Stress Analysis of Tractor Tire Interaction whit Soft Soil using Non-linear 2D Finite Element Method



Abstract: Compaction under tractors tires is of special concern because the weight of these machines has increased dramatically in the last years. These machines and others associated with crop cultural practices weight enough to significantly compact the soil, especially if the soil is soft with high moisture content during tilling, planting, or harvesting. The stress distribution and the size and form of the tire-soil interface are decisive for the stress propagation in the soil profile. The finite element method is a very useful numerical tool in evaluating different effects of tire on the soil. The goals of this study are to model the response of a soft soil, in relation to tire pressure and axle load. To validate the model by comparison with measured responses in the literature for such a soil and develop the 2D symmetric multi-laminated model of a tractor tire interaction with soft soil and to verify the result with measured field response data reported in the literature. In this study we use a (2D) axisymmetric tire model for the numerical simulation of soil-tire interaction under different load and inflation pressure. The Maximum soil-tire pressure for 70 kpa inflation pressure and 15kN axel load was 83.7 kpa which were approximately 30% less than the stress at the tire contact patch in the field test as cited in the literature. Although in previous investigations with a 3D analysis the difference was 36%. Maximum vertical stress at contact area with 150kPa inflation pressure and 15 kN axel load was 98.6 kPa that was not significantly different than was 101 kPa reported with 3D analysis. In general, more accuracy in 2D compared than whit 3D analysis was obtained due to more accurate meshing in 2D analysis. This investigation shows that maximum stresses in tire occurred at the side wall. Results showed that a simple 2D axisymmetric model can show soil-tire stresses whit good accuracy.