The Development of Robust Structural Health Monitoring Sensors Utilizing TRIP Steel

The feasibility of using the inherently smart properties of transformation-induced plasticity (TRIP) steels as a basis for low cost, robust smart structural health monitoring sensors has been investigated. These steels undergo an irreversible strain-induced phase transformation from paramagnetic austenite to ferromagnetic martensite. Specific needs were identified in the geotechnical industry, and a primary aim of the project was the development of a load cell based on this technology. Cast TRIP steel alloys were designed and tested for their transformation performance during deformation. The response of the phase transformation was also studied under various environmental and loading conditions. The inaccuracies accumulated under unknown environmental and loading conditions were found to be substantial but not excessive for some applications, where other characteristics such as cost and reliability are more important. Results point to potential methods for the reduction of the inaccuracies. Prototype load cells were built and tested, and one variation was installed in a suspension bridge.