Modelling and Simulation of Vehicle Suspension System with Variable Stiffness using Quasi Zero Stiffness Mechanism 2019-01-0452
The dynamics and comfort of a vehicle is closely depended upon the stiffness of its suspension system. Suspension system of a vehicle always had to trade of between comforts and performance of a vehicle, since for comfort softer suspension are preferred which in turn decreases the aerodynamics, cornering performance and increases the ride height of the vehicle whereas in stiffer suspension ride height can be lowered but forces due to bumps is transferred all the way up to the drivers cabin. This paper aims to design a vehicle suspension model with variable stiffness using Quasi-zero stiffness mechanism and study its force displacement characteristics and minimize the fundamental frequencies of the suspension system.
The model developed uses the principle of negative stiffness to achieve low stiffness for the softer suspension system. The mechanism designed comprises of push rod suspension system with three parallel springs attached to one end of the rocker arm, one primary coil spring is mounted perpendicular to the rocker arm and other two secondary springs inclined at an equal angle. In parallel, stiffness of all the three springs are added giving stiffer suspension when required at low ride heights and higher cornering performance. For decreasing the stiffness, an actuator is used to position the secondary springs such that negative stiffness is produced, decreasing the stiffness of the system. The geometry stated above is modelled in CATIA and simulated in MATLAB/Simulink. Graphs of force displacement and frequency-stiffness is studied for both the conditions. Comparative study of conventional suspension and modelled suspension system is done.