Titanium F1 Roll Hoop proves concept
Since 2009, 3T RPD have been gaining experience in building structural components for the Formula 1 motorsport sector. Of these types of parts the rear roll hoop structure is one of the largest and most demanding from the point of view of Additive Manufacturing (AM). However, for each of the teams we work with, this safety critical item is also one of the most important and therefore any work that has been carried out has to be kept strictly confidential. This poses the daily problem for 3T of how to demonstrate the kind of work that is possible in AM, whilst also maintaining customer confidentiality.
To come up with a meaningful design for a F1 roll hoop we first had to fully understand all aspects of the use of the roll hoop. The primary function is to protect the driver’s head in the cockpit but other key roles are to act as a critical air intake for the car, and as camera mounts and pick up points for the car itself.
The roll hoop is one of the highest points of an F1 car and a traditionally built roll hoop is a heavy component to have at a high point. A target weight for the roll hoop was set at 1kilo – a potential weight saving of one to two kilos. Since every F1 car must be at least a certain minimum weight, it is common practice to use ballast to balance the car and to meet this minimum thus reducing the weight of the roll hoop means it is possible to put the equivalent, saved weight lower down in the car which helps to improve the car’s performance.
To demonstrate 3T’s success at building structural components like the roll hoop, we worked with Within Technologies to create a completely new design. We wanted to create a generic, lightweight and aerodynamic roll hoop structure that in concept could be fitted to any F1 car and that is designed specifically to be produced by the metal AM process.
A further objective for the team was to ensure that the roll hoop could be designed as a part that, in principal, could satisfy all the FIA safety criteria, including the 120kN front push test.
Our solution was to design and build a “concept roll hoop” to demonstrate our experience, share our learnings and promote greater understanding of the potential of AM.
3T approached Autodesk Within since they offered a new approach to design which freed up the designers from constraints imposed by traditional manufacturing technologies. Their Within Enhance software, with its unique optimisation process coupled to an internal FEA package, was used to create an original lightweight design, incorporating thin walls and internal features, without compromising its structural performance.
Furthermore, a key feature of the software was that it optimised the geometry of the design to minimise the amount of support structures that are commonly associated with the metal AM process.
The Within Technologies approach enabled 3T to produce a part much quicker than could have been made via traditional manufacturing techniques. In fact, the resulting design contains internal features that would be exceedingly difficult and costly if built using any other manufacturing method. The part has maintained its aerodynamic line and features an area to allow for the addition of a camera mount or other component. By selecting the Ti6Al4V titanium alloy, 3T has ensured the part would be lightweight whilst having maximum strength and thus the greatest potential for performance enhancements.
The very nature of the metal AM process requires a support structure to be used during the build of any downward facing surfaces, since the powder bed alone is not sufficient to hold the liquid phase created when the laser has melted the powder. 3T’s roll hoop was produced vertically, to demonstrate the capabilities of building tall components (the part stands 22.5 cm high). Only one small region under the front face of the hoop required support structures to be added for the build phase, whilst the rest of the roll hoop design was self-supporting, thereby minimising the need for support structures. This resulted in faster build times, less waste material, and less post-process finishing operations.
The roll hoop has received positive feedback from the F1 sector, helping to further the understanding of the capabilities of additive manufacturing and increase confidence in the performance of the materials produced by this technology. Furthermore, with additional iterations of the design software, and the respective FEA, it would be possible to model its performance under FIA test criteria.