|M.Sc Student||Frenckel Nickolay|
|Subject||Tire-Soil Interaction Model based on Finite Elements Method|
|Department||Department of Civil and Environmental Engineering||Supervisors||Professor Emeritus Itzhak Shmulevich|
|Dr. Dror Rubinshtain|
|Full Thesis text - in Hebrew|
The methods for predicting wheel-soil performance can be divided into three main groups: empirical, semi-empirical, and analytical. The relevant analytical methods are based on finite element or discrete element methods (FEM or DEM, respectively). The empirical and semi-empirical methods are based on several assumptions and have some limitations; therefore, they may be unsuitable for the prediction of wheel performance on loose soil. The interaction between a tire and loose soil involves large deformations, flow, and cracks in the soil. It appears that the explicit finite element approach using Lagrangian formulation of the tire and Eulerian formulation of the soil may be suitable for modeling those extreme soil conditions.
A three-dimensional Finite Element Model (FEM) for the interaction between an elastic wheel and a plastic soil was created, using the ABAQUS 6.10 program. The soil was modeled with the Drucker-Prager linear model and defined as an Eulerian body. The wheel was modeled with a linear elastic model and defined as a Lagrangian deformable body. The model of the tire was based on the Alliance AGRI-STAR R-1W 650/65R 38 tire. Simulations were performed to simulate commercial tire tests and work environment. In addition, a fully Lagrangian models and CEL (Coupled Euler Lagrange) models were compared, in order to identify the differences between them. Symmetrical and non-symmetrical presentations of the tire were also compared.
A simulation of cone index soil strength was performed, using four different soils, all within the “soft” strength category, with “soil B” representing the experimental soil.
The Euler model indicated good capability of handling soft soil and an acceptable correlation with experimental results. The Lagrange model produced similar results, but was much less stable numerically.
Important parameters for reliable traction prediction, “rolling radius” and “0% slip condition,” were studied. Based upon the tire - soil contact study, physical definitions were suggested.
The main contribution of the research is the introduction of a reliable numerical model for the prediction of the parameters of tire traction on soft soil. The model allows xamination of traction parameters as a function of tire structure. Based on the study of rolling radius and zero slip, a physical definition for its measurement is suggested. The results of the present research can be used as the basis for further research. In particular, study of radial and bias cross tires structure with different inflation pressures and on different soils is recommended.