AN EDDY-CURRENT MODEL FOR THREE-DIMENSIONAL NONDESTRUCTIVE EVALUATION OF ADVANCED COMPOSITES

THE PROPOSED RESEARCH PROBLEM IS TO DEVELOP A MODEL AND AN INVERSION ALGORITHM THAT IS SUITABLE FOR THE THREE-DIMENSIONAL QUANTITATIVE NON-DESTRUCTIVE EVALUATION (NDE) OF ADVANCED COMPOSITE MATERIALS BY USING EDDY-CURRENTS. THE APPROACH THAT WE PROPOSE IS BASED ON, AND EXTENDS, WORK THAT HAS ALREADY BEEN PERFORMED BY ANALYTICS, INC. FOR EDDYCURRENT NDE OF CONVENTIAL METALS. THE TECHNICAL OBJECTIVES ARE TO DETERMINE THE FEASIBILITY OF USING MULTIFREQUENCIES FOR THIS JOB, TO DETERMINE IN LOCALIZED REGIONS THE FIBER-RESIN RATIO IN GRAPHICS EPOXY AND TO DETERMINE MORE PRECISELY THE TYPES ANOMALIES, WHETHER FLAWS, DELAMINATIONS, BROKEN FIBERS, ETC., THAT CAN BE RECONSTRUCTED BY OUR INVERSION METHOD. THESE OBJECTIVES CAN BE MET BY; (1) APPLYING RIGOROUS ELECTROMAGNETIC THEORY TO DETERMINE A GREEN'S FUNCTION FOR A STRATIFIED HALF-SPACE OF ANISOTROPIC COMPOSITE MATERIALS, (2) DETERMINING THE INTEGRAL RELATIONS FOR THE DIRECT AND INVERSE PROBLEMS, USING THE GREEN'S FUNCTION JUST DERIVED, (3) DETERMINING SUITABLE NUMERICAL ALGORITHMS FOR SOLVING THE INVERSE PROBLEM, AND (4) WRITING A COMPUTER PROGRAM TO EXECUTE THE MODEL.