Bonding composites: aerospace, automotive and railway construction

The aeronautics industry has been a pioneer in the use of high-performance composites (based on carbon, Kevlar and glass fibers), often assembled by bonding, for several decades. This assembly method has in fact been used and developed for its efficiency, the strength of the joints and the lighter weight of the structures it provides. As a result, the aeronautics sector has been the source of numerous innovations, whether in the formulation of new adhesives, the development of application processes, bonded assembly testing methods or construction materials (honeycombs).

The use of composite materials in aircraft construction began around 1970. Since then, the proportion of composite parts has grown rapidly in number and importance, first on military aircraft, then on civil aircraft from the early 1980s.

The aeronautics sector remains an innovator in this field, and should be seen as a source of technology transfer to other industrial sectors, notably automotive, shipbuilding, armaments and mechanical engineering.

In the automotive sector, too, the number of composite parts has risen sharply since 1980.

One of the very first mass uses of composite parts in the automotive industry in Europe was the Renault Espace in 1984, in which all the body panels were made of composite materials — glass-fiber-reinforced polyester, — either compression-molded or injected — which were bonded or bolted with inserts to a metal skeleton body.

The old metal bumpers were replaced from 1972 onwards by SMC (Sheet Moulding Compound) bumpers, as on the Renault R 5, and these composite bumpers and bumpers then evolved into two-part composite parts with reinforcements assembled by gluing.

The use of plastic and composite parts necessitates assembly either by gluing, or by using metal inserts embedded in the resin, which can then be connected by screws and bolts.

The use of plastics and composites is also increasing in the rail transport sector, mainly in the metro, which implies the use of composite bonding in these sectors too.