regime for damage assessment of cables due to unanticipated loadings.