The effectiveness of boron/epoxy repairs in retarding or arresting cracks in skin grade aluminum have been investigated [1-3]. The durability or long-term performance of bonded composite repairs on damaged structures is still an issue that poses a great a great technical challenge. This is mainly due to the delamination of the composite doubler and/or the deterioration of the interfacial strength of these repairs. Delamination of composite materials, in spite of current technological advancedment in their processing echniques, represents a considerable problem. This is caused by the lack of close contact between the plies due to defects such as voids or spots of excess resin formed during curing of the composite. Fortunately, most repair patches are thin section composites and most of the above mentioned defects induced during fabrication may not be severe. This coulped with proper fabrication encourage the utilization of composite repairs of aircraft structural components. Achievement of an optimum quality adhesive interface and the prevention of its degradation with time are also formidable tasks. This involves, surface preparation and tight quality control [4], means by which their long term performance can be evaluated [5,6], and effective nondestructive methods to assess their long term cumulative damage [7].
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