OTHER AEROSPACE MATERIALS

A NEW TYPE OF ACOUSTIC MICROSCOPE HAS BEEN DEMONSTRATED BY PROF. B. T.KHURI-YAKUB AT STANFORD UNIVERSITY, WORKING UNDER AN AIR FORCE GRANT. THIS MICROSCOPY UTILIZES SPECIAL WIDE APERTURE ULTRASONIC TRANSDUCERS DESIGNED AND BUILT BY THE PROPOSER, AND MAKES USE OF A SURFACE WAVE EFFECT ON THE SAMPLE UNDER TEST TO ENHANCE SENSITIVITY TO CERTAIN TYPES OF DEFECTS. IMAGES OF SAMPLES OF KEVLAR-EPOXY AND CARBONCARBON COMPOSITES HAVE RESOLVED INDIVIDUAL BROKEN FIBERS, AND TRACED THE STRUCTURE OF CRACKS DOWN INTO THE MATERIAL. SHARP FOCUSSING ALLOWS VIEWING LAYER BY LAYER AS IF PEELING THE LAMINA AWAY. THE MICROSCOPE ALSO HAS DEMONSTRATED GOOD RESULTS ON ADHESIVE BONDED AND DIFFUSION BONDED METAL SAMPLES, AND HONEYCOMB STRUCTURES. WE PROPOSE TO ACQUIRE A LICENSE FROM STANFORD, TO DEVELOP THIS MICROSCOPE AS A COMMERCIAL PRODUCT, AND USE FUNDS FROM THE GRANT, ALONG WITH FUNDS OF OUR OWN TO SETUP A TEST BED SYSTEM AND PERFORM EXPERIMENTS NECESSARY TO QUANTITATIVELY EVALUATE THE PERFORMANCE AND COMMERCIAL FEASIBILITY OF THIS SYSTEM AS A PRODUCT. WE WILL BE EVALUATING RESOLUTION, SENSITIVITY TO VARIOUS TYPES OF DEFECTS, AND DEPTH OF PENETRATION IN VARIOUS TYPES OF SAMPLES. WE WILL ALSO DETERMINE MAXIMUM SCANNING SPEED AND HARDWARE FACTORS AFFECTING SYSTEM COST.