Investigation on dynamic characteristics of inserts supporting run-flat tyre based on the modified non-linear ground pressure distribution

Tyres are the sole vehicle components in direct contact with the ground, so making an accurate description of their ground pressure distribution is crucial for studying tyres and vehicles mechanical characteristics. The incorporation of an insert body on the rim leads to a significant divergence in the ground pressure distribution of inserts supporting run-flat tyre (ISRFT) under zero-pressure conditions compared to radial tyres. To elucidate the ground pressure distribution law of ISRFT, this study first develops a theoretical model of ISRFT-ground contact and proposes a modified non-linear ground pressure distribution. Subsequently, the verification and estimation of the parameters related to the modified non-linear ground pressure distribution were conducted. The lateral and longitudinal forces of ISRFT under various load and pressure conditions were then examined in conjunction with the brush tyre model. The results demonstrate that the modified non-linear ground pressure distribution exhibits a high degree of fitting accuracy, with a maximum error of 5.27% between theoretical and simulation. The lateral force increases rapidly when the slip angle is less than 3 degrees, and slows down when it exceeds 3 degrees. Furthermore, the slip angle at which the maximum lateral force occurs under zero-pressure conditions is 3-5 degrees greater than that under standard pressure. The longitudinal force exhibits a rapid increase when the slip rate exceeds -0.2, and then plateaus as the slip rate further increases. It is noteworthy that the maximum longitudinal force under zero-pressure conditions is 23.33% lower than that under standard pressure. This research lays a theoretical foundation for the mathematical modelling of ground pressure distribution of ISRFT and provides a reference for analysing tyres and vehicles mechanical characteristics.