Rolls-Royce is currently in the advanced stages of developing and testing a new UltraFan® aero-engine that delivers a 10% efficiency improvement over the Trent XWB, which is already the world's most efficient large aero engine in service – opening up the possibility of significantly more sustainable air travel compared to existing technology.

As part of the University of Bristol's 15-year partnership with Rolls-Royce, the Bristol Composites Institute has made a significant contribution to UltraFan's Carbon-Titanium (CTi) composite fan system through new advances in the prediction and mitigation of impact damage in composite fan blades and containment casings - an essential requirement for aircraft safety and engine certification.

The Institute has also developed a new cost-saving manufacturing method that is now in use at the Rolls-Royce pre-production facility in Bristol, creating and safeguarding jobs. By hosting Rolls-Royce's University Technology Centre (UTC) in Composites, the University has helped attract continued investment into the local area.

Ensuring fail-safe composites designs

Besides being one of the world's most energy efficient aero engine fan systems, at 3.56m in diameter the CTi composite fan within the UltraFan engine is also the world's largest fan blade ever produced for civil aerospace. This created several significant design challenges. While carbon-fibre reinforced composites have many useful properties for aerospace applications, particularly in terms of reducing weight and fuel consumption, such laminated structures can be susceptible to delamination of the fibre-reinforced layers under impact.

To achieve a commercially viable composite fan system solution, Rolls-Royce's development has drawn on two key research areas facilitated by the ongoing partnership with the University. The first was a new approach to numerical modelling that can predict the occurrence of delamination and ensure that designs mitigate the effects of delamination damage under various impact loads.

The second development was a new Direct Insertion manufacturing method for through-thickness reinforcement (TTR) of the fan blades, achieved by inserting pre-cured carbon fibre rods into the composite laminate. This enables the reinforcement of thick laminates with far higher accuracy and fewer process-induced defects than any other existing means. TTR is essential for managing any potential impact damage. Following the invention of the Direct Insertion method at the University of Bristol, the technology was scaled up at the National Composites Centre, before being implemented by Rolls-Royce at their Composites Technology Facility in Filton.

Growth in composite technologies leads to new facility and jobs

The culmination of these technologies has enabled Rolls-Royce to deliver a technical design solution, that has now been manufactured for the demonstrator engines and run successful ground engine tests. This is a key stage in meeting stringent certification requirements for safe shutdown or run-on, such as the EASA Airworthiness Code CS-E 800.

The University's innovations are saving costs too. The Direct Insertion method alone has achieved a 24 times improvement in rate and cost over the baseline insertion method, saving Rolls-Royce a considerable sum per engine.

The success of these and other composites technologies, is demonstrated through investment by Rolls-Royce in a new Composites Technology Facility at their Filton site. This pre-production factory for fan blades and fan cases represents an investment of £25M and has secured 150 jobs in the Bristol area.

What does the future hold?

Both the University of Bristol and Rolls-Royce are committed to developing innovative solutions to reduce carbon emissions. The partnership between Rolls-Royce and the University of Bristol will enable continuous technological advances to achieve this, and support Rolls-Royce in making lower-carbon flying a reality for airlines and passengers around the world.

Through the University's experience of hosting the Composites UTC, we have built up the necessary experience and capability for innovative technology development at the highest level. Learn more about the collaboration between Rolls-Royce and the University of Bristol from our short video.