Simulation Analysis And Experimental Study On Operation Process Of Self-excited Vibration Subsoiler Based On DEM-MBD Coupling

Self-excited vibration subsoiler is a new subsoiler,which uses spring as accumulator and stores and releases elastic potential energy to adapt to the change of tillage resistance.It is excellent in overload protection and energy consumption reduction.The research and development of this machine mainly adopts the test method,which is limited by time and space,and requires a lot of manpower and material resources.In addition,it is difficult to obtain physical information of soil particle level during the experiment.In order to deeply study the drag reduction mechanism and operation effect evaluation of self-excited vibration subsoiler,a wet particle contact mechanics model and a coupled simulation model based on discrete element method and multi-rigid body dynamics are proposed in this paper.In this paper,the detailed calculation formula of wet particle contact model is given,and the feasibility and effectiveness of the model are verified by the simulation comparison of subsoiler test.At the same time,the detailed calculation process and calculation method of the multirigid system dynamics solver are given,and two typical dynamic models are simulated by using the designed multi-rigid body dynamics module and discrete element module.The simulation results are in good agreement with the theoretical results,which shows the feasibility and effectiveness of the coupling algorithm.On this basis,the simulation analysis of the operating system model of the interaction between the self-excited vibration subsoiler and the soil is carried out,which is helpful for us to have a better understanding of the dynamic characteristics of the self-excited vibration subsoiler and its scarification mechanism.At the same time,the research in this paper also provides a reference for the design and optimization of self-excited vibration subsoiler.The main work and conclusions of this paper are as follows.(1)The physical and mechanical properties of soil(texture,density,moisture content,internal friction coefficient,shear strength,compactness,etc.)and the interaction properties between soil and other materials(static friction coefficient and rolling friction coefficient between particles and steel)were measured and analyzed.(2)A wet particle contact mechanics model is proposed,which defines the adhesion force between particles,increases the maximum adhesion distance and adhesion stiffness coefficient for calculating the maximum adhesion force,and sets the action range of adhesion force.When the distance between particles exceeds the action range of adhesion force,the adhesion force fails,and when the distance between particles returns to the action range of adhesion force,the adhesion force then acts,but the stiffness coefficient of the second adhesion will decrease.The change of adhesion stiffness coefficient can be used to simulate the adhesion between particles.For the wet granular soil model proposed in this paper,the feasibility of the application of the model is proved by comparing the results of the experiment and simulation of subsoiling with the subsoiling shovel,and the reasonable range of model parameters is determined by PB test.The wet particle model provides a new method for better simulating the shear breaking behavior of soil during subsoiling.(3)The solver of multi-rigid body dynamics is established.The calculation flow of multi-rigid-body dynamics solver is given in detail,and the position constraint equations,velocity constraint equations,acceleration constraint equations and Jacobian matrix required for calculation are derived.At the same time,the system dynamics equations with Lagrange multiplier and the solution equations of constraint reaction force and reaction moment are given.For solving the forward dynamics problem,this paper quotes the generalized coordinate block algorithm,and uses the fourth-order Runge-Kutta method to solve the ordinary differential equations formed after block,and then solves the constraint reaction force and reaction moment of the system.In addition,we also discuss the solution of the inverse dynamics problem.(4)Design and develop discrete element method and planar multi-rigid body dynamics coupling algorithm.The analytical discrete element method and the plane multi-rigid body dynamics solver calculate the required parameters respectively,calculate the force through the contact between the particles and the rigid body boundary,and assemble the results into the two solvers for calculation respectively,and update the particle population and the multi-rigid body system.Position information and kinematic parameter information.The reliability and accuracy of the coupled model are verified by comparing the coupled results of translation and oscillation of the particle box single-degree-of-freedom vibration system with the analytical results.(5)The research analyzes the working process of the 1s-300 self-excited vibration subsoiler working unit by using the soil tank test.The range analysis,factor index influence curve analysis and variance analysis are carried out on the orthogonal experimental results of traction force and disturbance area.The primary and secondary factors affecting the traction force and the optimal combination are determined.The spring stiffness,the position of the wing shovel and the operating speed all have significant effects on the traction force;the primary and secondary factors affecting the disturbance area and the optimal combination are determined.The disturbance area has a significant effect,but the spring stiffness stiffness is not significant.(6)In this paper,the coupled simulation algorithm is used to simulate the dynamic behavior of the 1s-300 self-excited vibration subsoiler and the soil action system.The range analysis,influence trend and variance analysis prove that the influence of factors in the simulation and the test is consistent.The error range of the 9 sets of traction simulation results relative to the experiment is 2.01%～14.45%,and the error range of the disturbance area relative to the experiment is 4.97%～14.55%.The results further verify the wet particle model proposed in this paper and the solution of the multi-body dynamics problem.reliability of the device and the coupled simulation algorithm.By comparing the simulation and test results,the reliability of the DEM-MBD coupling simulation algorithm developed in this paper in the analysis of the drag reduction mechanism of the self-excited vibration subsoiler is verified,and the soil loosening mechanism and the self-excited vibration depth of the subsoiler are explained at the same time.The drag reduction mechanism of the loose machine provides a new method for the design of this type of machine.