| The low velocity impact response and damage evolution in unreinforced polymer matrices, conventional polymer matrix composites, and self-repairing polymer matrix composites was investigated. The impact response study of unreinforced matrices and conventional laminates was undertaken because the failure initiation energies, threshold energy levels, failure characteristics and damage evolution in both the matrix material (unreinforced resin plaques) and the composite are intrinsic to proper design of a self-repairing composite. The self-repairing concept was investigated due to its attractive potential to alleviate damage problems in polymer matrix composites. Self-repairing composites, which fall under the category of passive smart polymer composites, have the potential to self repair both micro- and macro-damage resulting from impacts as well as non-impact loading. The self-repairing mechanism is achieved through the incorporation of hollow fibers in addition to the normal solid reinforcing fibers. The hollow fibers store the damage-repairing solution or chemicals that are released into the matrix or damaged zone upon fiber failure to repair and/or arrest damage progression.; The room temperature low velocity impact response and damage evolution in DERAKANE 411-350 and 411-C50 vinyl ester unreinforced resin systems was investigated as a function of impact energy level, sample thickness, matrix material and catalyst system. The low velocity impact response of conventional and self-repairing glass reinforced polymer composites was investigated by addressing the fabrication and some of the parameters that influence their response to low velocity impact loading. Specific issues addressed by this study include developing a process to fabricate self-repairing laminates, processing quality; selection of storage material for the repairing solution; release and transportation of repairing solution; the effect of the number, type and spatial distribution of the repairing tubes, specimen thickness, matrix material and impact energy level. Plain weave S-2 glass fabric reinforcement, vinyl ester 411-C50, and EPON-862 epoxy resin systems were considered in the study of conventional and self-repairing laminates. Composite panels were fabricated by using vacuum assisted resin transfer molding (VARTM) process. The response of unreinforced resin plaques, conventional laminates and self-repairing laminates to low-velocity impact loading was investigated using the impact load histories, impact plots and fractography analysis. |
