ACG reaches development milestone in out-of-autoclave capability for complex aircraft primary structures

Advanced Composites Group Ltd. (ACG), a member of the Composites Division of Umeco plc, reached an important milestone when it successfully demonstrated the capability of its MTM®44-1 Out-Of-Autoclave (OOA) toughened, structural prepreg resin system on the first sub-scale wing box demonstrator produced for the collaborative research programme 'ALCAS' (Advanced Low Cost Aircraft Structures).

ACG is a major partner in the Business Jet Platform of this Airbus and Dassault Aviation led, 101m€ EU-funded programme aimed at validating the designs and technologies for lower cost aircraft structures.

ACG's main focus in the programme is to design and manufacture the lower cover of a structural wing box demonstrator. This cover would then be used by four other partners (Alenia, Dassault Aviation, SAAB and Stork Fokker AESP) to complete the structure using different materials, designs and manufacturing options.

The four structures would subsequently be tested to validate and compare the embodied technologies.

The cover, composed primarily of MTM44-1/IMS UD prepreg, features 'T' shaped stiffeners co-cured to the underlying skin, which varies in thickness from 5 to 17mm. The structure was successfully cured in a one-shot, oven-vacuum bag cycle. Detailed stringer run out features were substantiated by coupon and sub-element level testing.

ACG's cover was subsequently assembled with the rest of Fokker's structure and the complete structural wing box demonstrator was sent to VZLU (V?zkumn? a zku?ební leteck? ústav, a.s.) in Prague, where static loading, fatigue and impact tests were performed to assess ultimate failure load. The demonstrator failed at 10% over the specified design ultimate load, thereby proving the effectiveness of the materials, designs and technologies involved.

The cover panels destined for the remaining three structural wing box demonstrators have already been manufactured at Advanced Composites Engineering (ACE), ACG's component manufacturing facility, using the same prepregs and OOA cure process.

When compared with other OOA structural systems, ACG's MTM44-1 exhibits the highest mechanical performances and can compete with a wide range of high toughness, autoclave curable epoxy systems.

ACG first introduced OOA materials and technology for aerospace structural applications in the early 1990's and has radically developed its product portfolio for this and many other demanding applications.

Numerous civil and military programs currently use ACG's OOA materials to manufacture structures by hand lay-up and state-of-the-art automated systems, including Automated Tape Lay-Up (ATL) and Automated Fibre Placement (AFP).