VITAL was a European project in the EU 6th Framework Programme and stands for EnVIronmenTALly Friendly Aero Engine. The Institute of Structures and Design was involved in areas such as Cold Composite Structure, together with partners such as Volvo Aero, FACC, MS Composites, Rolls-Royce and SICOMP, with the aim of developing a structural outer guide vane using fibre-reinforced composite components. In doing so, a key structural component of the engine was designed that combines both load-bearing and excellent aerodynamic properties.
The load-bearing part of the structure results from the need for an engine mounting, a task that is currently being performed by the intermediate casing located directly behind the compressor housing in the engine architecture. To reduce the overall length of an engine and its structural weight, and for reasons of functional integration, the flow alignment component is integrated directly behind the compressor, making use of what are referred to as Outer Guide Vanes (OGVs).
The aim of the project was to develop a fibre-reinforced composite structure as integrated as possible. However, the interior part of the structure, through which the air in the engine core flows, still needed to be made of metal. In addition to conceptual considerations, the construction of a demonstrator model and conducting appropriate tests was the focus of the work.
The research work at the Institute of Structures and Design focused on thermoplastic structural solutions. The reason for using this approach was the wide range of manufacturing techniques involved with thermoplastic materials – substantially due to the ability to remould and weld the material. These techniques influence the structural design correspondingly.
Attaching the blade structures to the outer and inner rings, and the general application of force induced by the engine mounting quickly became a major problem. The systematic implementation of fibre-reinforced-composite specific design characteristics, such as load transmission at the laminate level and an undisturbed fibre path along load paths led to the design shown in the image – achieved without additional fastenings such as bolts.
For one test planned by the consortium, a thermoplastic vane structure was consolidated and delivered in a hot press. After the appropriate integration into a,test rig the component was successfully tested at Rolls-Royce in Derby in a simulated blade loss scenario that led to large structural deformations.
After completion of the project, the work was optimised for manufacturing 32,000 blades per year as part of the Thermoplastic Composite Structures scheme, in collaboration with the Department of Automation and Quality Assurance in Augsburg, to enable series production with CF-PEEK to be demonstrated.