Simulation of vehicle braking behavior on wet asphalt pavement based on tire hydroplaning and frictional energy dissipation

To investigate the influence of wet conditions on vehicle braking behavior,a numerical-analytical method was proposed for the simulation of tire hydroplaning and frictional energy dissipation. First, a finite element model of tire hydroplaning was established using the coupled EulerianLagrangian method,including a pneumatic tire model and a textured asphalt pavement model. Then,the frictional force on the tire-pavement interface at different speeds was calculated by the model. Based on vehicle braking mechanism and frictional energy dissipation,a calculation method for braking distance was proposed based on a three-stage braking process. The proposed method was verified by comparing the calculated hydroplaning speed and braking distance with field test results.Then,vehicle braking distances and wet friction coefficients were calculated under different conditions. The results show that thinner water film,a more complex tread pattern and higher tire inflation pressure all contribute to the vehicle braking performance; moreover, the pavement texture has obvious influence on vehicle braking behavior,especially at a high speed. The proposed method shows great effectiveness in predicting vehicle braking behavior on wet asphalt pavements.

Inspired by Tree Frog:Bionic Design of Tread Pattern and Its Wet Friction Properties

The wet grip of tire has always been the focus because it is related to the personal safety of passengers directly.Many methods were employed to improve the wet grip of tire.Researchers paid more attention on bionics method recent years.In nature,tree frogs have high adhesion ability in wet environment,which is mainly due to their footpads having fine polygon grooves(mainly hexagon grooves).To improve the performance of wet grip of tire,from the perspective of bionics,inspired by the footpad of tree frog,the bionic hexagon tread pattern was designed.The friction test was carried out to compare with the common tread patterns such as serrated,striped and square patterns.The results showed that the bionic hexagon tread pattern generally had high friction coefficient and directional stability of friction.The main reason was that the hexagon tread block was less affected by the friction-induced torque and the groove of bionic hexagon tread pattern had better drainage characteristic.The bionic hexagon tread pattern provides new idea and method for the design of tires with high wet grip.