NONDESTRUCTIVE EVALUATION OF ADHESIVE BONDS IN COMPOSITE MATERIALS

ADHESIVELY JOINED STRUCTURES ARE A COMMON FEATURE OF MANY MILITARY, COMMERCIAL, AND MEDICAL APPLICATIONS. THESE MAY EMPLOY COMPOSITE TO COMPOSITE (E.G. LAMINATED PANELS OR FIBER/RESIN SKINS ON NONMETALLIC HONEYCOMB) AND/OR COMPOSITE TO METALLIC (E.G. FIBER/RESIN SKINS ON ALUMINUM HONEYCOMB) ADHERENDS. STRUCTURES ARE ALSO MADE OF SEGMENTS WITH LOCALLY TAILORED PROPERTIE WHEREIN THE FINAL REULT DEPENDS UPON BONDS BETWEEN THE SEGMENTS. YET NO FULLY SATISFACTORY METHOD OF INSPECTION FOR BONDS EXISTS (STONE, 1986). THIS SHORTFALL HAS A GROWING INFLUENCE, ESPECIALLY IN THE TESTING OF ADHESIVE REPAIRS TO COMPOSITE STRUCTURES AS THE USE OF COMPOSITE MATERIALS PROLIFERATE. PROPERLY PERFORMED, ADHESIVE REPAIRS ARE BETTER THAN MECHANICAL REPAIRS IN SUCH STRUCTURES (KELLY, 1984). THE PRESENT PROPOSAL ADDRESSES THE PROBLEM OF BOND TESTING WITH A NEW METHOD THAT IS ESPECIALLY SUITABLE FOR HIGH SPEED SCREENING OF BONDED STRUCTURES. PHASE I IS A PROOF OF PRINCIPLE FOR DETECTION OF BOND DEFECTS IN THE MATERIALS CITED ABOVE WHEREAS PHASE II INCLUDES DEFECT LOCALIZATION PLUS LARGE SCALE TESTING.