Mode Decoupling Vehicle Suspension System Applied to a Race Car

A suspension system, consisting of hydraulic rams and a central unit, enabling decoupling of the four vehicle body modes, namely bounce, roll, pitch and warp, is investigated. Allowing independent tune of each mode, this system enables the engineer to enhance the performance envelope of a vehicle by exploiting the full potential of the vehicle configuration and achieves the optimal compromise between ride and handling qualities. Attempts to partially decouple the body modes have already been in use, e.g. anti-roll bars, while suspension systems that fully decouple the four body modes have appeared in experimental state [

1

]. A main objective of this research project is the definition of the benefits such a system can have when applied to modern track racers by addressing the extremely challenging requirements of suspension design while satisfying motorsport regulations being passive in function. In order to verify the performance gains, a modern Formula 1 race car is modelled as a multibody system. Two variations of the model are investigated, a conventional one featuring a state of the art suspension and one using the proposed mode decoupling system. Both variations feature same tires and take advantage of the ample downforce courtesy of advanced aerodynamics applied in motorsport. They are subjected to identical handling tests and their performance is validated, showing a definite advantage of the mode decoupling system which is able to better exploit the available tire grip, thus enabling higher velocities in critical conditions. Furthermore, proper tuning of the warp mode enables the decoupling suspension system to handle extreme situations such as riding over a kerb (e.g. through a chicane) or passing through track points of uneven ground (e.g. entering or exiting significantly banked curves). The former case is presented here with both vehicles crossing a chicane, simulated as a double lane change manoeuvre, at 290km/h, when the inner front wheel rides over a kerb of 75mm height (sinusoidal road irregularity of 1m length). The investigated system (blue line) presents superior behaviour (low yaw and ride height perturbations) while it should be noted that in case of a kerb 100mm high, the conventionally suspended vehicle model (red line) is unable to complete the test