The project aimed to design and manufacture three structural fairings for helicopters using thermoplastic composite materials, namely:
- Upper Panel Rear Fuselage Demonstrator;
- Sponson Fairing Demonstrator;
- Radome Demonstrator.
Materials and processes selection and technology guidelines supported the design phase in which tooling and process parameters will be designed and set-up. The three physical demonstrators were produced and tested according to technical specifications, with a low environmental impact and with a TRL6 Technology Readiness Level. Resistance, induction and ultrasonic welding techniques were studied in depth in the project for the manufacturing of the joinings required for the demonstrators assembling, and their use was preferred to mechanical and bonded joinings, in order to decrease the extensive use of adhesives and mechanical fasteners and to make easier the recyclability at components end-life.
In order to achieve the most economic design and manufacturing technologies, and in order to evaluate the mechanical performances and to achieve the eco-quotation of the demonstrators, a sound methodology was used, together with reliable theoretical, numerical and technological instruments. The performances of the three demonstrators were evaluated through an extensive experimental campaign, starting from tests on coupons at different conditions up to the final tests on the demonstrators. Moreover, the NDI plans for the demonstrators were developed and executed, and the performances will be evaluated also through the eco-quotation of the components. At last all the actions required for the definition of the certification roadmap was investigated and outlined.
The Eco-Fairs project aimed to design and manufacture three structural fairings for helicopters using thermoplastic composite materials and with reduced environmental impact:
- Upper panel Rear Fuselage demonstrator;
- Sponson Fairing Demonstrator;
- Radome Demonstrator.
The three demonstrators were designed and produced according the technical specifications with a TRL6 Technology Readiness Level.
A robust methodology to design and manufacture thermoplastic composite structural components for the aerospace sector was defined in the first WPs, and a number of guidelines were collected. Then the materials and process selection was carried out. The analysis of the thermoplastic composites for the aerospace sector led to the identification of CETEX® (provided by TENCATE), a carbon T300 3K 5HS textile with double sided PPS film. The last important issue that was analysed in WP1 was the manufacturing process selection. The main processes to produce thermoplastic composite components were analysed and described. Among these processes, the compression moulding technique was chosen for the demonstrator manufacturing, because this technique allows a robust control process with good performances and high volume rates. The main guidelines of the compression moulding process were found and described and robust numerical and experimental tools were developed to define optimised process parameters. The final result of WP1 was the definition of a robust methodology for the design of the manufacturing process of thermoplastic composites for the aeronautic sector.
The critical issues regarding the manufacturing of components with complex shape makes clear the importance of the joinings for thermoplastic composites. The definition of robust and high performing joining techniques for advanced thermoplastic composites is the key point for the overcoming of this limit. In the first part of WP2 the joining methodologies for thermoplastic composites were analysed. Thermoplastic welding techniques were studied, because of the possibilities to obtain high performances of the joints, and induction welding revealed to be the most well promising technique. This technique uses the eddy currents generated by an alternating electromagnetic field to heat the material and allows very high performances with a robust control of the process. A new induction welding machine for continuous welding of thermoplastic composites was developed. A big effort in terms of numerical and experimental activities was required for the definition of this machine. The quality of the work performed was confirmed by the high values of the mechanical properties of the manufactured joinings.
In WP3, WP4 and WP5 the three demonstrators of the project were designed and manufactured according the guidelines found in the first part of the project.
In the second part of the project the activities related with evaluation of demonstrators performances were carried out. At first the NDI inspections were carried out according to the NDI plan on the three demonstrators. Then the evaluation of the mechanical performances of the demonstrators was carried out according to the building block approach, starting from testing of material coupon up to the full scale tests on the demonstrators. After the evaluation of mechanical performances the eco-quotation of the demonstrators was carried out, thus demonstrating the lower environmental impact for the thermoplastic components in comparison with the thermoset ones.
Due to the importance of induction welding technique technique for the exploitation of thermoplastic composites for the aerospace sector, in the last part of the project the induction welding process was optimised also for other advanced thermoplastic composites of interest for the aerospace sector, and namely PEEK and PEI composites. The optimised process parameters were found and the experimental activities to find the design allowables for PEEK and PEI carbon composites were carried out.