NDI OF COMPOSITE STRUCTURAL MATERIALS BY GAMMA SCATTER SENSING

WITHOUT EFFECTIVE NONDESTRUCTIVE INSPECTION (NDI) MENTHODS, STRUCTURES EMPLOYING COMPOSITE MATERIALS MUST RELY ON LARGE DESIGN MARGINS OF SFETY AND EXPENSIVE INDIVIDUAL COMPONENT PROOF TESTING. OBJECTIVE OF THE PROPOSED PHASE I RESEARCH IS TO REMEDY THIS WITH GAMMA RAY SCATTERING COUNTING, A FORMOF RADIOMETRY WIDELY USED TO MEASURE THICKNESS AND COMPOSI- TION OF EMPHASIS ON DEVELOPING A PORTABLE SYSTEM CAPABLE OF CHARACTERIZING DEFECTS IN LAMINATES OF VARYING THICKNESS. PENDING THE OUTCOME OF THESE TESTS, A PROTOTYPE INSPECTION DEVICE WILL BE DEVELOPED AND TESTED IN PHASE II. UNLIKE CONVENTIONAL RADIOGRAPHY OR RADIOMETRY, GAMMA SCATTERREQUIRES ACCESS TO JUST ONE SURFACE, AND THROUGH PROPER COL-LIMATION CAN BE MADE TO IGNORE SURFACE FEATURES AND SENSE ONLY DEFECTS INSIDE A COMPOSITE STRUCTURE. IT CAN BE EX- TREMELY RUGGED; DETECTORS AND ELECTRONICS SIMILAR TO THOSE REQUIRED FOR A HAND-HELD INSPECTION UNIT HAVE BEEN SUCCESS- FULLY BOOSTED INTO SPACE. OTHER POTENTIAL USES INCLUDE DETECTING INCIPIENT CRACKING OR CORROSION DAMAGE IN STRUC- TURES ALREADY IN USE.