Time Response Analysis in Suspension System Design of High Speed Car

摘要

A land speed record vehicle is designed to run on a flat surface like salt lake where the wheels are normallymade from solid metal with a special suspension system. The suspension is designed to provide a stableplatform to keep the wheel treads on tract, to insulate the car and the driver from the surface irregularities and totake part of good handling properties. The surface condition of the lake beds is basically flat without undulationsbut with inconsistent surface textures and ridges.Spring with nonlinear rate is used with the reason that the resistance builds up roughly proportional to theaerodynamic download for keeping the height more nearly constant.The objective of the work is to produce an efficient method for assisting the design of suspension system. At theinitial step, the stiffness and the damping constants are determined based on RMS optimization by following theoptimization strategy i.e. to minimize the absolute acceleration respect to the relative displacement of thesuspension.Power bond graph technique is then used to model the nonlinearity of the components i.e. spring and dashpot ofthe suspension system. This technique also enables to incorporate the interactions of dynamic response of thevehicle's body with aerodynamic flow as a result of the base excitation of the ground to the wheels.The simulation is conducted on the platform of Simulink-MATLAB and the interactions amongst thecomponents within the system are observed in time domain to evaluate the effectiveness of the suspension.