Interaction of Four-Screw Vehicle and Soft Terrain Based on SPH-FEM Method

The four-screw propulsion vehicle has high traffic performance and strong maneuverability on the fluidized soft terrain. However, the interaction mechanism between the four-screw vehicle and the soft terrain is quite complicated. The driving performance of the screw vehicle on the soft terrain are not clear, and it is difficult to achieve accurate dynamic control of the four-screw vehicle. The mechanical relationship and motion mode of the four-screw propulsion vehicle-soft terrain interaction are theoretical analyzed, the force characteristics of the screw drive wheel under each motion mode of the vehicle are obtained. The interaction model between soft terrain of tailings dam and four-screw vehicle is established by using smooth particle hydrodynamics (SPH) and finite element method (FEM). Four groups of different screw driving angular velocity and four groups of different screw angular velocity difference are selected to simulate the straight driving and differential steering in soft terrain. The direction and variation trend of the interaction force and its component force of the four screw drive wheels-soft terrain under these two conditions are analyzed, and the relationship between various screw angular velocities and driving performance parameters such as vehicle speed, driving torque, slip rate and sinkage is fitted. The influence of various angular velocity difference of screw drive wheel on steering performance parameters is analyzed, such as steering radius and sinkage. The differences of screw-interaction force and driving performance parameters on both sides of the body during differential steering are compared. The results show that the characteristics of screw – soft terrain interaction force obtained by simulation are identity with theoretical analysis. The speed, sinkage and slip rate of the screw drive wheel are positively correlated with the driving angular velocity. Screw angular velocity difference is inversely proportional to steering radius. The results can provide reference for differential steering control of screw propulsion vehicles.