DEVELOPMENT OF COMPOSITE STRUCTURES WITH ENHANCED DAMAGE TOLERANCE

THE EVOLUTION OF THE AIRCRAFT INDUSTRY HAS BEEN CHARACTERIZED BY A STEADY GROWTH IN THE USE OF LIGHTWEIGHT MATERIALS STRONG ENOUGH TO WITHSTAND THE INCREASING DEMANDS PLACED ON TODAY'S HIGH PERFORMANCE AIRCRAFT. HOWEVER, THESE MATERIALS, SUCH AS GRAPHITE/EPOXY COMPOSITES, SUFFER SERIOUS COMPRESSION STRENGTH REDUCTIONS AS A RESULT OF IMPACT LOADS. FOR THAT REASON, AIRCRAFT DESIGNERS HAVE NOT BEEN ABLE TO USE THE FULL PERFORMANCE POTENTIAL OF COMPOSITEMATERIALS. THIS PROGRAM IS DESIGNED TO ADDRESS THE POSSIBLESOLUTION TO THIS PROBLEM THROUGH THE USE OF ADVANCED WEAVE DESIGNS THAT ALLOW FOR THE INTERLOCKING OF MULTILAYER FABRICS. THIS INTERLOCKING WILL REPRESENT A BALANCE BETWEEN OPTIMIZING THE IN-PLANE LOAD CARRYING CAPABILITY OF THE LAMINATE AND THE ABILITY TO WITHSTAND OUT-OF-THE-PLANE TENSILE LOADS INDUCED BY IMPACT. TWO LAMINAR INTERLOCK PANELS WILL BE WOVEN AND TESTED ALONG SIDE A STATE-OF-THE-ART LAMINATE. BY COMPARING TENSILE STRENGTHS, COMPRESSION STRENGTHS BOTH BEFORE AND AFTER IMPACT AS WELL AS COMPARING DAMAGE AREAS, IT WILL BE POSSIBLE TO ASSESS THE VALUE OF LAMINAR INTERLOCKING AS WELL AS TO ESTABLISH A BASELINE FOR DESIGNING THE MOST EFFICIENT LAMINAR INTERLOCK WEAVE.