Research On Driving Behavior Of Off-road Tire On Loose Gravel Road Based On Combined Finite Element And Discrete Element Method

Off-road vehicles usually work on soft granular terrain.It is of great significance to investigate the interaction between tires and soft ground,so as to predict the trafficability of off-road vehicles on various complex road and improve the optimization design and performance evaluation of off-road vehicles.Considering that the interaction between tire and soft ground can not be described by the finite element method or the discrete element method effectively,the combined finite element and discrete element method was applied to study the driving behavior of a off-road tire steering on gravel road,in which the off-road tire is described by the finite element method and the gravel road is modeled by the discrete element method.Firstly,the finite element model of the off-road tire is established.The YEOH material model was used to describe the super-elastic characteristics of rubber materials and the orthogonal anisotropic material model was used to describe the anisotropic characteristics of tire rubber-cord composite materials according to the mechanical characteristics of structures of the off-road tire.The simulation analysis of radial and longitudinal stiffness of the tire are carried out.The validity of the finite element model of off-road tire is verified by the corresponding stiffness tests of the tire.Considering that the mesomechanics parameters of the discrete element model cannot be directly obtained through experiments,the triaxial compression test of gravel used for the indoor single wheel soil bin test and the corresponding numerical simulation of triaxial compression test was carried out in order to describe the macroscopic mechanical characteristics of gravel road by the discrete element model.The mesomechanics parameters of the discrete element model used for the simulation analysis of driving behavior of the off-road tire on gravel road were calibrated by making the deviatoric stress-axial strain characteristics of the gravel specimen under the confining pressure conditions of 25 kPa,50kPa and 100 kPa obtained from the simulation coincide with that obtained form the triaxial compression test.Then,the discrete element model of the the gravel road which can describe the macroscopic mechanical characteristics of actual gravel road is established by using Ls-Propost software with gravity compaction calculation.Based on the indoor single wheel soil bin test,a FEM-DEM model of the off-road tire and the gravel road is established.The driving behavior of the off-road tire on gravel road under different slip conditions is simulated by using the combined finite element-discrete element method in LS-DYNA.The pavement rut and travel performance parameters of the off-road tire under different slip conditions,such as the traction force and sinkage,are obtained.The numerical simulation results are basically corresponded with the experimental results,which verified the validity of the established FEM-DEM model and the combined finite element and discrete element method in studying the interaction between the tire and the soft ground.Finally,on the basis of the validity of the combined finite element and discrete element method in studying the driving behavior of the off-road tire on soft ground,the effects of tread pattern,wheel load and tire pressure on traction performance of off-road tire on soft ground are investigated.