Dynamic modeling and analysis of a formula student car with focus on the friction behavior of the vehicle suspension subsystem

Abstract

Friction is a complex phenomenon that appears as a tangential resistive force acting between contacting surfaces, which have relative motion. Friction has a nefarious effect on the dynamic performance of a large variety of mechanical systems, namely in terms of energy dissipation, noise produced, reliability, etc. Therefore, it is important to develop approaches that allow a detailed identification and prediction of friction influence on the dynamic behavior of multibody systems. Thus, the main scope of this work is to study the influence of friction force on the performance of a vehicle’s suspension system. For this purpose, a multibody model of the University of Minho Formula Student (FSUM) car is utilized as an example of application. The requirements of the suspension systems are greatly dependent on the practical application, where two main categories can be distinguished, namely passenger vehicles and competition vehicles. For passenger vehicles, the design process focuses on gathering simulation data to create control algorithms for active suspension systems [1] and to define Noise, Vibration and Harshness criteria. Passenger comfort metrics are also defined, which will serve as target values to reduce the transmissibility of unwanted vibrations from the suspension and chassis systems to the vehicle’s body [1]. In turn, as far as the competition vehicles is concerned, the prerequisites are quite different, since the main goal is to extract the maximum handling performance from the car, for which a deep knowledge of the suspension system dynamics is crucial to correctly define the setup of the shock absorbers in the presence of friction phenomena [2]. Several works available in literature describe experimental apparatus [3, 4] where the main sources of friction in shock absorbers are identified and studied in an isolated form. The experimental data collected is then compared with computational simulations results [1, 3] in order to develop better dynamic behavior prediction models. The use of multibody dynamics formulations constitutes an alternative and powerful approach to model road vehicles, allowing the simulation of different driving scenarios in which the transient handling response of the vehicle is strongly dependent on the realism of the suspension system’s modeling [5]. The main focus of this work is to develop a multibody model of a formula student car, which allow to examine the dynamic response of the suspension subsystem taking into account the friction phenomenon.