Corrosion Sensing and Degradation Detection for Structural Health Monitoring

Corrosion Health Monitoring systems and Prognostics are key elements in assuring the performance and reliability of high value, critical structures.  Analatom is developing a multiplexed Structural Health Monitoring (SHM) system that obtains data from a variety of sensors, including its MEMS micro Linear Polarization Resistance (µLPR) corrosion and strain sensors, in a package a few mils thick combined with a TI MSP430 microcomputer performing real-time intelligent algorithms to detect, monitor, and predict corrosion rates.  The MEMS sensors can be permanently installed on a high-value structure such as a building, bridge, or aircraft, and are connected to a data acquisition node.  Data transmission uses a ZigBee wireless self-organizing network that has low power requirements.  This enables SHM monitoring of local regions for negative impact arising from multiple, interacting states of degradation, and early alerting that preventative maintenance needs to be undertaken to prevent future expensive repairs and/or replacement.

The µLPR sensors have been installed on a mock-up bridge cable at Columbia University as a part of large project, sponsored by FHWA, on the development of a corrosion monitoring system for main cables of suspension bridges.  These sensors were extensively tested in a QFog 1100 Accelerated Corrosion Chamber, before being placed inside a full-scale mock-up of a suspension bridge cable.  This cable mock-up has a diameter of 21 in. and its length reaches 34 ft.  8 µLPR sensors were embedded inside the cable which was then placed in a large environmental chamber and subjected to accelerated corrosion conditions for one year.  During this time, the µLPR sensors recorded corrosion rate measurement at 8 different locations inside the cable, showing excellent agreement with the temperature measurements.  The next step on the project will consist in the deployment of such sensors at two locations on the main cable of the Manhattan Bridge in NYC.