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A dissertation submitted to the Faculty of Engineering and the Built Environment, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the degree of Master of Science in Engineering. Johannesburg 2016 / This investigation considers the influence of a three spring and damper suspension system (SDS) on overall vehicle performance. Three SDS systems are used in high performance winged racing cars to manage the effects of the aerodynamic forces. The aim of the investigation was to quantify and compare the performance of a three SDS system to that of a conventional two SDS system. The investigation was carried out on the Bailey Cars LMP2 race car. Physical track testing was conducted on Zwartkops Raceway to measure the vehicle’s performance, with further testing conducted on the vehicle’s tyres. A software model of the vehicle and tyres was then created in ADAMS/Car, with models for the conventional two SDS system, as well as the three SDS system. The ADAMS/Car model was then validated against the test data. A Design of Experiments approach was used to investigate the influence of the parameters in both the suspension models. The optimal set of suspension parameters, that maximised vehicle performance on Zwartkops Raceway, was then identified. The performance of the optimal suspension systems was then compared to quantify the effect of the three SDS system. It was found that the optimised three SDS system travelled 4.38 m less than the optimal two SDS in a 60 second simulation on Zwartkops Raceway. However, the three SDS was effectively able to isolate the pitch and roll stiffness of the vehicle. The optimal three SDS had a greater pitch stiffness and less roll stiffness than the two SDS. This is significant for winged vehicles where aerodynamic forces are highly sensitive to vehicle pitch, such as the Bailey Cars LMP2 race car, allowing for a soft wheel rate without sacrificing the pitch stiffness of the vehicle. / MT2017

Vehicle suspension optimisation is a complex and difficult task, as there are a variety of factors influencing the dynamic performance of a vehicle. During suspension development, the optimisation of a selected few of these factors is often to the detriment of others, as they are all inter-related. In addition, expertise in vehicle setup and suspension tuning is scarce, and is limited to experienced racing teams and large automotive manufacturers with extensive research and development capabilities. The motivation for this research was therefore to provide objective and user-friendly methodologies for vehicle suspension optimisation, in order to support student projects like Formula Student, while having relevance to the needs of the South African automotive industry and racing community. With the onset of digital data acquisition, it has become feasible to take real-time measurements of tyre temperatures, to provide information on how a tyre is performing at a specific point on the track. Measuring the tyre surface temperature can provide a useful indication on whether the tyre is loaded equally or not, and what suspension adjustments should be made to improve tyre load distribution.