Early Detection of Corrosion in Steel Cables by Magnetoelastic Techniques

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High tensile steel wires have structural applications as individual wires, or as tendons, cables or ropes. Typical structures include pre-tensioned and post-tensioned concrete bridges and buildings, cable-supported bridges and anchors in ground engineering. Structures and facilities exposed to the ambient deteriorate and eventually wear out or become unsafe. Understanding when to replace them and how to prolong their useful lifetimes is a critical issue. The objective of this investigation is to develop a magnetoelastic nondestructive technique that would detect corrosion early, and quantify its progress.The magnetoelastic technique is based upon the dependence of the magnetic properties of structural steels on the state of stress and the magnetic permeability is the property that has been used as the parameter to precisely measure the internal stresses. It is recognized that high vibrations and fatigue, coupled with the existing stress state in these cables, are factors that can influence the progress and perhaps the initiation of corrosion in these cables. Hence the corrosion assessment will be monitored by how the magnetoelastic properties are altered by the onset of corrosion. To confirm the performance of the magnetoelastic sensor for early corrosion detection, two electrochemical techniques, DC electrochemical polarization and electrochemical impedance spectroscopy, will be used. The impact of the proposed investigation will be the development of a nondestructive technique for structural health monitoring and life extension. This will benefit society by improving the safety of bridges and other civil structures.