CONTINUOUS ON-BOARD NON-DESTRUCTIVE MONITORING OF DEGRADATION IN STIFFNESS AND STRENGTH OF FIBER COMPOSITES

COMPOSITE MATERIALS ARE BEING IMPLEMENTED INTO A VARIETY OF CRITICAL AEROSPACE APPLICATIONS. DAMAGE DEVELOPMENT OCCURS TO THESE COMPOSITES DUE TO CYCLIC LOADING FATIGUE AND ENVIRONMENTAL EFFECTS. CONDITION MONITORING OF THESE COMPOSITES IS THEREFORE NEEDED IN ORDER TO ASSESS THE COMPOSITE'S STRUCTURAL RELIABILITY. WE PROPOSE THE DEVELOPMENT OF AN IN-SERVICE MICROSENSOR BASED HEALTH MONITORING SYSTEM IN ORDER TO DETERMINE DEGRADATION IN THE COMPOSITE'S STIFFNESS AND STRENGTH PROPERTIES AND PREDICT THE COMPOSITE'S USEFUL REMAINING SERVICE LIFE. IN SITU ANALYSIS TECHNIQUES WILL BE USED TO DETERMINE DEGRADATION IN COMPOSITE/STRUCTURAL STIFFNESS PROPERTIES. STRENGTH DEGRADATION WILL BE DETERMINED THROUGH A RECENTLY DEVELOPED CORRELATION BETWEEN STIFFNESS DEGRADATION AND STRENGTH DEGRADATION. MICROSENSORS AND MICROACTUATOR WILL BE CONSIDERED AS LOW COST WEIGHT CANDIDATES FOR AN IN-SERVICE SYSTEM. IMPLEMENTATION SCHEMES DEVISED FOR THE PROPER IMPLEMENTATION OF THE SENSORS INTO THE COMPOSITES WILL ALSO BE CONSIDERED IN PHASE I.