BONDED BORON-EPOXY COMPOSITE REPAIR AND REINFORCEMENT OF CRACKED ALUMINUM STRUCTURES

In recent years, the technique of reinforcing and repairing cracked al uminium aircraft structures with composite patches has been gaining ac ceptance as an alternative to bolted mechanical repairs, which often i ntroduce undesirable stress concentrations. To ensure a reliable and d urable bond, various parameters such as the quality of surface prepara tion prior to bonding and the design of the composite reinforcement ar e very important. Often the design of the composite patch is greatly i nfluenced by the geometry of the parent structure. This paper describe s the testing of a composite patch repair and reinforcement of a simul ated aluminium structure with a cracked bolt hole and a step change in geometry. It is shown that while the unpatched specimens failed at ab out 10000 cycles, the patched specimens survived more than 200000 cycl es with very little crack growth. (C) 1996 Elsevier Science.