Analysis Of Interaction Between Elastic Wheel And Soft Ground Based On Discrete Element Method

With the rapid development of my country’s society and economy,various off-highway vehicles suitable for farmland,beaches,moon,deserts,etc.have become more and more widely used.Studying the interaction between tires and soft ground has important theoretical value and practical significance for improving the passage of vehicles on soft ground.In this paper,the discrete element method is used to study the interaction between the tire and the soil,and the driving wheel of the Dongfanghong tractor LF2204 is used as the research object.The three-dimensional discrete element simulation software Agri DEM independently developed by the research group is used to establish the discrete element between the elastic tire and two different soils.The meta model simulates the rolling process of the elastic tire on the soil,and uses the software performance analysis function to obtain the traction performance of the elastic tire.The simulation results are compared with actual field tests to verify the feasibility and effectiveness of using discrete element method and Agri DEM software to analyze the interaction between elastic tires and soft ground.The main research content and research results of this paper are as follows.(1)In this paper,the physical and mechanical parameters of sandy soil and loam soil are tested.The test content includes the particle size distribution,density,moisture content,accumulation angle,shear strength,friction coefficient and firmness of the soil.Among them,the BT-1600 image analysis system is used to carefully observe and analyze the shape of soil particles,and the shape of the soil is divided into three types: square-like,triangular-like and elliptical-like,which provides a reference for particle modeling;Compile a Python program to identify the accumulation angle of the soil and reduce the error of human measurement;carefully study the shear strength of the two soils under different moisture contents and draw relevant conclusions;test the size,moisture content and compression properties of the straw,Provides an experimental reference for the straw discrete element modeling.(2)Carry out the static pressure test of the tire to obtain the relationship between the radial deformation of the tire and the load under different tire pressures,and then obtain the stiffness coefficient of the tire,which provides a test reference for the selection of parameters when the discrete element simulates the tire.The field traction performance of Dongfanghong LF2204 wheeled tractor was tested,and the hook traction,traction power and driving wheel slip rate of the tractor were tested in different gears,and the test results were compiled into a table.(3)Introduced the characteristics of the three-dimensional discrete element simulation software Agri DEM,and summarized the general steps.First,the elastic tire model is simplified into rigid rims and elastic tires,and the discrete element model of the static pressure test is established using Agri DEM software.Among them,the elastic tire uses particle clusters to be glued into a whole for simulation,and is extracted from the database using the grid method and then bonded to the rim.Then,the stiffness coefficient and damping coefficient of the tire particles are continuously modified to make the discrete element simulation static The simulation results of pressure test are close to the actual test to the greatest extent.(4)The discrete element simulation model of wheel rolling was established using the self-developed software Agri DEM,including the establishment of the geometric model of the soil and the tractor tire,and the selection and establishment of a reasonable mechanical model of the soil and the tire.Among them,the soil geometry is modeled based on the foregoing observation results,and the tire geometry model is modeled with reference to the actual shape and size of the tractor;when a reasonable soil mechanics model is selected and the discrete element is used to simulate sand,considering that there is almost no adhesion between sand and soil,Choose a linear model.When using discrete element method to simulate clayey soil,the clay particle model developed by the research group is used to simulate clayey soil.By comparing the simulated soil accumulation angle with the actual test,the static friction coefficient and rolling friction coefficient of the two soils are calibrated.(5)Simulate the tire rolling process on the soil,and use the performance analysis module in the software to analyze the simulation results.The simulation analysis results are compared with the test results to verify the feasibility of using discrete element method and Agri DEM software to analyze the interaction between elastic tires and soft ground.