Adhesive bonding is a method of joining structure together that eliminates some, or all, of the cost and weight of mechanical fasteners. In adhesive bonding, cured composites or metals are adhesively bonded to other cured composites, honeycomb core, foam core, or metallic pieces. Cocuring is a process in which uncured composite plies are cured and bonded simultaneously during the same cure cycle to either core materials or other composite parts. The ability to make large bonded and cocured unitized structure can eliminate a significant portion of the assembly costs.

Adhesive bonding is a widely used industrial joining process in which a polymeric material (the adhesive) is used to join two separate pieces (the adherends or substrates). There are many types of adhesives; some are strong and rigid while others are weak and flexible. Adhesives used for structural bonding are always cured at either room or elevated temperatures and must possess adequate strength to transfer the loads through the joint. There are many types of structural adhesives; however, epoxies, nitrile phenolics, and bismaleimides are the most prevalent. In addition to fabricating large bonded components, adhesive bonding is frequently used for repairing damaged structural parts.

Bonded joints may be preferred if thin composite sections are to be joined where bearing stresses in bolted joints would be unacceptably high, or when the weight penalty for mechanical fasteners is too high. In general, thin structures with well-defined load paths are good candidates for adhesive bonding, while thicker structures with complex load paths are better...