Universal Method of Bonding Steel Repairs to Aluminum Structures

Aircraft structural components requiring repair, such as in the C-130, generally bear multi-axial, complex loads and have limited available vicinal space in which to repair the damage and buttress the structure. Restricted space and component geometry limit repair member thickness and the area available to transfer the load into the repair member. Therefore, the objective of the proposed work is to develop and validate a method to bond high modulus repairs onto aluminum frames. TRI/Austin’s basic concept consists of a toughened, high modulus adhesive bonding a high-modulus, high strength steel shim that has been shaped in the depot to fit the specific geometry of the structure to be repaired. When uncured, the adhesive can be applied by brushing or troweling and will conform to any surface geometry. The metal shim is flexible and will conform to curved or cornered, as well as flat, surface profiles. Technical issues that need to be addressed in order for this approach to work include: (1) corrosion of the repair member or aluminum substrate, (2) moisture penetration into the bond line, and (3) to ensure high reliability and sustain compression and shear stresses, the adhesive needs to be toughened.