WE PROPOSE TO INVESTIGATE THE EFFECT OF REVERSING THE CURE SHRINKAGE, AND THEREBY REDUCING THE RESIDUAL STRESSES, ON THE DAMAGE ACCUMULATION IN GRAPHITE/EPOXY COMPOSITES.

WE PROPOSE TO INVESTIGATE THE EFFECT OF REVERSING THE CURE SHRINKAGE, AND THEREBY REDUCING THE RESIDUAL STRESSES, ON THE DAMAGE ACCUMULATION IN GRAPHITE/EPOXY COMPOSITES. THE PROPOSED PROGRAM IS BASED ON COMPARISON OF RESIDUAL STRESSES AND DAMAGE ACCUMULATION BEHAVIOR IN EXPERIMENTAL COMPOSITES WITH THAT IS CONTROL COMPOSITES. THE CONTROL COMPOSITE, WHOSE PROPERTIES SERVE AS THE REFERENCE, IS GRAPHITE FIBER COMPOSITE WITH A HEAT-CURABLE EPOXY RESIN MATRIX. THE EXPERIMENTAL COMPOSITE, WHOSE DAMAGE RESISTANCE IS EXPECTED TO BE IMPROVED, IS THE SAME AS THE CONTROL EXCEPT FOR THE ADDITION TO THE MATRIX OF A SMALL AMOUNT OF THERMALLY STABLE POLYMER THAT EXPANDS RATHER THAN SHRINKS ON CURE. THE TECHNICAL OBJECTIVE FOR PHASE I ARE TO FIRST DEMONSTRATE A DIFFERENCE IN COMPOSITE LAMINATE RESIDUAL STRESSES BETWEEN THE EXPERIMENTAL AND CONTROL LAMINATES, AND TO NEXT DEMONSTRATE A RESISTANCE TO DAMAGE ACCUMULATION ON THE PART OF EXPERIMENAL LAMINATES VERSUS THE CONTROL LAMINATES.