HIGH TEMPERATURE MEASUREMENT USING SAPPHIRE OPTICAL FIBER SENSORS FOR NASP MATERIAL TESTS

THE MEASUREMENT OF STRAIN AT HIGH TEMPERATURE IN CANDIDATE NASP MATERIALS IS REQUIRED IN ORDER TO MONITOR MATERIAL RESPONSE UNDER SIMULATED OPERATIONAL CONDITIONS AND TO DESIGN EFFICIENT HOT AEROSPACE STRUCTURES. CONVENTIONAL CONTACT RESISTIVE FOIL STRAIN GAGES ARE NOT SUITABLE FOR HIGH TEMPERATURE MEASUREMENTS DUE TO REDUCED ACCURACY, REQUIREMENT FOR FREQUENT CALIBRATION, AND DEBONDING FROM TEST MATERIALS. FIBER AND SENSOR TECHNOLOGIES, INC. PROPOSES TO DEMONSTRATE THE FEASIBILITY OF STRAIN MEASUREMENT AT TEMPERATURES UP TO 3000¿F ON NASP CANDIDATE MATERIALS USING SAPPHIRE FIBER STRAIN GAGES IN BOTH STATIC AND DYNAMIC TEMPERATURE TEST CONDITIONS, AND TO CONSIDER RELATED IMPLEMENTATION ISSUES SUCH AS SENSOR ATTACHMENT AND SIGNAL PROCESSING. THE 3600¿F MELTING TEMPERATURE OF OPTICAL QUALITY SAPPHIRE FIBERS SUITABLE FOR FIBER SENSORS, AND THE INHERENT IMMUNITY OF FIBER OPTICAL SENSORS TO ELECTROMAGNETIC INTERFERENCE AND GROUND LOOPS MAKE SAPPHIRE FIBER-BASED STRAIN SENSORS PARTICULARLY ADVANTAGEOUS.