The end of 2013 and the beginning of a new design period brought new challenges to the Monash Motorsport team. Constantly striving to keep up to date with the latest manufacturing techniques, learning about the forefront of today’s technology, MMS teamed up with the CSIRO’s Lab 22. Lab 22 specializes in the additive manufacturing of titanium 6Al-4V. Additive manufacturing presents a number of exciting opportunities in part design as it allows organic shapes and structures to be made that regular manufacturing methods would otherwise restrict. The already impressive properties of the titanium are further improved through the electron beam melting process which has many advantages over the more common laser sintering process that is known to leave residual stresses in the part.
After prototyping an initial rear hub design in late 2013 and learning the strengths and weakness of the new technology, the team proceeded to pursue titanium front hubs and uprights. This design was undertaken in an effort to decrease the car’s unsprung mass, a tough challenge as the current designs consisted of already lightweight aluminium.
The titanium hub was designed to be interchangeable with the existing hub with some small changes that we wanted to make after tuning M13. It was also known that certain areas of the printed part would need to be machined to achieve certain accuracies. These included bearings shafts, drilled and tapped holes and mounting faces. Titanium’s superior properties over aluminium, combined with the design flexibility achieved through additive manufacturing, meant that we could incorporate the brake spider into the hub design, however the profile of this spider also needed to be machined for accuracy. The design process for the hub consisted of validation through ANSYS FEA by using a number of load cases at a number of rotations of the hub. After meeting with the post-machining facility it was decided it would be appropriate to incorporate 4-leg ‘spiders’ to each end of the hub design to allow it to be held concentrically whilst machining. These would later be cut out.
The upright design was also designed to be interchangeable. Working within the constraints of the current geometry, the design space was input into Altair Hyperworks and an optimised structure was achieved using its Optistruct topology optimisation feature. This was then interpreted to produce a working design and validated in FEA using multiple load cases.
Many of the surfaces on the part were required to be within small tolerances and there were also many mounting surfaces. The entire manufacturing of the part was therefore closely considered, adding extra material to be machined off just like with the hub. Marand Engineering successfully completed the post-machining operations with no extra support material required.
The finished parts are a testament to the true capabilities of the latest manufacturing technologies. The total combined weight saving was approximately 30%. Monash Motorsport would like to thank CSIRO Lab 22 for their support in this endeavour as well as other associated partners: Marand Engineering, Altair Hyperworks and Leap Australia whom without their ongoing support none of these achievements would have been possible.