Study on contact patch memory and travelling waves of tyres

In this study, the self-excited vibrations of the caster-wheel system are analysed. A low degree-of-freedom mechanical model is considered, in which the lateral deformation of the tyre is described both in the contact patch and outside it. The simple brush tyre model is implemented in order to obtain analytical results by means of minimum number of relevant parameters. The frequencies of the detected self-excited vibrations are resented against the towing speed. Some intricate shapes of the corresponding tyre deformations are presented based on numerical simulations

Contact patch memory of tyres leading to lateral vibrations of four-wheeled vehicles

It has been shown recently that the shimmy motion of towed wheels can be predicted in a wide range of parameters by means of the so-called memory effect of tyres. This delay effect is related to the existence of a travelling-wave-like motion of the tyre points in contact with the ground relative to the wheel. This study shows that the dynamics within the small-scale contact patch can have an essential effect on the global dynamics of a four-wheeled automobile on a large scale. The stability charts identify narrow parameter regions of increased fuel consumption and tyre noise with the help of the delay models that are effective tools in dynamical problems through multiple scales

Linear Stability of Reversing a Car-trailer Combination

In this paper, we investigate the reverse motion of a car-trailer combination. The single track model of the vehicle is used with quasi-static tire model to design a simple linear feedback controller that can achieve stable reversing motion along a straight path. The linear stability of the closed-loop system is analyzed by constructing stability charts in the plane of the control gains. The effect of the reversing speed of the vehicle on the stability is also shown. In order to validate the theoretical results, laboratory experiments are carried out using a small-scale vehicle and a conveyor belt

Stability of towed wheels with elastic steering mechanism and shimmy damper

This paper investigates a low degree-of-freedom wheel model, which describes the lateral vibration of towed wheels, called the shimmy. The model takes into account the lateral deformation of the tyre and also the torsional elasticity and the damping of the steering mechanism. The lateral deformation of the wheel is modeled by the stretched string-like tyre model, which considers the relaxation of the tyre during rolling. The linear stability analysis of this shimmy model is presented and the stability properties are examined in different parameter ranges of the model