2020 Car

The Team Bath Racing Electric 2020 car was designed to maximise the logical potential of a single-motor topology. Significant effort was once again placed on mass reduction, with the car matching the sub-200kg weight of its predecessor, despite the addition of a full CFD-developed aerodynamics package comprising of a front and rear wing, floor, and side aerofoils.

The hybrid chassis topology was retained from TBRe19, with the front carbon fibre monocoque providing a torsional rigid cockpit for the driver, and steel spaceframe at the rear providing good access and cooling to the car’s tractive system. Through the use of ANSYS ACP simulations and physical destructive experimentation, the sandwich layup structures were optimised, locally to reduce mass, and globally to maximise overall stiffness. A revised spaceframe wrapped tightly around compressed rear packaging, made possible by the relocation of the radiator and brake, and a switch to an Emsiso H300 inverter. Aligned terminals allowed custom ‘flexible’ busbars to bridge the 3 phase current to the Emrax 228 axial flux motor, removing over a meter of HV cabling from the previous design. The two components were water-cooled with an in-house designed additively manufactured octet-truss lattice structure heat exchanger. Through a chain drive reduction ratio and introduction of a rear limited-slip differential, this powertrain could provide over 700Nm of torque to the rear wheels, managed by TBRe’s first in-house developed traction control, tuned using a neural network.

Adjustability was a key focus of the design, particularly within the vehicle dynamics, which featured continuously variable toe angle, caster, scrub radius, ride height and 4-way adjustable air dampers on all corners. A switch to direct actuation simplified and lightweighted the front suspension, and introduced TBRe’s first metal 3D part to a car. The rear suspension was also revised, for a drop to 16” Hoosier tyres and to exploit the space-claim for longer wishbones, and featured an 18-position-adjustable drop link aluminium anti-roll bar. A validated full-car vehicle dynamics model developed in Adams Car enabled sensitivity analysis to be conducted on adjustments, and representative load cases to be generated for mass saving design work, headed by the ubiquitous introduction of carbon rods with bonded aluminium inserts. A new concept of in-house designed custom-cut floating brake disc improved shear force transmission to the spindle, which together with a more aggressive pad compound, custom-manufactured aluminium hose fittings, and a new pedal box, improved both braking performance and safety.

The car’s electrical systems refined the functionality of previous, with a focus on reliability and robustness, and increased resistance against liquid ingress. Optimised ECU software, and a revised set of 12 PCB’s ensured effective control of all electrical systems, with built-in fault monitoring and a full suite of vehicle dynamics sensors introduced. Parameters such a 3-axis accelerations and wheel displacements could be logged for analysis, with a digital screen instantly displaying the car’s speed, temperatures, and power consumption to the driver. 3D harness modelling integrated custom 3D printed sealed backshells, and facilitated its accurate manufacture off-car, and robust clipped paths to be routed. The car was powered by TBRe’s in-house developed battery accumulator, featuring the latest cylindrical cell technology, with integral fans and ducted air channelled by the car’s aerodynamics cooling the 6 sub-packs.

2020 was internally significant to the team also, introducing internal processes, written standards, and improved documentation. A new approach to CAD structuring, an upgrade-based vehicle build plan, and full-detail modelling compressed the build timeline and was paired with exploiting the capability of PLM software to properly manage multi-revision part releases and the vehicle BOM. Investigations into advanced control and artificial intelligence continued, and manufacturing innovations such as curing Onyx 3D prints into carbon lay-ups were made. A TBRe19-retrofit fuzzy logic controlled rear-wheel-steering system was also designed and manufactured for proof-of-concept testing, and an electrochemical battery model was developed to improve the accuracy of cell temperature prediction for accumulator optimisation.

Silverstone (UK), Italy and Australia…TBRe’s first 3-race calendar (and first Australasia event)…but it wasn’t to be! With many of the 5,500 components already ordered/manufactured, and the build on-track to be completed in late April for 150km of on-track testing, Covid-19 struck…TBRe20’s design was carried over to form the basis of TBRe21.

2020 Team:

Mechanical

Electrical and Electronics

Artificial Intelligence