PORTABLE ELECTRO-OPTIC NDT TECHNIQUE FOR SOLID ROCKET MOTORS

THE DETECTION AND CHARACTERIZATION OF DEFECTS IN SOLID PROPELLANTS, NOZZLES, CONES AND OTHER PROPULSION COMPONENTS ARE OF GREAT IMPORTANCE IN THE MANUFACTURING OF SOLID ROCKET MOTORS. TO IMPLEMENT THE REQUIRED QUALITY CONTROL, PROPER TEST METHODS THAT CAN BE CARRIED OUT AT THE MANUFACTURING SITE MUST BE DEVELOPED. HENCE, THERE EXISTS A NEED TO DEVELOP PORTABLE NDT TECHNIQUES THAT COULD BE RAPIDLY AND CONVENIENTLY USED AT THE FABRICATION SITE. WE PROPOSE THAT SHEAROGRAPHY, AN INTERFEROMETRIC OPTICAL TECHNIQUE THAT HAS MAJOR ADVANTAGES OVER THE MORE CONVENTIONAL APPROACHES, BE USED IN THE DETECTION AND CHARACTERIZATION OF DEFECTS SUCH AS SURFACE AND SUBSURFACE CRACKS AND NEAR SURFACE VOIDS ON THE INNER SURFACE OF THE PROPELLANTS IN SOLID ROCKET MOTORS. PREVIOUS WORK HAS SHOWN THAT THIS TECHNIQUE CAN BE EMPLOYED IN THE NON-DESTRUCTIVE DETECTION AND CHARACTERIZATION OF THESE TYPES OF FLAWS. IT IS A NONCONTACT TECHNIQUE, INVOLVES RELATIVELY INEXPENSIVE EQUIPMENT AND NEEDS NO ELABORATE DATA ACQUISITION PROCEDURES. UNLIKE THE CONVENTIONAL INTERFEROMETRIC TECHNIQUES, SHEAROGRAPHY IS IMMUNE TO ENVIRONMENTAL VIBRATIONS. HENCE, THE SHEAROGRAPHIC NON-DESTRUCTIVE EXAMINATION METHOD CAN BE AN IDEAL CANDIDATE FOR IMPLEMENTATION AS A PORTABLE ON-SITE INSPECTION TOOL.