Topology optimisation of an automotive disc brake rotor to improve thermal performance and minimise weight

Weight reduction has become a major topic in the automotive industry due to the environmental impacts of carbon emissions. When considering the thermal performance of disc brake rotors, it is increasingly important to optimise their design in a weight-efficient manner. With the advent of electric vehicles, which are heavy due to battery requirements, there is even more impetus to reduce total vehicle mass which can extend driving range. Furthermore, the brake disc constitutes part of the vehicle’s unsprung mass, so minimising brake rotor weight helps to improve ride comfort and reduce damage to the road surface. Considering thermal performance, the temperature rise produced by friction at the sliding interface leads to thermo-elastic deformation within the disc. Consequently, this can change the distribution of contact pressure and cause thermal localisation such as hot-banding and hot-spotting. The phenomenon is called thermo-elastic instability, and if severe, this can cause judder, as well as decrease in fatigue life of the disc. This paper introduces topology optimisation in the development of a ventilated brake disc used on a high performance passenger vehicle with the aim of improving thermal performance, while minimising mass. A baseline ground structure is formulated to enable new conceptual vane geometries for both improved thermal performance and lower disc mass to be derived. This approach allows novel disc designs not previously considered to evolve. Although possibly more difficult to manufacture than the conventional disc, the potential performance benefits of this more radical optimisation strategy are clearly demonstrated. Furthermore, preliminary CFD analysis is utilised to predict the air flow through the conceptual vane designs produced from the topology optimisation process. This allows for estimation of convective heat transfer coefficient for the novel design concepts and enables detailed flow patterns within the vane geometries to be predicted.