The aim of this paper is to demonstrate how the principles of co-simulation can be used to calculate the ride response of a vehicle with semi-active suspension. The ultimate goal is to use the approach developed for the estimation of component service loads, enabling optimisation of components based on fatigue life to be implemented. The co-simulation technique employed allows a dynamic vehicle model to be constructed in a Multi Body System (MBS) environment, while two key components, the tyre and active suspension systems, are concurrently simulated in a mathematical simulation environment. The packages used are MSC Visual Nastran MBS software and Mathworks MATLAB/Simulink software. Since previous research [1, 2] has shown that a quarter vehicle model (QVM) is inappropriate for this type of analysis, a lumped parameter full vehicle model (FVM) has been developed in the MBS environment, though for preliminary validation the QVM is used. Using the co-simulation approach, the effects of the semi-active system and the tyre model on the vehicles response to potentially damaging transient inputs (step and potholes for example) are examined. Results show that while the semi-active suspension system employed in this study significantly affects the response of the sprung mass (vehicle body), it has less effect on the unsprung mass (wheel and hub). The converse is true for the tyre model, where the results show different tyre models greatly affect the loads applied to the hub. The paper concludes that the approach adopted is an effective method of integrating the semi-active device, control strategy, and tyre model into the MBS vehicle model. It has significant benefits over alternative methods and has potential for use in the optimisation of suspension components based on fatigue life.
