RADIOGRAPHIC LAYER COUNTER FOR COMPOSITES

THE ARMY BALLISTIC HELMET IS A COMPOSITE CONSISTING OF 19 RESINBONDED KELVAR. IT IS TYPICALLY LAID UP IN A PINWHEEL AND CROWN PLY CONFIGURATION. INADVERTANT OMISSION OF LAYERS OR UNDETECTED SHIFTING OF LAYERS DURING THE MOLDING PROCESSES CAN REDUCE THE EFFECTIVE NUMER OF FIBERS IN SOME AREAS OF A HELMET UNDER FABRICATION AND THEREBY IMPAIR THE STRENGTH PROPERTIES OF THE HELMET. CURRENTLY, VERIFICATION OF THE INTEGRITY OF THE HELMET IS BY BALLISTIC TESTING ON A SAMPLING BASIS. THIS PROJECT SEEKS TO DEVELOP A HAND HELD INSTRUMENT CAPABLE OF NONDESTRUCTIVELY (NDE) COUNTING THE NUMBER OF LAYERS OF KEVLAR AT ANY LOCATION IN THE HELMET. THE OBJECTIVE OF THE PHASE I EFFORT IS TO DEMONSTRATE EXPERIMENTALLY THAT A THROUGHTRANSMISSION GAMMA RADIOMETRY INSTRUMENT USING A LOW ENERGY EMITTER WOULD COUNT LAYERS WITH SUFFICIENT ACCURACY TO DETECT MISSION LAYERS. AVAILABILITY OF SUCH AN INSTRUMENT WOULD FACILITATE 100% NONDESTRUCTIVE EVALUATION OF HELMETS. THIS PHASE WOULD INCLUDE DESIGN, CONSTRUCTION, TESTING, AND FIELD EVALUATION OF LABORATORY INSTRUMENTS TO SERVE AS A BASIS IN DEVELOPMENT OF A FIELD GRADE INSTRUMENT FOR USE BY ACCEPTANCE AND MANUFACTURING PERSONNEL.