LIFE EXTENSION OF AN F/A-18 AILERON HINGE USING STRUCTURAL OPTIMISATION AND BONDED COMPOSITE REINFORCEMENT

摘要

F/A-18 inboard aileron hinges suffer from a fatigue cracking problem for which the only current solution is replacement of the component. This paper develops an approach which can be used to reinforce hinges that have not yet developed cracks as well as a method for restoring cracked hinges to an airworthy condition. The approach followed is to firstly use structural optimisation to reshape the hinge to reduce the stress concentration in the critical area. The rework profile detailed in this paper includes an allowance for the removal of cracks up to a depth of 2 mm. Secondly, a boron/epoxy composite reinforcement can be adhesively bonded over the reworked profile to further reduce the level of stress in the hinge. The curved nature of the reinforcement induces through-thickness (peel stresses) in the adhesive and these non-typical adhesive stresses have been considered in the design process. This approach is able to reduce the stresses at the critical location by 16% and a reinforced hinge has been tested satisfactorily to design ultimate load.