CORDIS

Regarding composite materials, the main current focus of the industry is on thermoset based composites, for many reasons, such as:
• Thermoset composites have been used in the aerospace industry since the 1960s, and the design and processing knowledge to exploit the materials has developed substantially.
• Major investments have been made in material property databases for thermoset composite man-rated aerospace applications.
• In many cases, these databases are treated as company proprietary intellectual property, which makes it difficult to justify investment in alternate materials and processes.
• Industries associated with reinforcement that utilizes thermoset-compatible sizing are mature, including weaving and conversion into prepreg.
• Capital equipment and support services, such as tooling and semi-automation methodologies, are well established.
As expected with a maturing technology, major thermoset composite technology innovations and cost reduction opportunities are less frequent, with some notable exceptions.

The use of composite continues to be one of the most important resources to save weight in transportation but it is crucial for society related to the aerospace market and the increase of transport of passenger

The turn of the industry toward thermoplastic composite will help to introduce new outstanding features such as better recyclability, easier part joining while continuing to keep the potential for weight saving. This will help for CO2 reduction and will also be very helpful in the age of more electric vehicles.

The KEELBEMAN project goal is to perform the design and manufacturing of a KEELBEAM section made in thermoplastic composite to validate the technology at TRL3.
The current keel beam structure on short-range aircraft (A320) is made out of metallic material.
Thermoset composite keel beam has been developed for a long-range program like A350 to save weight. But this technology applied to short-range aircraft would be more expansive than the metallic solution and the impact on global mass would be lower than for long-range aircraft.
Therefore, the aim of KEELBEMAN project is to develop a thermoplastic composite concept for a short-range aircraft that could allow for a reduction of the part production cost along with an increase of the production rate. This could be achieved based on two aspects related to thermoplastics specific feature:

• Large scale pieces can be produced using Continuous Compression Moulding (CCM) which is a fast process.

• Parts junction can be realized using the induction welding technique, avoiding rivet assembly which is very time-consuming.

The first activities of the project were dedicated to defining the raw material to be used thus a screening was carried out also taking into account material availability and the project duration.
Due to the geometry of the KEELBEAM component, during the process selection for manufacturing of components, it was decided by CETMA to carry on the development of an innovative Continuous Compression Moulding (CCM) technology which would allow continuous moulding of long components.
Several trials of welding were also defined in regards with material selected and layup part definition, in particular, the mechanical properties relevant for a joining technology were evaluated by a consistent development matrix, both for manufacturing and testing. The induction welding technology patented by CETMA was the core of the welding development.
For the CCM also relevant development plan was set in terms of manufacturing trials, as well as testing.
For short KEELBEAM components compression moulding was selected and evaluated trough out a consistent manufacturing trials plan, as well as testing for mechanical characterization.
In parallel to proper manufacturing development, design activities were carried out first to develop a good number of design concepts based on welded thermoplastic composites and secondly to develop a detailed preliminary design of full Keelbeam structure.
TRL2 review of manufacturing and design approach was assessed together with the Topic Manager.
Further to TRL2 review, a demonstrator of technologies was designed and furtherly manufactured. In the way to manufacture the demonstrator, specific evaluations of manufacturing and inspection were developed and carried out, as well for the final design of Keelbeam activities.
Finally, a TRL3 review was carried out which allowed seeing the level of maturity, including costs estimations and further steps foreseen to TRL6.
In terms of foreseen exploitation of the project results it could be summarized as follows:
• CETMA already positioned in the project Fuselage of Tomorrow for additional activities of welding of thermoplastics, as well as for the use of CCM for long components.
• EURECAT increased the presence in TP composite projects such as COFRARE 2020 and WINFRAME 4.0
• SOFITEC started its internal TP developments for future commercial exploitation
• CTI keep its role of preferred partner for design engineering with Airbus.

It has been achieved a demonstrator of e KEELBEAM made fully in thermoplastic and without any rivet, fully welded by use of CETMA Patent of Induction Welding. this is a big step beyond the state of the art
It has been achieved a new method/process of fabrication of long components named Continuous Compression Moulding developed solely by CETMA
The overall project development leverage the application to meet TRL3

Clearly, the impact of the KEELBEMAN project for society cannot be assessed without having the opinion of AIRBUS and its strategy to introduce the TP composites in future programs. If this is done lighter aircraft can be envisioned, with better recyclability and the TP will be a key enabling technology for the age of more electric aircraft.

From the consortia point of view the impact can be considered as follow:
CETMA has been able to develop a new CCM process that will be studied its patentability
CETMA has used its patented induction welding technology and is now in position for final industrialization, together with an industrial integrator.
CTI become a reference as engineering for the design of Keelbeam in TP as an AIRBUS collaborator
EURECAT increased its knowledge of compression moulding of TP that could now be offered to industrial companies as consultancy.
SOFITEC getting sound introduction in the TP composite world for the future manufacturing challenges with this material, including the NDI by US.