Conception et fabrication d’une composante d’intérieur d’avion à base de composites thermoplastiques à fibres discontinues

Abstract

Interior components of airplanes are often made from aluminum, as it is a known material that is lightweight. In order to reduce fuel consumption, aircraft manufacturers seek to reduce the weight of these parts. Since these components are generally not structural, a material that can reduce weight at a reasonable price is thermoplastic composite with long discontinuous fibres (LDF) arranged in a random fashion (Randomly Oriented Strands (ROS)). As this material is relatively new, technical knowledge relating to its use is still limited. The objective of this work is to determine the moulding parameters to obtain good quality parts with a discontinuous fibre thermoplastic composite and to manufacture an aircraft interior part demonstrator. A literature review demonstrating the current gaps in the literature concerning the various objectives is presented. The material chosen consists of strands of various lengths of unidirectional carbon fibre prepreg with a poly-ether-imide matrix. The adequate moulding parameters are first determined following macroscopic and microscopic inspection, evaluation of the density and the porosity rate of simplified moulded parts. Moulding with pressure release (debulk) cycles of up to 10.5 MPa at 350 ° C for 15 minutes with strands have been determined to be the most promising. Then, the material properties are estimated, then validated by tensile tests on standardized coupons composed of different shapes, lengths and alignments of strands, making it possible to affirm that strands of 12 mm in length are adequate for complex regions of small radii of curvature while 25 mm strands are appropriate in less complex regions. The importance of drying the material and then using it within 12 hours is noted. An L-shaped part, forming a luggage bar support located under the passenger seats, is chosen as the demonstrator. It is designed according to specific loading cases and manufactured under the conditions and with the material developed previously, using a mould specifically developed for this demonstrator. A tailor-made mechanical test finally makes it possible to compare the numerical analysis used with the manufactured demonstrator. It is shown that the numerical analysis used for the design of the demonstrator underestimates the mechanical properties of the final part which can therefore be further optimized. The use of ROS composites in aircraft interior applications is ultimately debated. The results demonstrate the potential of this material and of compression moulding to fabricate such parts.

Date	24 Sept 2021
Original language	French
Awarding Institution	École de technologie supérieure
Supervisor	Martine Dubé (Supervisor) & Louis Laberge Lebel (Co-supervisor)