Bonded boron-epoxy composite repair and reinforcement of cracked aluminium structures

Abstract

In recent years, the technique of reinforcing and repairing cracked aluminium aircraft structures with composite patches has been gaining acceptance as an alternative to bolted mechanical repairs, which often introduce undesirable stress concentrations. To ensure a reliable and durable bond, various parameters such as the quality of surface preparation prior to bonding and the design of the composite reinforcement are very important. Often the design of the composite patch is greatly influenced by the geometry of the parent structure. This paper describes the testing of a composite patch repair and reinforcement of a simulated aluminium structure with a cracked bolt hole and a step change in geometry. It is shown that while the unpatched specimens failed at about 10 000 cycles, the patched specimens survived more than 200 000 cycles with very little crack growth. Copyright © 1996 Elsevier Science.