M.Sc Thesis

M.Sc StudentFranco Yaron
SubjectSpatial Model for Performance Prediction of Bulldozer Blade
Interaction with Soil
DepartmentDepartment of Agricultural Engineering
Supervisors PROF. Dror Rubinshtain


Tillage using a bulldozer’s blade involves a wide range of factors and soil properties, such as ground layout, soil strength, heap built-up in front of the tool, flow, and cracks in the soil in the course of the work. The Discrete Element Method (DEM) is designed to model granular materials. Soil - and particularly sandy soil — may be described as a granular material. DEM seems promising for modeling the interaction between blade and soil. The model parameters are usually set using trial and error, as there is no robust theory for setting the soil parameters in the model.

This paper focuses on determination of the parameters for a DEM model of soil-blade interaction, to enable proper representation of the soil in the simulation of blade operation. The models and the simulations were performed using a 2D DEM program (PFC2D), to determine the parameters of cohesionless soil. The method involves measuring the particles’ interlocking property based on direct shear test simulation. The maximum error of the method is 22.8%.

Two-dimensional simulations were performed of a bulldozer blade, moving in a medium of 54,000 particles, working at different angles, depths, and speeds, and in different friction media. The prediction results were compared with McKyes’s calculation model; the average difference between the two methods was -7.24% in the draft forces (DEM prediction was higher) and 1.55% in the vertical direction. The failure line was defined according to the differences in particle velocities; the result fit the prediction of the failure line according to McKyes.

The contribution of the paper lies in the use of DEM as a qualitative and quantitative predictive simulation tool. This tool may be applied in the prediction of the overall behavior of a bulldozer.