15:30 Tuesday 22nd October 2019

Formula Student: Methods for Low Volume Composite Manufacturing

Formula Student involves designing, manufacturing and competing with a single race car each year. All of this is done with limited resources - this includes budget, as well as tools, machines and most importantly, knowledge and experience. This requires the student engineers to use the most suitable manufacturing methods for this special scenario. Oxford Brookes Racing, for many years, used a classical method of manufacturing composite materials for structures such as wings. Even for small, and relatively complex elements, an upper skin would be made on one mould, a lower skin on another. Internal ribs and transverse beams would be moulded separately, and the whole structure would then be assembled by hand and bonded with limited jig use - resulting in an aerodynamic component with limited accuracy to that which was tested in CFD. A new manufacturing method is now in use for such elements, where no bonding is required, and element accuracy is governed by the machines used. The method uses a machined, low-density closed-cell foam core, wrapped in adhesive film and pre- impregnated laminate, enclosed in a mould. We have been able to use two types of mould, the first being multiple machined components of traditional tooling board which are then dowelled and bolted together to enclose the component. The second utilises stereolithography rapid prototyping, provided by our technical partner, RPS, to create more complex moulds. This method has multiple benefits, including a continuous thickness across the whole part, meaning heat penetration throughout the part is consistent, avoiding ‘dry’ and ‘wet’ areas and therefore a consistent join between core and laminate. This also allows us to avoid the cost of tooling board and complex machining and frees the resource of the machines for other components. Both methods result in the desired external surface, upper and lower, to be exactly as designed; a continuous leading edge with no seam; lighter and stiffer components which vibrate less. This presentation will demonstrate how Formula Student have used this technology in our Formula Student car and how it may be suitable for other high-performance, low-volume applications.

Joe Jones, Oxford Brookes Racing