JEC COMPOSITES MAGAZINE - Issue #58 - June - July 2010 - 42

FEATURE

“Aeronautics”

EB²: a new solution for assembling composites
Because the mechanical behaviour of composite materials doesn’t always allow the use of standard assembly methods, the mass influx of composites in aeronautics brings with it a whole new set of assembly issues, in particular for structural aircraft parts. In response to this limitation, the Capaero Company has developed and patented a new process called EB², for Expanded Bonded Bushing. This innovative process is based on the coldexpansion principle and on microencapsulated adhesive systems. West Coast Industries (WCI), mother company to Capaero’s partner WCIE, has been using cold expansion technology (cold working) for several decades. Besides the attractive mechanical performance linked to the combination of expansion and adhesive-bonding technology, another advantage of the EB² process is that it is very easily implemented.
gradually penetrate the field of aeronautics, more recently in aircraft structural applications to replace metal. Besides their potential for weight savings, these materials also offer very attractive mechanical properties. They have unquestionable advantages. The gradual transition from all-metal to allcomposite aircraft is now under way. The influx of composite materials in the aeronautical field has given rise to new technological problems. Because these materials behave differently than “standard” metals, particularly where damage is concerned, it was necessary to rethink fastener assembly techniques to obtain attractive mechanical properties and reasonably easy implementation. With all this in mind and with the Aquitaine region’s support, Capaero partnered with WCIE (West Coast Industries Europe) and Bordeaux’s LGM²B laboratory for mechanical engineering and materials to develop the idea for the EB² process.

(1) CHRISTOPHE BOIS - MAÎTRE DE CONFÉRENCE - LABORATOIRE DE GÉNIE MÉCANIQUE ET MATÉRIAUX DE BORDEAUX (2) GERMAIN BOULLIER - TOOLING ENGINEER - WEST COAST INDUSTRIES EUROPE (3) ERWANN LE GOFF - DEVELOPMENT ENGINEER - CAPAERO

asteners play a key role in aeronautical structures, because they serve to assemble the different aircraft parts. They are especially numerous on the wings in the form of rivets, screw fasteners, etc. Fasteners allow transferring loads within the structure, so aircraft manufacturers must imperatively have a good grasp of such technology. Fasteners must meet many requirements for things like reliability under load (particularly in flight) or for their mounting process, which is often done manually. Mounting fasteners can also be a challenge from a competitive point of view (e.g. time saving, ease of assembly, the process itself) during production, or later during maintenance. Since as a jumbo jet can contain fasteners in the millions, it is easy to understand how important it is to have an efficient, inventive process that is easy to implement. Over the past few years, we have seen composite materials

Description of the EB² process
The EB² process combines the advantages of the cold expansion process and microencapsulated adhesive systems. Cold expansion (cold working) is a method that has been used for more than forty years to improve the fatigue performance of attachment holes in metal assemblies. A spin-off of this process is the expansion assembly of bushings (used to replace nitrogen assembly), which is WCIE’s BushMax process (see Fig. 1). That is the process used by EB².

jec composites magazine / No58 June-July 2010

JEC COMPOSITES MAGAZINE - Issue #58 - June - July 2010

Table of Contents for the Digital Edition of JEC COMPOSITES MAGAZINE - Issue #58 - June - July 2010