The history of winter tire development in Japan is described. Studless tires (tires without stud pins) have been developed to replace studded tires whose use has been prohibited due to the dust problem caused by stud pins scraping the road surface. With the spread of studless tires, the icy road surface was polished by the tires and changed to a very slippery and smooth icy road surface. Therefore, the history of development of studless tires is the history of improvement of performance on ice. In order to improve the frictional force of the tire on the icy road surface, it is necessary for the rubber to adhere to the icy surface. For that purpose, adhesive friction, edge effect, and water film removal effect are important as friction mechanisms.
In this review, technologies of materials development and compound development for winter tire are summarized. Especially, implemented materials and compound technologies, which are used for tire, and relating patents are introduced. Some of those technologies about mechanism of improving grip on ice are also discussed.
This paper focused on shape design of winter tyres, including Studless tyre, European Winter tyre and Studded tyre. Tread pattern of winter tyres are designed in consideration of tyre grip on ice and snow surface, which consists of four types of friction forces. This paper shows design methods of tread pattern according to the mechanism of the friction forces. Winter tyres are designed with many conflicts in various conditions on ice and snow road.
In order to develop a tire that can run safely even on snowy and icy road surface, it is necessary to elucidate the complex friction phenomenon with prediction technologies. This paper introduces prediction technologies for winter tire development.
Finite Element Method and Finite Volume Method are used to model tire and snow, respectively. Snow deformation is calculated by the Eulerian formulation to solve the complex interaction between snow and tire tread pattern. In order to represent the shear characteristics of snow, the Mohr-Coulomb plasticity model is used. This prediction technology is used to improve snow traction performance through pattern design. In addition, a crushable foam material and Discrete Element Method are applied to model the mechanism of snow deformation.
Thermal fluid-structure interaction analysis considering phase change using particle-based simulation is applied to elucidate the friction characteristics of rubber on ice. Ice and water are modelled using Lagrangian particle-based method, and a phase change model is introduced to consider ice melting. The method predicts that the coefficient of friction decreases due to low drainage performance when the number of sipes is small.
As for the performance evaluation of winter tires, in general, stable evaluation in the room is desired because the vehicle test is affected by the weather and the evaluation period is limited. In addition, since rubber materials and tire characteristics depend on temperature, temperature is one of the very important factors to obtain high reliable results in tire evaluation, and it can be said that it depends on how it can be tested under constant temperature conditions. We will introduce the general ice performance evaluation technology of winter tires by the indoor vehicle test, indoor drum test method, and lab evaluation technology.