NDE OF ADHESIVE BONDS

THE OVERALL GOAL OF THIS RESEARCH IS TO DEVELOP AN INNOVATIVE NONDESTRUCTIVE (NONINVASIVE) INSPECTION TECHNIQUE THAT CAN DETERMINE WHETHER OR NOT DURABLE ADHESIVE BONDS HAVE BEEN FORMED IN RUBBER-TOMETAL JOINTS AND WHETHER A BOND THAT HAS BEEN EXPOSED TO USE CONDITIONS CONTAINS ITS INTEGRITY. THE PHASE I EFFORT WILL IDENTIFY, DESCRIBE AND EVALUATE THE CONDITIONS FOR EXCITING BOND SENSITIVE ACOUSTIC WAVES, IN PARTICULAR LAMB WAVES, IN RUBBER/METAL LAMINATES RELEVANT TO NAVY APPLICATIONS AND ASSESS THE SENTITIVITY OF WAVE PARAMETERS TO VARIOUS DEGREES OF ADHESION BETWEEN THE MATERIALS. SPECIFIC TECHNICAL OBJECTIVES ARE: 1) TO DETERMINE THE THICKNESS-TOWAVELENGTH LIMIT FOR EXCITATION OF LEAKY LAMB (PLATE) WAVES (THE THICKNESS OF THE ADHERENDS AS WELL AS THE ADHESIVE LAYER WILL BE EXAMINED); 2) TO APPLY EXISTING THEORIES OF WAVE EXCITATION AND PROPAGATION IN LAYERED MEDIA TO BONDED RUBBER-TO-METAL STRUCTURES; 3) TO IMPLEMENT A QUANTIFIABLE METHOD FOR PRODUCING DIFFERENT DEGREES OF BOND ADHESION IN RUBBER/METAL LAMINATES; AND 4) TO DETERMINE THE SENSITIVITY LIMITS OF LEAKY LAMB WAVE METHODOLOGY TO INITIAL BOND QUALITY AND TO CHANGES IN BOND QUALITY, WHERE QUALITY IS DEFINED BY A MEASURE OF ADHESION. ACCELERATED AGING WILL BE EMPLOYED TO EVALUATE ENVIRONMENTAL EXPOSURE EFFECTS.