AN EDDY-CURRENT MODEL AND INVERSION ALGORITHM FOR NONDESTRUCTIVE EVALUATION OF ADVANCED COMPOSITES

THE PROPOSED RESEARCH PROBLEM IS TO DEVELOP A SENSOR, TOGETHER WITH A MATHEMATICAL ALGORITH, THAT WILL ALLOW THE THREE- DIMENSIONAL QUANTITATIVE EDDY-CURRENT NONDESTRUCTIVE EVALUTION OF MATERIALS AND STRUCTURES. THE APPROACH THAT WE PROPOSE IS BASED ON, AND EXTENDS WORK ON TWO-DIMENSIONAL EDDY-CURRENT NDE THAT THAT HAS ALREADY BEEN PERFORMED BY ANALYTIC, INC. THAT WORK IS BRIEFLY REVIEWED. THE TECHNICAL OBJECTIVES OF THE PROPOSED RESEARCH ARE: (1) DETERMINE SUITABILITY OF HALL-EFFECT PROBES FOR SENSING EDDY-CURRENTS, (2) DETERMINE OPTIMUM ARRAY OF HALL-EFFECT PROBES FOR THE SENSOR,(3) DETERMINE SUITABILITY OF DISTRIBUTED WINDINGS AND\OR PHASED-ARRAYS FOR SENSING, OR INDUCING, EDDY-CURRENTS, AND (4) EXTEND THE ALGORITHM FOR RECONSTRUCTING FLAWS IN TWO-DIMENSIONS TO THREE-DEMENSIONS. THESE OBJECTIVES ARE MET BY ANALYZING A MODEL SENSOR, WHICH IS DESCRIBED. THE ANALYSIS IS BASED ON CERTAIN INTEGRAL RELATIONS FOR EDDY-CURRENTS.THESE INTEGRALS ARE DERIVED FROM FUNDAMENTAL ELECTROMAGNETIC THEORY, AND ARE THE FOUNDATION AND ARE THE FOUNDATION FOR OUR INVERSION TECHNIQUE.