Assessment of tire contact spot area on soil surfaces

Abstract

The article presents a comparative analysis of known methods for calculating the contact patch of a pneumatic tire of wheeled vehicles and develops proposals for the conditions of interaction with deformable support surfaces. The classical assessment-calculation of the area of the contact patch of a tire with a support surface is based on a hard concrete surface - a 1 class road. However, in the agricultural and military sectors, soil surfaces dominate, which changes the contact area. A comparative analysis of the known 3 main methods for calculating the area of the contact patch is carried out - national (introduced in 1972) for general-purpose vehicles, European in the agricultural sector and WES - the method of NATO troops.

To take into account the change in the area of the tire contact patch on surfaces that deform with a significant variety of types and physical and mechanical characteristics, it is proposed to use the standard in the WES method - the indicator of soil hardness as a wheel support surface - the cone index CI (cone index), which is used for operational assessment of the patency and mobility of off-road vehicles. In addition to the load on the wheel, a significant role in the formation of the contact patch is played by the change in air pressure in the tire, which is also taken into account on the basis of generalized data on the corresponding change in the radial deformation of the tire.

Clarification of the change in the area of the tire contact patch for specific types and conditions of soils allows for a more correct agroecological assessment of wheeled tractors and vehicles in specific driving conditions.

Keywords: soil compaction, car, tractor, wheel, contact patch, specific pressure, soil hardness.