FIBER GRATING SYSTEMS USED TO MEASURE STRAIN IN CYLINDRICAL STRUCTURES

Fiber optic grating systems are described that have been used to measu re strain in cylindrical structures. The applications of these systems to a composite utility cole and to a composite missile body are descr ibed. Composite utility poles have significant advantages with respect to wooden utility poles that include superior strength and uniformity ; light weight for ease of deployment; the ability to be recycled, red ucing hazardous waste associated with chemically treated wooden poles; and compatibility with embedded fiber optic sensors, allowing structu ral loads to be monitored. Tests conducted of fiber optic grating sens ors in combination with an overcoupled coupler demodulation system to support structural testing of a 22-ft composite pole are reported. Mon itoring strain in composite missile bodies has the potential to improv e the quality of manufactured parts, support performance testing, and enhance safety during long periods of storage. Strain measurements mad e with fiber optic grating and electrical strain gauges are described. (C) 1997 Society of Photo-Optical Instrumentation Engineers.