FRPBonding - Bonding Technologies for Fibre Reinforced Plastic
Transportation and storage containers for cryogenic fluids like liquid helium (LHe), liquid oxygen (LOx) and liquid hydrogen (LH2) used in space applications down to 4.2 K (= -269°C) are commonly made of austenitic steels and aluminium alloys. The main focus in future developments is on mass reduction. Composite components have a high potential in this respect, especially when exposed to extreme environmental conditions.
MAGNA STEYR is a manufacturer of stainless steel cryogenic propellant feed lines for Ariane 5. Since 2009 MAGNA STEYR has been working on the next generation of feed lines for cryogenic propellants made of fibre reinforced composites under ESA’s FLPP (Future Launchers Preparatory Programme).
The basic design is a stainless steel liner which supports the filament winding process and acts as a permeation barrier for the media inside. In the filament winding process, the liner is wound with glass fibre and carbon fibre tapes and cured in an autoclave. The inner steel liner is afterwards electrochemically milled to produce a lightweight thin-walled structure.
Feed lines are exposed to high thermal stresses during operation, e.g. when cryogenic propellants are pumped through during the start sequence. The different thermal expansion and contraction behaviour of steel and composite material may cause the liner to separate from the composite structure.
To identify the best adhesive to avoid disbonding between metal and fibre reinforced plastic required the following tasks to be dealt with:
- Definition of the requirements
- Material pre-selection
- Development of mechanical/chemical pre-treatment processes for pre-selected adhesives
- Evaluation of surface cleaning and additional surface activation processes
- Evaluation of the developed process in both 2D and 3D applications
The selected processes will be applied in a variety of space projects.
The partner Aerospace and Advanced Composites contributed its materials expertise for producing test samples and testing at cryogenic temperatures.
MAGNA STEYR Fahrzeugtechnik AG & Co KG - Karl Ebner
Aerospace & Advanced Composites GmbH - Michael Scheerer