A soil subsoiling simulation method based on DEM-FEM two-way coupling

Abstract

The application discloses a soil deep loosening simulation method based on DEM-FEM bidirectional coupling. The method comprises the following steps: establishing a soil discrete element model and a deep loosening tool finite element model; using the discrete element DEM simulation to analyze the influence law of soil characteristic parameters and deep loosening tool motion parameters on soil deep loosening effect and deep loosening tool working resistance; changing the soil characteristic parameters and deep loosening tool motion parameters, and calculating the information such as soil deep loosening particle mixing degree, deep loosening tool working efficiency and working resistance under different variables; analyzing the influence law of the working resistance obtained from the DEM on the deep loosening tool structure through the finite element FEM analysis, changing the soil structure parameters and deep loosening tool structure parameters, and counting the statics and dynamics analysis results under different variables; simulating through the DEM-FEM bidirectional coupling, analyzing the soil deep loosening mechanism of the deep loosening tool, and obtaining the parameter and structure optimization results. Compared with the prior art, the application can effectively reduce resistance and consumption, and improve working efficiency.

Description

Technical Field

[0001] This invention relates to the field of agricultural machinery, and in particular to a soil deep loosening simulation method based on DEM-FEM bidirectional coupling. Background Technology

[0002] Subtillage machines are key equipment in deep soil tillage. Their operation requires adaptability to diverse crops, farmland shapes, soil structures, and surrounding environments. The deep tillage process utilizes the movement and power of the blades to subject deep soil layers to a combination of shearing, bending, compression, and stretching, resulting in loose, fine-textured soil and a smooth surface. The effectiveness of deep tillage is directly related not only to soil characteristic parameters (including soil particle density, particle size, and particle number) and the movement parameters of the subtillage machine (including working speed, tillage depth, and penetration angle), but also to the structural parameters of the subtillage blades (including the number of blades, blade thickness, blade arrangement, and blade installation angle). Finding a method to analyze the mechanism of deep soil tillage is crucial. This method can not only analyze the influence of the movement parameters of the subtillage blades on the soil tillage effect, but also analyze the influence of different parameters on the tillage resistance of the blades, thus obtaining optimal parameters and structure.

[0003] Currently, soil deep tillage research only uses the discrete element method to study soil characteristic parameters and deep tillage cutter motion parameters, or only uses the finite element method to study the influence of deep tillage cutter structural parameters on deep tillage effect and verifies them through field trials. Although the above methods are reliable, they do not form a two-way feedback closed loop and the experimental results are not fed back in time. During the experiment, due to the limited resources of the experimental field and the fact that the soil characteristic parameters have changed after the deep tillage experiment, the experimental field is not reusable in a short period of time, and the effect of the improved deep tillage machine often cannot be verified in real time.

[0004] The above content is only used to help understand the technical solution of the present invention and does not represent an admission that the above content is prior art. Summary of the Invention

[0005] The main objective of this invention is to provide a soil deep tillage simulation method based on DEM-FEM bidirectional coupling, which aims to solve the problems of heavy weight, high working resistance, and severe wear of deep tillage machines in multi-characteristic soil environments.

[0006] To achieve the above objectives, this invention provides a soil deep tillage simulation method based on DEM-FEM bidirectional coupling, the method comprising the following steps:

[0007] Step 1: Define the structural parameters of the soil, establish a discrete element model of the soil DEM, define the structural parameters of the deep tillage tool, establish a three-dimensional model of the deep tillage tool, and mesh the three-dimensional model to obtain the finite element model of the deep tillage tool FEM.

[0008] Step 2: Import the deep tillage tool FEM model into the soil DEM discrete element model, define soil characteristic parameters for the soil DEM model, and define motion parameters for the deep tillage tool FEM finite element model;

[0009] Step 3: Based on DEM soil deep loosening simulation, analyze the influence of soil characteristic parameters and deep loosening tool motion parameters on the soil deep loosening effect. Change the soil characteristic parameters and deep loosening tool motion parameters, and repeat steps 2 and 3.

[0010] Step 4: Based on DEM soil deep tillage simulation, analyze the tillage resistance experienced by the deep tillage cutter, analyze the influence of soil characteristic parameters and deep tillage cutter motion parameters on the tillage resistance of the deep tillage cutter, change the soil characteristic parameters and deep tillage cutter motion parameters, and repeat steps 2 and 4.

[0011] Step 5: Use the tillage resistance obtained from DEM as the load boundary condition for FEM finite element analysis, perform static and dynamic analysis, analyze the influence of tillage resistance on the deep tillage cutter structure, change the soil structure parameters and deep tillage cutter structure parameters, and repeat steps 1-5.

[0012] Step 6: Analyze the deep loosening mechanism of soil through DEM-FEM bidirectional coupling simulation to obtain the optimization results of deep loosening tool motion and structural parameters under different soil characteristics and structural parameters.

[0013] The specific steps of step 1 include:

[0014] Soil structure parameters include the number of layers and the space between particles in each layer. Deep tillage tool structure parameters include the number of cutter heads, the thickness of the cutter heads, the arrangement of the cutter heads, and the installation angle of the cutter heads.

[0015] Step 2 includes the following specific steps:

[0016] Soil characteristic parameters include particle density, particle size, and particle number, while the motion parameters of deep tillage tools include working speed, tillage depth, and soil penetration angle.

[0017] Step 3 includes the following specific steps:

[0018] The deep tillage process of deep tillage tools in the soil was simulated, and the soil deep tillage particle mixing degree and tillage efficiency were analyzed and statistically analyzed.

[0019] Using the Analyst module of EDEM post-processing, the number of soil particles in contact with each other in each layer during deep tillage was plotted as a curve, allowing for the calculation of particle mixing degree by obtaining the changes in particle types in each soil layer after deep tillage. The formula for calculating particle mixing degree is:

[0020] In the formula, N eN represents the number of contact points between the two types of particles during deep loosening. b This represents the number of contact points between the two types of particles after deep loosening.

[0021] The number of bonding bonds broken between soil particles during deep tillage was plotted as a curve. Originally compacted soil was broken up and dispersed under the tillage of the deep tillage cutters. Therefore, the soil deep tillage efficiency can be obtained by calculating the slope of the curve in the direction of travel of the deep tillage cutters based on the curve. The formula for calculating tillage efficiency is:

[0022]

[0023] In the formula, S b S represents the number of bonding keys broken at the start of deep loosening in the travel direction by the deep loosening tool. e t represents the number of Bonding bonds broken at the time of deep relaxation completion. b Let t be the start time of deep loosening for the deep loosening tool in the direction of travel. e This marks the completion of Fukamatsu's work.

[0024] Step 4 includes the following specific steps:

[0025] Based on DEM soil deep tillage simulation, the EDEM post-processing Analyst module is used to plot the absolute tillage resistance of the soil as a time curve, which is the resultant load of the deep tillage cutter on the soil in various directions during the deep tillage process. At the same time, the tillage resistance of the deep tillage cutter on the soil in the X, Y, and Z axes after the resultant force is decomposed is plotted as a time curve of the tillage resistance of each axis.

[0026] Step 5 includes the following specific steps:

[0027] The tillage resistance results from step 4 are output in Pressure format. The peak time of the resultant load on the subsoiler is set as the start and end time. The output Pressure data is saved in .axdt format, and the position of the subsoiler at the peak load state is retained. The data includes the node ID number of the mesh element, the spatial coordinates of the node, and the element load. To ensure that the output Pressure load is accurately applied to the subsoiler, the position of the subsoiler at the peak load is observed through the EDEM analysis module. The position of the finite element model in ANSYS Workbench is adjusted to ensure that the coordinate systems of the DEM and FEM models are consistent in the finite element analysis. The adjusted subsoiler is saved as a .stl file as the model for the finite element analysis. The DEM Solutions module in ANSYS Workbench is used to read the output .axdt Pressure load file, and it is associated with and loaded into the Static Structural and Modal modules as the load boundary conditions for the finite element analysis. The Pressure is applied to the structural surface of the subsoiler that contacts the soil when it is subjected to the peak load, and the static and dynamic analysis of the subsoiler is performed.

[0028] Step 6 includes the following specific steps:

[0029] Based on DEM-FEM bidirectional coupled simulation, the deep tillage effect under different soil characteristic parameters and different deep tillage tool motion parameters is statistically compared, the soil deep tillage mechanism is analyzed, and the optimization results of deep tillage tool motion parameters are obtained. The static and dynamic analysis results of deep tillage tool structural parameters under different soil structural parameters are statistically compared, the deep tillage tool structure is optimized, and the optimization results of deep tillage tool structural parameters are obtained.

[0030] This invention establishes a discrete element model (DEM) of the soil and a finite element model of the deep tillage tool. It uses DEM simulation to analyze the influence of soil characteristic parameters and deep tillage tool motion parameters on the deep tillage effect and tillage resistance. By changing the soil characteristic parameters and deep tillage tool motion parameters, it calculates information such as soil particle mixing degree, deep tillage tool tillage efficiency, and tillage resistance under different variables. The invention also uses finite element model (FEM) to analyze the influence of tillage resistance obtained from the DEM on the deep tillage tool structure. By changing the soil structure parameters and deep tillage tool structure parameters, it statistically analyzes the static and dynamic results under different variables. Finally, it uses a two-way coupled DEM-FEM simulation to analyze the soil deep tillage mechanism of the deep tillage tool and obtain parameter and structural optimization results. Compared with existing technologies, this invention can effectively reduce drag and energy consumption, and improve tillage efficiency. Attached Figure Description

[0031] Figure 1This is a flowchart illustrating an embodiment of the soil deep loosening simulation method based on DEM-FEM bidirectional coupling of the present invention.

[0032] Figure 2 This is a schematic diagram of the soil discrete element model according to an embodiment of the present invention;

[0033] Figure 3 This is a schematic diagram of the finite element model of the deep tillage tool according to an embodiment of the present invention;

[0034] Figure 4 for Figure 2 and Figure 3 A schematic diagram showing the deep loosening process completed by the coupled deep loosening tool in the soil. Detailed Implementation

[0035] The present invention will be further illustrated below with reference to the accompanying drawings and specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. After reading this invention, any modifications of the invention in various equivalent forms by those skilled in the art will fall within the scope defined by the appended claims.

[0036] Reference Figure 1 This invention discloses a soil deep loosening simulation method based on DEM-FEM bidirectional coupling, comprising the following steps:

[0037] Step 1: Refer to Figure 2 , Figure 2 This is a schematic diagram of a soil discrete element model according to an embodiment of the present invention. The structural parameters of the soil are defined, and a soil DEM discrete element model is established. The specific steps are as follows:

[0038] Using EDEM software, structural parameters were set based on soil particle type and actual deep tillage tool material parameters, including the number of soil layers and particle space in each layer. The Bulk Material module and Equipment Material module were configured, and parameters such as Poisson's Ratio, Solids Density, Shear Modulus, Coefficient of Restitution, Coefficient of Static Friction, Coefficient of Rolling Friction, ModifyShape, Physical Radius, Contact Radius, Position, and Calculate Properties were refined.

[0039] A particle factory was established using the Geometries module of EDEM software. The initial settings for particle generation space, particle type, particle quantity, and entry velocity for each soil layer were defined. Loose, uncompacted soil particles were simulated using monosphere particles, randomly distributed throughout the soil. Larger clods and stones were simulated using large monosphere particles. Multiple smaller monosphere particles were bonded together and replaced with the Particle Replacement function to simulate a stone breaking effect. Larger particles and clods were randomly distributed throughout the soil layer. The specific operation was as follows:

[0040] First, using the EDEM API function, select PluginFactories in the Geometries module, import the particle model, and select Particle Replacement in the library. In the Physics module, select Interaction, then Particle to Particle, and edit the Contact Chain. In Additional Models, check Bonding and set parameters such as Bonding bond generation start time, NormalStiffness per unit area and Shear Stiffness per unit area, Critical Normal Stress, Critical Shear Stress, and Bonded Disk Radius. In the Physics module, select Interaction, then Particle Body Force, and edit the Contact Chain. In Plug-in Models, check Particle Replacement.

[0041] Next, using the Environment module of the EDEM software, set the Gravity, enter the Simulator Settings pre-calculation interface, and set the time step, total time, and simulator grid.

[0042] Finally, simulated particle generation is performed, and the soil discrete element model is saved as a .dem file in the Analyst post-processing analysis interface.

[0043] Reference Figure 3 , Figure 3 This is a schematic diagram of the finite element model of a deep tillage tool according to an embodiment of the present invention. The structural parameters of the deep tillage tool are defined, a three-dimensional model of the deep tillage tool is established, and the three-dimensional model is meshed to obtain the FEM finite element model of the deep tillage tool. The specific steps are as follows:

[0044] The SOLIDWORKS software was used to create a 3D model, and structural parameters were set, including the number of cutter heads, cutter head thickness, cutter head arrangement, and cutter head installation angle. The 3D model of the deep tillage tool was then exported as a .x_t format.

[0045] In the Mesh module of ANSYS Workbench software, the 3D model of the deep loosening tool is meshed, and the meshed finite element model is exported as a .stl format file.

[0046] Step 2: Import the deep tillage tool FEM model into the soil DEM discrete element model, define soil characteristic parameters for the soil DEM model, and define motion parameters for the deep tillage tool FEM finite element model.

[0047] Import the deep tillage tool finite element model into the saved .dem file, and input the obtained .stl format file. Set the starting position and rotation angle of the finite element model to keep the deep tillage tool finite element model in a suitable initial state. Add motion, simulation start and end time, working speed, tillage depth, and soil penetration angle according to actual conditions to complete the discrete element simulation preprocessing.

[0048] Step 3: Refer to Figure 4 , Figure 4 for Figure 2 and Figure 3 A schematic diagram of deep tillage completed by the coupled deep tillage tool in the soil. Based on DEM soil deep tillage simulation, the influence of soil characteristic parameters and deep tillage tool motion parameters on the soil deep tillage effect is analyzed. By changing the soil characteristic parameters and deep tillage tool motion parameters, the soil particle mixing degree and tillage efficiency under different variables are analyzed and statistically analyzed. The specific steps are as follows:

[0049] A DEM (Digital Elevation Model) soil deep tillage simulation was performed. After the simulation, the Analyst interface was used for post-processing analysis to display the distribution of each particle. A curve was plotted showing the number of soil particles in contact with each other during the deep tillage process. The particle mixing degree was calculated by obtaining the changes in particle types in each soil layer after deep tillage. The formula for calculating the particle mixing degree is:

[0050]

[0051] In the formula, N e N represents the number of contact points between the two types of particles during deep loosening. b This represents the number of contact points between the two types of particles after deep loosening.

[0052] The number of bonding bonds broken between soil particles during deep tillage was plotted as a curve. Originally compacted soil was broken up and dispersed under the tillage of the deep tillage cutters. Therefore, the soil deep tillage efficiency can be obtained by calculating the slope of the curve in the direction of travel of the deep tillage cutters based on the curve. The formula for calculating tillage efficiency is:

[0053]

[0054] In the formula, S b S represents the number of bonding keys broken at the start of deep loosening in the travel direction by the deep loosening tool. e t represents the number of Bonding bonds broken at the time of deep relaxation completion. b Let t be the start time of deep loosening for the deep loosening tool in the direction of travel. e This marks the completion of Fukamatsu's work.

[0055] Soil characteristics vary depending on the season, soil layer, and soil composition. Tillage soil exhibits significant multi-characteristics, including soil particle density, particle size, and particle number. The tillage effect of subsoilers also varies greatly under different motion parameters, such as working speed, tillage depth, and penetration angle. This method focuses on optimizing the soil subsoiling mechanism and subsoiler structure, primarily through static and dynamic analysis of the particle mixing degree after subsoiling, tillage efficiency, and the subsoilers under peak load. The specific process for optimizing soil characteristic parameters and subsoiler motion parameters is as follows:

[0056] Based on the soil deep loosening effect in step 3, the soil characteristic parameters and deep loosening tool motion parameters are changed, and the preprocessing operations are repeated according to steps 2 and 3 above. After the discrete element simulation corresponding to each set of parameters is completed, the soil deep loosening particle mixing degree and tillage efficiency are calculated, and the influence of soil characteristic parameters and deep loosening tool motion parameters on the soil deep loosening effect is analyzed.

[0057] Step 4: Based on DEM soil deep tillage simulation, analyze the tillage resistance experienced by the deep tillage cutters, and analyze the influence of soil characteristic parameters and deep tillage cutter motion parameters on the tillage resistance. Change the soil characteristic parameters and deep tillage cutter motion parameters, and analyze and calculate the tillage resistance experienced by the deep tillage cutters under different variables. The specific process is as follows:

[0058] Based on DEM soil deep tillage simulation, the Analyst module of EDEM post-processing was used to plot the resultant load (i.e., absolute soil tillage resistance) on the deep tillage cutter in various directions of the soil during the deep tillage process, as well as the tillage resistance on the deep tillage cutter in the X, Y, and Z axes of the soil after the resultant force decomposition, into curves of absolute soil tillage resistance and tillage resistance of each axis as a function of time. The stress situation and the reasons for the changes of the deep tillage cutter were analyzed.

[0059] Based on the soil characteristic parameters and deep tillage tool motion parameters changed according to the tillage resistance of the deep tillage tool in step 4, the preprocessing operations were repeated according to steps 2 and 4 above, and the calculations were performed again. After the discrete element simulation corresponding to each set of parameters was completed, the tillage resistance of the deep tillage tool was statistically analyzed, and the influence of soil characteristic parameters and deep tillage tool motion parameters on the tillage resistance of the deep tillage tool was analyzed.

[0060] Step 5: Using the tillage resistance obtained from the DEM as the load boundary condition for the FEM finite element analysis, static and dynamic analyses are performed to analyze the influence of tillage resistance on the subsoil cutter structure. Soil structure parameters and subsoil cutter structure parameters are varied, and the static and dynamic analysis results under different variables are analyzed and statistically analyzed. The specific process is as follows:

[0061] Since the output load includes both Pressure and Force loads, to more accurately apply the load to the surface of the subsoiler tool in the finite element analysis, the tillage resistance results from step 4 are output in Pressure format. The peak time of the resultant force load on the subsoiler tool is set as the start and end time. The output Pressure data is saved in .axdt format, and the position of the subsoiler tool at the peak load state is selected to be retained. The position of the subsoiler tool at the peak load is observed through the EDEM analysis module, and the position of the finite element model in ANSYS Workbench is adjusted to ensure that the coordinate systems of the DEM and FEM models are consistent in the finite element analysis. The adjusted subsoiler tool is saved as a .stl file as the model for the finite element analysis. The DEM Solutions module in ANSYS Workbench is used to read the output .axdt format Pressure load file, and it is associated and loaded into the Static Structural and Modal modules as the load boundary conditions for the finite element analysis. Pressure is applied to the structural surface of the subsoiler tool in contact with the soil when it is subjected to the peak load, and static and dynamic analysis of the subsoiler tool is performed.

[0062] The specific process of static analysis is as follows:

[0063] Open the Workbench module in ANSYS software, select the Discrete Element Simulation (DEM Solutions) module in the toolbar, drag the EDEM module to the Workbench main operation page → Results → Import the .axdt format Pressure load file as the load boundary condition for FEM analysis → Update to complete the setup of the EDEM simulation system.

[0064] Select the Analysis Systems module in the toolbar, drag the Static Structual module to the Workbench main operation page → Engineering Data → set the material, density, Poisson's ratio, and other parameters of the deep loosening tool, and keep them consistent with the parameters set in the Discrete Element Method software.

[0065] Import the deep tillage tool finite element model. In the Geometry section, locate the directory of the deep tillage tool finite element model and import it.

[0066] Connect the Results module in EDEM with the Setup module in Static Structural to associate the tillage resistance information when the subsoil cutter is subjected to peak load into the static analysis.

[0067] Add pressure as a load boundary condition: Static Structural → Imported Load → Inset → Pressure → Detail of “Imported Pressure” → Apply.

[0068] Add a Fixed Support constraint as a boundary condition. Static Structure → Insert Inset → Fixed Support → Detail of “Remote Displacement” → Apply.

[0069] Calculate the static analysis results, then proceed to Solution → Calculate Solve.

[0070] To view the static analysis results, go to Solution → Inset → Stress → Equivalent stress; then go to Solution → Inset → Deformation → Total Deformation → Total strain; and finally go to Solution → Update to obtain the stress and strain results for the deep loosening tool.

[0071] Compare the maximum stress σ of the deep-soil tool under peak load with the allowable stress [σ] of the deep-soil tool material. If σ ≤ [σ], then the deep-soil tool meets the strength requirements. Compare the maximum deformation ε of the deep-soil tool under peak load with the maximum allowable deformation [ε] of the material. If ε ≤ [ε], then the deep-soil tool meets the stiffness requirements.

[0072] The specific process of modal analysis is as follows:

[0073] To link the engineering data and model from static analysis to modal analysis, the Engineering Data and Geometry modules in Static Structural and Modal are connected accordingly.

[0074] Add a Fixed Support constraint as a boundary condition: Modal → Insert Inset → Fixed Support → Detail of “Remote Displacement” → Apply.

[0075] Analysis Settings → Detail of Analysis Settings → Max Modes to Find.

[0076] Calculate the modal analysis results, then proceed to Solution → Calculate Solve.

[0077] To view the modal analysis results, go to Solution → Graph → Select all → Create Mode Shape Results → Evaluate All Results. This will give you the natural frequencies and mode shapes of the deep loosening tool.

[0078] Comparison of natural frequencies ω i Using the natural frequency ω, determine whether the deep loosening tool resonates under the excitation of a relevant vibration source. If ω iIf the value is approximately ω, then the deep loosening tool structure needs to be modified. Compare the mode shapes of each order and observe whether the deep loosening tool breaks due to resonance, so as to make design modifications to the structural deformation of the deep loosening tool.

[0079] Based on the static and dynamic analysis results in step 5, the soil structure parameters and the deep tillage tool structure parameters are changed. The preprocessing operations are then performed again according to steps 1-5 above, and the calculations are repeated. After the discrete element simulation corresponding to each set of parameters is completed, the static and dynamic analysis results are statistically analyzed to determine the influence of tillage resistance on the deep tillage tool structure.

[0080] Step 6: Through DEM-FEM bidirectional coupled simulation, statistically compare the deep loosening effect when the deep loosening tool motion parameters are different under different soil characteristic parameters, and the static and dynamic analysis results when the deep loosening tool structural parameters are different under different soil structural parameters. Analyze the soil deep loosening mechanism and obtain the optimization results of deep loosening tool motion and structural parameters under different soil characteristic parameters.

Claims

1. A soil deep tillage simulation method based on DEM-FEM bidirectional coupling, characterized in that: Step 1: Define the structural parameters of the soil, establish a discrete element model of the soil DEM, define the structural parameters of the deep tillage tool, establish a three-dimensional model of the deep tillage tool, and mesh the three-dimensional model to obtain the finite element model of the deep tillage tool FEM. Step 2: Import the FEM finite element model of the deep tillage tool into the DEM discrete element model of the soil, define soil characteristic parameters for the DEM discrete element model of the soil, and define motion parameters for the FEM finite element model of the deep tillage tool. Step 3: Based on DEM soil deep loosening simulation, analyze the influence of soil characteristic parameters and deep loosening tool motion parameters on the soil deep loosening effect. Change the soil characteristic parameters and deep loosening tool motion parameters, and repeat steps 2 and 3. Step 4: Based on DEM soil deep tillage simulation, analyze the tillage resistance experienced by the deep tillage cutter, analyze the influence of soil characteristic parameters and deep tillage cutter motion parameters on the tillage resistance of the deep tillage cutter, change the soil characteristic parameters and deep tillage cutter motion parameters, and repeat steps 2 and 4. Step 5: Use the tillage resistance obtained from DEM as the load boundary condition for FEM finite element analysis, perform static and dynamic analysis, analyze the influence of tillage resistance on the deep tillage cutter structure, change the soil structure parameters and deep tillage cutter structure parameters, and repeat steps 1-5. Step 6: Analyze the deep loosening mechanism of soil through DEM-FEM bidirectional coupling simulation to obtain the optimization results of deep loosening tool motion and structural parameters under different soil characteristics and structural parameters.

2. The soil deep loosening simulation method according to claim 1, characterized in that: In step 1, the soil structure parameters include the number of layers and the space between particles in each layer, and the deep tillage tool structure parameters include the number of cutter heads, the thickness of the cutter heads, the arrangement of the cutter heads, and the installation angle of the cutter heads.

3. The soil deep loosening simulation method according to claim 1, characterized in that: In step 2, the soil's characteristic parameters include particle density, particle size, and particle number, while the deep tillage cutter's motion parameters include working speed, tillage depth, and entry angle.

4. The soil deep loosening simulation method according to claim 1, characterized in that: Step 3 simulates the deep tillage process of subsoilers in the soil, and analyzes and statistically analyzes the soil particle mixing degree and tillage efficiency under different variables: Using the Analyst module of EDEM post-processing, the number of soil particles in contact with each other in each layer during deep tillage was plotted as a curve. This allowed for the calculation of particle mixability by obtaining the changes in particle types in each soil layer after deep tillage. The formula for calculating particle mixability is as follows: In the formula, This represents the number of contact points between the two types of particles during deep loosening. This represents the number of contact points between the two types of particles after deep loosening. The number of bonding bonds broken between particles during deep tillage was plotted as a curve. The soil, originally compacted into clumps, was broken up and dispersed under the tillage of the deep tillage cutters. Therefore, the soil deep tillage efficiency can be obtained by calculating the slope of the curve in the direction of travel of the deep tillage cutters based on the curve. The formula for calculating tillage efficiency is as follows: In the formula, This represents the number of bonded keys broken at the start of deep loosening in the travel direction of the deep loosening tool. This represents the number of Bonding bonds that break at the moment deep relaxation is completed. This represents the start time of deep loosening by the deep loosening tool in the direction of travel. This marks the completion of Fukamatsu's work.

5. The soil deep loosening simulation method according to claim 1, characterized in that: In step 4, based on the DEM soil deep tillage simulation, the EDEM post-processing Analyst module is used to plot the absolute tillage resistance curve of the soil as a function of time, which is the resultant load of the deep tillage cutter on the soil in various directions during the deep tillage process. At the same time, the tillage resistance of the deep tillage cutter on the soil in the X, Y, and Z axes after the resultant force is decomposed is plotted as the tillage resistance curve of each axis as a function of time.

6. The soil deep loosening simulation method according to claim 1, characterized in that: In steps 5 and 6, DEM and FEM data coupling is implemented. The tillage resistance results from step 4 are output in Pressure format. The peak time of the resultant load on the subsoiler is set as the start and end time. The output load Pressure data is saved in .axdt format, and the position of the subsoiler at the peak load state is selected to be retained. The data includes the node ID number of the mesh element, the spatial coordinates of the node, and the element load. To ensure that the output load Pressure is accurately applied to the subsoiler, the position of the subsoiler at the peak load needs to be observed through the EDEM analysis module. The position of the finite element model in ANSYS Workbench is adjusted to ensure that the coordinate systems of the DEM and FEM models are consistent in the finite element analysis. The subsoiler with the adjusted position is saved as a .stl file as the model for finite element analysis. The EDEM module in ANSYS Workbench reads the output .axdt format Pressure load file, associates it with the Static Structural module as the load boundary condition for finite element analysis, and applies Pressure to the structural surface of the subsoiler in contact with the soil when it is subjected to the peak load. Static and dynamic analysis of the subsoiler is then performed.

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