The demonstrator features all the typical characteristics of a primary fuselage airframe – thin skin, lightning protection, stringers and frames – to allow a detailed evaluation of these technologies in a true industrial environment.
STELIA has invested several millions in the ARCHES BOX TP Research & Technology project (2015-2017) within the CORAC (French Strategic Advisory Board for Civil Aviation Research) platform. The project is both a technological challenge, thanks to the much lower level of maturity than thermoset matrix composites, and an economic issue, because its global application for the fuselage of single aisle aircraft (with demanding low cost, high rate requirements) must be more cost competitive than the previous generation metallic technologies.
As both the project owner and design authority, STELIA manufactured the demonstrator skin with automated fibre placement (AFP) technology, using thermoplastic (TP) slit carbon tapes and lightning strike protection, with out of autoclave (OOA) consolidation, before completing the final structure assembly at its in-house R&T centre STELIALAB in Méaulte, France.
STELIA selected leading French suppliers in thermoplastic composites to provide complementary technology packages such as dynamic robotic induction welding of TP stringers, fast stamping of stringers and frames and hybrid TP structures by over‐moulding short and long fibre.
For the ARCHES BOX TP project, Porcher’s technical team developed an organosheet from the Pipreg range of thermoplastic solutions as the optimal material for the frames based on the initial STELIA Aerospace specification.
The PEKK-based Pipreg laminates, supplied using a specific carbon reinforcement, were designed to provide a combination of mechanical and fatigue properties from cryogenic to very high temperatures. Thanks to an innovative mixing chemistry and processing, Porcher reports it was able to develop an improved interface between fibres and PEKK.
Pipreg laminates satisfied all testing, engineering and processing targets for the ARCHES BOX TP project and were used by STELIA to produce all composite frames in the demonstrator module, as well as being incorporated into an over-moulded access door component.