Improving car performance by multibody analysis

Objectives
The objectives for all the divisions that carried on the development were the weight reduction and the cooling of engine and brakes, together with an overall optimization of components.
As vehicle dynamics division the main changes we studied were the possibility to use tires with a lower diameter to reduce the unsprung mass and to reduce the overall polar moment of inertia, and the modification of the suspension system to work properly with a lowered tire.

Tire Analysis

The study on tires was focused firstly on analysing the experimental data from different tires, paying attention on the lateral and longitudinal force in pure slip and combined slip conditions, the self-aligning torque and the transient behaviour of the tire.

Tire Modelling

Obviously, the processing of data alone is not enough to understand how a different tire can affect the behaviour of the vehicle; at this point the creation of a proper tire model become crucial.

We used the Tire Fitting Tool to generate some Pacejka’s 2002 models with data at our disposal, one for each tire we wanted to investigate for further analysis; to do so, we created specific .tdx files for each test condition, and we compared the model to the experimental data for validations; the sensitivity to pressure and the tire vertical stiffness were also included into the models.

Multibody Analysis

Together with the creation of the tire model, a multibody of the vehicle has been generated, and thanks both the tire model and the multibody, we started to launch some steering pad analysis by which we could compare different tires and two different suspension systems, the old one and the new one, to understand how the changes could affect the behaviour of the vehicle.

On-Track Testing

The multibody analysis was also crucial before and during the on track-testing period, because thanks to it we started to choose a basic setup and developed  it into the right way to maximize the cornering performance of the car; testing was also important to validate the model, using telemetry and driver feedback.

Conclusions
The tire model and the multibody analysis were fundamental instruments for the development of the vehicle and allowed us to understand better the setup changes and to find the right way to make the car competitive at its maximum potential.
Thanks to all the hard work by the team, we managed to win the Formula Student UK event in Silverstone during 19-21th July 2019, marking one of the best results of the team during its history.

We thank the MoRe Modena Racing team to allow us to share with all the readers our experience.

MMR Vehicle Dynamics Division