UK researchers have developed a method of producing jet engine components that are 70 per cent lighter than normal.
The technology, which is an advance on work originally carried out by Rolls-Royce, will allow aircraft to increase their payload capacity and range.
A team from Oxford University has pinpointed the parameters of heat, pressure and timing to make the manufacturing process viable.
The technique will initially be applied to making bladed rings, or ‘blings’, which were designed to reduce the weight in jet turbine compressor fans.
Usually the fan blades are made separately from the ring and attached afterwards. But blings are single components, where the blades and ring are integrated, making them lighter and cutting manufacturing costs and maintenance problems.
However, because of the high rotation speeds and centrifugal forces they are subjected to, the ring needs to be extremely strong.
The blings are made with lightweight fibre reinforcement in the outer part of the ring for strength.
But there are drawbacks to existing fibre reinforcement methods. The ‘foil, fibre, foil’ or FFF technique, where a metal foil and fibre sandwich is compressed is prone to defects, while spray-forming and electronic deposition of titanium alloys on to ‘monotapes’ can be extremely expensive and the components can suffer excess oxidation.
In conjunction with Qinetiq, Rolls-Royce has developed another technique, ‘continuous fibre-reinforced titanium matrix composites’.
Silicon carbide ‘straws’ coated with titanium alloy are packed together in a regular formation.
The gaps between the straws would increase the risk of fatigue and so are eliminated with high-temperature (900 degrees C), high-pressure (40-50 MPa) consolidation methods.
The research at Oxford means that the right parameters can now be predicted and the arrangement of the fibres properly controlled. Experiments were conducted to validate the computer models used to determine the right manufacturing process.
Rolls-Royce may eventually produce the blings for the F-136, the alternative engine for the Joint Strike Fighter developed in conjunction with General Electric.