The Analysis Of The Interaction Between Wheel And Sotf Ground Based On DEM

Terramechanics is an interdisciplinary of vehicle dynamics and soil mechanics. Itmainly researches vehicle, ground, and the interaction between them. Vehicle dynamics andsoil mechanics have already existed strong research bases, but studying vehicle and groundas a whole system is not widely used. And because of the tire and soil complex mechanicalproperties, as well as their complex exposure, the interaction analysis of tire and softground is the difficulty of the research. With the rapid development of society andeconomic, the more extensive applications of the various non-road vehicles, people demandbetter performance of them. Thus, the interaction between tire and soft ground becomes aresearch hotpot. This paper study the tire of Agricultural machinery, using the group’sself-developed DEM(discrete element method) software to build DEM analysis models ofthe agricultural machinery tire and the soft ground, and simulate the interaction betweenthem. The main research contents and results of this paper are as follows:1. Build the two-dimensional DEM models of the tire and the soft ground. Consideringthe structural mechanics rigid wheel and flexible tire, we use CAD boundary modelingmethod to build rigid wheel analysis model, and use the rim particle and tire particles tobuild flexible tire analysis model. The soft ground analysis model is built by the foundationboundaries and soil particles, in which soil particles can be used three modeling methodsaccording to the different size distribution.2. Analyze the interaction between the wheel and the soft ground using the discreteelement method. According to the rigid wheel and the flexible tire, there are two differentanalysis methods. When the rigid wheel is interacting with soil particles, the total force andthe total torque of the rigid boundary determines the motion and interaction of the rigidwheel. When the flexible tire is interacting with soil particles, there are interactions of tireparticles and soil particles, wheel rim particle. Finally, the total force and torque of thewheel rim particle determines the motion and interaction of the flexible tire. Consideringthe difference of the drive wheels and driven wheels, we analyze the different workingconditions, such as the start, brake and the constant speed.3. Build and select the reasonable mechanical models of the wheel and the soft ground.In the process of the interaction between the wheel and the soft ground, the more importantthing is the selection of the wet soil and the tire particles’ mechanical models. When soilmoisture content reaches22%, we choose wet granular mechanical model. Taking intoaccount of the viscoelasticity of the tire, we establish a suitable improved mechanicalmodel based on wet granular mechanical model.4. Measure the physical and mechanical properties of the wheel and the soil, andestablish the relationship of the macroscopic parameters and microscopic parameters. Inthis article we do the physical and mechanical testing of the soil, and get the microscopicparameters of the soil by simulating the direct shear test and soil compact test based on thediscrete element method. We get the macroscopic parameters of the wheel by summarizingand analyzing large amount of data. It is easy to obtain the microscopic parameters of therigid wheel, when we treat the rigid wheel as a “boundary”. It is also easy to obtain themicroscopic parameters of the rim of the flexible wheel, when we treat the rim of the flexible wheel as a “particle”. Based on the continuous medium model of discrete elementmethod, we establish the relationship between the microscopic parameters and microscopicparameters. Thus, we get the microscopic parameters of the tire.5. Simulate and analyze the interaction of the wheel and the soft ground based on thediscrete element method. The fact that the results of the simulation of the interactionbetween the rigid wheel and the soft ground are in good agreement with previous testresults, verify the feasibility of using the discrete element method to analyze the interactionbetween the wheel and the soft ground. Then by setting different mechanical models andparameters, it can be achieved that simulating and analyzing the dynamic performances ofdifferent working conditions, such as the start, brake and the constant speed. Compared tothe results of simulation with previous experiments and classical theory, it further verify thefeasibility of using the discrete element method to analyze the interaction between thewheel and the soft ground, and lay the foundation of the establishment of digital analysismethod of the interaction between the wheel and the soft ground based on the discreteelement method.