Not Available

Period of Performance: 01/01/2001 - 12/31/2001


Phase 1 SBIR

Recipient Firm

InfraTech Inc.
13429 Fairland Park Drive
Silver Spring, MD 20904
Principal Investigator


This Small Business Innovation Research (SBIR) Phase I project will investigate the feasibility of direct measurement of live forces in civil infrastructures such as the cables of cable-stayed bridges, using a new magnetoelastic sensor. Knowledge of stress conditions is essential for detection of stress changes due to fatigue, overload, or corrosion and thereby, to prolong a structure's service life and/or to improve its performance. Knowledge of the stress state is also valuable for evaluating the structural integrity of cables during and after natural disasters such as earthquakes or severe winds. These measurements should be made rapidly and cost-effectively. Conventional sensors, such as strain gages and accelerometers, do not respond to stress directly. The new magnetoelastic sensor depends on the magnetic properties of structural steels in a stressed state. The sensing circuit is external to the steel, simple to install, and sensitive to in-situ stress with an error less than 3%. A magnetic property called the anhysteresis curve is measured.