Influence of the tire relaxation on the simulation results of the vehicle lateral dynamics in aspect of the vehicle driving safety

Selected experimental research results of truck tire in steady-state side cornering and transient cornering conditions are presented in this paper. Experimental research results of the tire have been used in simulation research of medium duty truck in nonlinear driving conditions. The paper presents the structure of the vehicle dynamics model and a description of applied tire-road interaction model. Simulation research of the vehicle lateral dynamics has been performed in two variants: without and with the model of tire relaxation. During research, the tire relaxation length has been also changed. The steering wheel angle changes were forced as continuous sinusoidal excitation signal with a constant amplitude and with continuously increasing frequency. There have been analysed basic physical quantities characterizing the vehicle lateral dynamics connected with the vehicle active safety, especially including body yaw velocity and lateral acceleration in the centre of the truck body mass. An analysis of research results have been performed in the time and frequency domain. Time courses of analysed physical quantities and their frequency spectrum, obtained for tire-road interaction model without and with the tire relaxation (with different values of relaxation length) have been compared. Based on the simulation research results there have been considered the influence of tire relaxation on the vehicle performance. There have been shown that the tire relaxation can significantly change courses of observed physical quantities connected with vehicle lateral dynamics connected with vehicle driving safety.