LASER GENERATED SURFACE ACOUSTIC WAVES FOR FLAW DETECTION IN TRANSPORTATION SYSTEMS.

TRANSPORTATION SYSTEM STUDIES REQUIRE IN-SERVICE INSPECTION USING NONDESTRUCTIVE EVALUATION (NDE) TECHNIQUES FOR FLAW DETECTION AND CHARACTERIZATION. IN CASES WHERE SUCH DEFECTS ARE SMALL COMPARED WITH THE THICKNESS OF THE SECTION, ULTRASONIC METHODS ARE CONSIDERED TO BE THE MOST SUITABLE. IT WOULD BE IDEAL TO MAKE SUCH MEASUREMENTS REMOTELY WITH A SYSTEM COMBINING THE STRONG FEATURES OF ULTRASONICS WITH LASER TECHNOLOGY. THIS PROPOSAL SUGGESTS THE USE OF LASER GENERATED ULTRASOUND AS THE BASIS FOR AN NDE SYSTEM FOR USE IN TRANSPORTATION-RELATED COMPONENTS. THE OBJECTIVES OF THE RESEARCH PROGRAM ENCOMPASS THE DEVELOPMENT OF A LASER GENERATION AND A LASER DETECTION SYSTEM WITH THE ESTABLISHMENT OF THE RELATIONSHIP BETWEEN LASER PROPERTIES AND MATERIAL PROPERTIES IN RELATION TO LAUNCHING OF ACOUSTIC WAVES FOR USE IN FLAW DETECTION. A COMPREHENSIVE SET OF CONTROLLED EXPERIMENTS WILL BE CONDUCTED AND AN OPTIMIZATION OF A SELECTED PROOF-OF-CONCEPT SYSTEM WILL BE UNDERTAKEN. THE WORK EFFORT ALSO CALLS FOR EVALUATION OF LASER DETECTOR SYSTEMS AND ANALYSIS OF FIBER OPTICS AS A CONDUCTOR OF LASER LIGHT IN COMPLEX GEOMETRIES.