Producing the part required Daher to exercise its ability to handle both design and all production processes, from tooling to assembly, for a key part with large dimensions (>10 m) and demanding technical challenges.
In 2018 the equipped spar will be brought into the test cell created for the Corac project.
The design of the spar, a key component of the wing, involves substantial constraints in terms of materials and shape. Dahler reports that the challenge when designing a part of this size lies in producing a progressive airfoil and thickness, which has to be distributed where needed while ensuring the rest is as light as possible, for an optimal weight.
Daher opted for automated processes – from lay-up to inspection, curing and machining – in order to achieve a progressive shape to a degree of accuracy of ±0.15 mm. These processes, which are 80% automated, achieve nominal geometry quality equal to that of machined metal parts, it says. The placement of the unidirectional fibres was automated and the curing was solely done in ovens, without the pressure of an autoclave, in order to improve geometric stability without altering the mechanical properties of the material. This method is also more cost-effective and resource-efficient, lowering the price of the part, the company says.
Another aspect of this optimised approach was the development of industrial tooling while allowing the use of low-cost materials that are reliable over the long term.
Lastly, Daher incorporated a function for reinforcement via co-curing and a function for setting via co-bonding, for easier assembly, optimal weight and a reduced number of attachments.
All these construction and tooling processes are now mature and optimised for mass production. They not only reduce manufacturing costs, but also achieve weight reduction that will improve the performance of future aircraft while reducing fuel consumption, the company states.
“This project has enabled Daher to cement the technological aspects of its strategy, such as the out-of-autoclave material and its positioning as a designer and manufacturer of primary aircraft structures,“ explains Didier Kurtz, Project Manager at Dahler. “The study results and production of the composite spar are a perfect example of the prevailing constructive approach at Daher, which results in innovations and high-performance solutions that can be mass-produced in the short or medium term.”