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Non-steady state (NSS) tire cornering properties show obvious differences from steady state (SS) tire cornering properties. A two-DOF automobile model with steer angle as an input is established based on the known NSS tire model considering complex carcass deformation. The tire model can certainly be applied to modelling of a multi-DOF automobile system. The frequency responses of lateral acceleration and yaw rate are then derived. An evaluation index, amplitude-frequency characteristic of relative error (AFCRE), is used to analyze the influences of NSS front wheels (FW) and/or rear wheels (RW) on automotive handling. The influences of NSS FW are much greater than those of NSS RW only on automotive handling. The established automobile model can also be applied to other similar studies of vehicle dynamics.

Based on the modeling of tire vertical characteristics and steady state cornering properties, the model of tire nonsteady cornering is established in this paper using the tire modal parameters extracted experimentally. The dynamic deformation of tire footprint and the influence of tire width for self-aligning torque are taken into account. The footprint is segmented and the influence of speed on non-steady characteristics is included. The analytical formulae for calculation of transfer-function of lateral force and self-aligning torque with respect to lateral displacement and yaw angle are derived. The non-steady characteristics of tire under different loads can be calculated. The calculated results are consistent with the experimental results in the literature. This shows that the tire nonsteady model can be established conveniently using experimental modal parameters. The dynamic characteristics of tires under different working conditions can be calculated directly.