Prediction of Soil-Bulldozer Blade Interaction Using Discrete Element Method

Abstract

Modeling the interaction between soil and a tillage implement, such as a bulldozer blade, is a complex task, involving many factors, such as ground layout, soil strength, soil buildup in front of the tool, soil flow, and cracks that may occur in the soil during blade work. The discrete element method (DEM) is a numerical tool designed to model granular materials. Soil, and particularly sandy soil, may be described as a granular material. Therefore, DEM seems to be a promising tool for modeling the interaction between a blade and soil. The model parameters are usually set using a trial-and-error process, as there is no robust theory for determining the soil parameters of the model. This article suggests a method for determining the parameters for the DEM model and simulates the soil-blade interaction of cohesionless soil, as a case study, using a 2D DEM program (PFC2D). The method is based on the interlocking property of the particles. The maximum error of the parameters obtained by the method compared with the actual soil parameters was 22.8%. Selecting the optimum spring constant between the particles may reduce the error. Two-dimensional simulations were performed of a bulldozer blade moving in a particle medium, working at different blade angles and depths, and in different soil parameters. Comparing the simulations with the prediction results using McKyes's calculation model, the DEM model predicted an average draft force 7.2% greater than, and an average vertical force 1.7% less than, the forces predicted by McKyes's approach. The failure line was defined in the simulation according to the differences in particle velocities; the results fit the prediction of the failure line according to McKyes's approach. The contribution of this article lies in the use of DEM as a qualitative and quantitative predictive simulation tool.