FIBER-LASER ULTRASOUND DELAMINATION SENSOR FOR COST-EFFECTIVE INSPECTION OF COMPOSITE PARTS

POC PROPOSES A NOVEL METHOD OF LOWERING THE COST AND COMPLEXITY OF LASER-INDUCED ULTRASOUND NONDESTRUCTIVE EVALUATION (NDE). THE PROPOSED TECHNIQUE UTILIZES AN OPTICAL FIBER TO DELIVER LASER "EXCITATION" PULSES, CAUSING RAPID LOCALIZED HEATING, AND GENERATING SHALLOW OUTWARD-PROPAGATING SHOCKWAVES. IN A RADICAL DEPARTURE FROM PREVIOUS NDE SCHEMES BASED ON FIBER OPTIC UTLRASOUND TECHNIQUES, POC PROPOSES TO USE "SIDE-LOOKING" OPTICAL FIBERS TO DETECT THE ULTRASONIC SHOCK-WAVE FRONTS AS THEY TRAVEL THROUGH THE STRUCTURE UNDER TEST. THESE "OPTICAL PICKUPS" COULD BE EMBEDDED IN TAPES THAT WOULD BE EASY TO ATTACH TO, AND REMOVE FROM, THE STRUCTURE OR COMPONENT TO BE EVALUATED. THE TECHNIQUE IS PARTICULARLY SUITED FOR THE RAPID SCANNING OF COMPOSITE PARTS FOR DELIMINATIONS, VOIDS, OR OTHER SURFACE OR SUBSURFACE DEFECTS ANTICIPATED BENEFITS: PHASE I AND PHASE II WILL LAY THE GROUNDWORK FOR THE DEVELOPMENT OF SIDE-LOOKING FIBER LASER ULTRASOUND NDE PRODUCTS. SUCH PRODUCTS WOULD HAVE MANY APPLICATIONS, INCLUDING NDE OF COMPOSITE AIRCRAFT PARTS, "FIELD TESTING" OF AIRCRAFT, AND CIVIL STRUCTURE EVALUATION. BENEFITS OF THIS APPROACH TO NDE INCLUDE "RETROFITABILITY", FLEXIBILITY, SPEED, AND LOW COST.