Comparative Study and Optimization of Linear and Non-linear Vehicle Suspension System

Abstract

This thesis presents the comparative study of a quarter car passive suspension model which consists of a two-degree of freedom with a linear and a non-linear suspension component such as: spring, damper and tire. The ride quality including comfort and road holding is the primary factor that is targeted in the study of an effective suspension system. The mathematical model of quarter car suspension is derived, and the dynamic results are evaluated in terms of the sprung and unsprung mass displacement, velocity and acceleration. The simulation is performed for two different types of ground vehicles, light-duty and heavy-duty vehicles. Results show that the addition of the non-linear suspension components in the dynamic model of the two vehicles decreases the vibration of the vehicle. In case of sinusoidal road input the ride comfort performance is improved by 66.4% and road holding performance is improved by 37.2%. In case of unit step road input the ride comfort performance is improved by 26.86% and road holding performance is improved by 13.8%. By optimizing suspension design parameters for linear and non-linear suspension the sprung mass acceleration is decreased by 71% and 90.9% under sinusoidal road input respectively. Similarly it is reduced by 50% and 62.5% under unit step road input respectively.