DINAMIT - Development and Innovation for Advanced ManufacturIng of Thermoplastics
Overview
Background & policy context:
Currently, high performance thermoplastic composite parts are mainly used in aeronautical structures. Compared to thermoset resin systems, they have many advantages: impact behaviour, fire resistance, low moisture absorption and welding capabilities. Despite this, thermoplastics are generally restricted to simple geometry parts and limited dimensions as the material and global production costs remain generally high.
Objectives:
The aim of the DINAMIT programme was to foster the widespread use of high-performance thermoplastic (TP) composites on aircraft or helicopter structures. In order to reach that aim, the project focused on the following objectives:
- reduction of prohibitive material costs;
- reduction of the associated forming-consolidation costs;
- development of rapid, flexible, low cost processes for structure assembly;
- reduction of scraps.
The expected main innovations related with the above-mentioned objectives are:
- The development of low cost high performance thermoplastic composite applicable to aeronautical structural components;
- The development of new forming-consolidation processes;
- The development of new welding processes;
- The development of a cost optimisation tool which will assess the developments of innovative TPs materials and processes.
Methodology:
To achieve the general objectives of the programme, the work was divided into six technical Work Packages.
Materials:
After the elaboration of specifications for this new structural TP material, with a polyether ether ketone (PEEK) tape reference, the focus was on the development of a ternary TP blend and its associated prepregs (tape and fabrics). The forming capabilities and mechanical properties of new TP multi-axial fabrics were evaluated. Polyphenylene sulfide (PPS) behaviour in the melt state was analysed for optimising the injection process. Processing routes for PEKK tapes were compared.
Forming processes for Skin:
A new automated lay-up technique associated with vacuum consolidation was developed, and the in situ consolidation (ISC) process was enhanced for double curvature part applications. Benchmarking tests were supplied for comparison of different ISC processes. A specific diaphragm technique was associated with the development of an IR heating model.
Forming processes for Substructure:
A specific TP resin transfer moulding process was developed. A thermoset roll-forming machine was upgraded for TP applications and a continuous forming technique was employed for the manufacturing of contoured profiles.
Welding processes:
Laser technologies were investigated, either for the TP composite assembly, or for surface preparation before welding. An in situ welding technique was developed, to be coupled to the ISC process.
Validation:
A reduced fuselage panel was designed, and sized for validation of the automated lay up technology. Part of a TP fuselage frame was designed for validation of the RTM process. Composite TP wing ribs were manufactured with laser welded roll formed stiffeners. A TP landing gear door was manufactured using in situ consolidation and welding processes.
Cost effective analysis:
Finally, the real impact on cost reduction was evaluated with a specific analytical tool.
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