Bonded joints with through-thickness adhesive stresses - reinforcing the F/A-18 Y470.5 bulkhead

A bonded composite reinforcement is being developed for the Royal Australia n Air Force F/A-18 Y470.5 bulkhead crotch region. Due to the curvature of t he surface in this area any bonded reinforcement was predicted to have high through-thickness stresses present in the adhesive under load. A represent ative specimen, the "curved beam specimen" (CBS) was designed using finite element analysis to identify the stress state in the joint and determine th e through-thickness stresses in the adhesive. The specimen was then mechani cally tested to failure under static loads and also under spectrum fatigue loading to determine the viability of the repair. The data from the above p rogram was used to determine an estimate for the through-thickness stress d esign allowable for the structural film adhesive Cytec FM73. It is suggeste d that the CBS will prove to be a suitable specimen for providing generic d ata on the through-thickness static and fatigue strength of adhesives. (C) 1999 Aeronautical and Maritime Research Laboratory. Published by Elsevier S cience Ltd. All rights reserved.