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Out of autoclave processes development for composite frames manufacturing with high production rate and low cost.

Periodic Reporting for period 2 - COFRARE 2.0 (Out of autoclave processes development for composite frames manufacturing with high production rate and low cost.)

Reporting period: 2017-07-01 to 2018-06-30

The main project bjectives are to carry out process development for composite frames manufacturing with high production rate and low cost.
The main key drivers for achieving this objective are as follows:
1.- To assess of Out of Autoclave processes and Downselection: Liquid Resin Infusion (LRI) and Resin Transfer Moulding (RTM).
2.- Reduction of weight when compared to a traditional metallic frame.
3.- Reduction of manufacturing costs.
4.- To carry out the frame demonstrator manufacturing.
"The main milestone completed in the overall project have been:

a) Selection of the suitable materials for RTM and LI processes such as Hexcel RTM6 for resin and Seartex FC NCF-090416 as fiber.

b) Processes trials completation: quality and geometry tolerances are better achieved in RTM process. LRI cycle time is 50% higher than RTM due to vacuum bag positioning and vacuum leak testing.

c) Life Cost analisys at preliminary level completed: the 2 manufacturing technology (RTM vs LRI) for a defined shape (“C” vs “Z” shape) have been evaluated against a complex and multiple business case scenario provided by the TM. Considering a 4% discount rate and the hypotheses done for the specific purposes it is shows the additional costs in absolute and percentage value of the three expensive alternatives compared to the cost-effective solution, which is the RTM section Type C.

d) Level 1 Lamina Testing: in accordance with the quality results, an higher deviation it was discovered on LRI properties than the RTM one. In general Modulus and Strength of RTM coupons are higher than LRI.

e) Level 2 and Level 3 Test Design completed with a design of 3.8mm meaning 10 plies of NCF.

By the achievent of these results milestone M1 was closed promoting only ""C"" shape with RTM process for next phase.

f) L2 straight ""C"" shape frame produced and controlled with NDI. L3 ""C"" shape curved frame produced and checked.

g) Level 2 tension and compression test to demosntrate the affordability of the process and the validation of the design method including the predicted allowables.

h) Level 3 3-point bending completed in accordance with the predicition for failure mode and load.

By the achievent of these results milestone M2 was closed.

i) full scale demonstrator have been produced, cutted and inspected for Preliminary Production Validation (PPV).

l) cost & weight target have been validated

By the achievent of these results milestone M3 was closed.

Level 1 has been a preliminary phase to confirm the starting TRL and to identify the most critical parameters that affects the process including the way to control them. In the deliverable D1.2 in accordance with the manufacturing trials characterized to assess process parameters for technologies/configuration under trade, the process procedure including the check list have been defined.
The main conclusions of this phase are:
- As agreed with standards defined, the thickness tolerance of the specimens is 2 mm ± 0.08. RTM trials fulfill this requirement.
- Flatness deviation is similar in both processes.
- Seven trials were manufactured by LRI and RTM manufacturing technologies. Low percentage of porosity is present in RTM trial.

With Level 2 and 3, the RTM technology has been promoted to TRL4 – Small Scale of Prototype.
The manufactured specimens (i.e. straight frame and curved frame) prove that the RTM basic technological elements are well known and integrated in a laboratory environment. The level of performance of the frame prototype, (i.e. quality level, structural properties, allowables), is consistent with the requirements of item application.
Within deliverable D6.1 the affordability of the manufacturing process and relative methods to design the aerospace parts, the frame, including a real test case have been validated. Compression, tension and 3 point bending tests have showed key ratio of correlation, close to 100%, and a behavior of the physical test in accordance with the simulation made using material properties selected from phase 1.
By this effort standalone prototype have been implemented and tested at full-scale level using a data sets of realistic cases.
For these reasons it can be concluded that with the TRL4 is validated.

The Full Scale level of the pyramid approach represents the evolution of TRL from 4 to 5, large scale prototype.
At this stage, the fidelity of the process has significantly increasing. The advanced technological elements have been developed to support a full possible application, (i.e. full scale frame, integrated in a fuselage barrel with sub-assy components). TRL5 means that the full scale prototype can be tested in a ‘simulated’ or realistic environment and that the prototyping implementations conform to target environment and interfaces.
For these reasons, full scale demonstrators have been made and cutted and inspected for Preliminary Production Validation (PPV) to demonstrate the compliance with manufacturing expecation.
The technology can be named as Short-term Ready and it is possible within 2-3 years to be close to the aerospace qualification considering moderate investment in R&D. In fact, the analysis made during Cofrare 2.0 project showed that labor cost still impact the convenience of RTM technology for massive production such as frames for aerospace fuselage. From technical point of view, at the same time, the approach carried out in this project for the lamination of the dry NCF fiber is not affordable in an industrial environment because it is time consuming.