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Start of MECATESTERS project (RESCOLL – 18/04/2019)

Rescoll'Blog / 4 juillet 2019

 

RESCOLL was pleased to welcome KVE Composites Group and GKN FOKKER on April 18th and 19th to launch the MECATESTERS project . This 30-months Clean Sky project has for purpose to increase knowledge of thermoplastics welding behaviour. The official presentation below:

"In the aircraft industry, changes in the regulatory landscape, demands for recyclability and demands for reduced emissions have driven research efforts into lighter and more efficient aircraft designs. A key approach to reach these objectives is minimizing weight thereby reducing fuel consumption, leading to a reduction in overall emissions. This requires that traditional materials such as steel, aluminium, and even titanium are replaced with lighter, high-performance materials like composites.

At the same time, the aircraft industry is confronted with a demand for an increased productivity. Production rates for single aisle aircraft need to be increased to 60 to 100 aircraft per month.

High Performance Thermoplastics (HPTP) are an excellent solution to all these issues. These materials offer compelling advantages over metal components: improved working life, lower weight, reduced fuel consumption, and longer service intervals. In comparison to thermoset composites, thermoplastic composites also have several advantages: they can be directly joined using welding techniques, not only making mechanical fasteners unnecessary, but also allowing for lighter designs. Thermoplastic composites are much more damage tolerant, since there is hardly any damage or damage growth in the laminate structure. In addition, their nature also opens up numerous possibilities for rework and repair, and the use of these materials can reduce manufacturing times by as much as 20-30% as compared with metals or thermoset composites. The reduced manufacturing times are mainly contributed to the use of Unidirectional (UD) tapes which allow for a range of automated production methods.

However, to bring these UD tape based thermoplastic materials to a general use in aviation, there is a need to validate thermoplastic welding methods for these materials.

The CleanSky project MECATESTERS (acronym for Micro mEchanical Characterization of A ThErmoplastic Co-conSolidated/welded joinT for usE in aiRcraft fuSelages) project, with GKN Fokker as topic mananger, represents a key step in the progression of such technologies to widespread use in the aerospace sector. Within MECATESTERS, KVE Composites Group and Rescoll cooperate to create a greater level of understanding of the micromechanical behaviour of the welded interfaces for UD tape based laminates, an understanding which is currently limited to carbon fabric based laminates. Issues such as aging, healing, processing parameters, and durability need to be investigated in greater detail in order to develop a coherent approach.

This project will investigate many aspects of thermoplastic joining using the two most promising and mature thermoplastic welding methods in aerospace for carbon fibre reinforced thermoplastics: induction welding and conduction welding. Induction welding is developed by KVE Composites Group for continuous welding of aerospace structures and is used commercially by GKN Fokker for welding of Gulfstream G650 and Dassault 6X rudders and elevators and by Aviacomp for welding fuel tank access panels for the Airbus A220. Conduction welding is developed by GKN Fokker within the TAPAS-2 project for spot welding applications. The main aim is to evaluate and validate these two welding methods for typical fuselage thermoplastic components based on carbon UD LM-PAEK tapes, and to develop a comprehensive understanding of their micro-mechanical behaviour.

In order to reach this goal, four Key Objectives (KO) have been figured out which will make the overall MECATESTERS project realistic and achievable within the proposed 30-month timeframe:

  • KO1: Evaluate the effect of surface conditions upon interface healing.

A detailed examination of different types of surface will provide the Topic Manager with clear guidelines for production, and maintenance with respect to the surface state.

  • KO2: Examine the effects of aging on the durability of carbon UD LM-PAEK parts

The evaluation of aging on the durability of carbon UD LM-PAEK parts will provide valuable information to the Topic Manager in terms of establishing maintenance intervals, engineering tolerances, and lifetimes for carbon UD LM-PAEK parts.

  • KO3: Perform a process window comparison for methods for welding

Two welding method are selected and further investigated in the MECATESTERS project, in order to provide the Topic Manager with an industrially suitable, high-performance, high-quality solution for thermoplastic welding of carbon UD LM-PAEK parts.

  • KO4: Perform mechanical testing to validate the performance of the bonds

The MECATESTERS project will provide the Topic Manager with a detailed analysis of the microstructural behaviour of welded thermoplastic assemblies. This will enable the Topic Manager to select and apply the most optimal joining technology."

From the left to the rigth: Fabien Allegre and Thomas Salat (RESCOLL), Sylvain Chabot and Bas Veldman (G.K.N FOKKER), Maarten Labordus (K.V.E)