The discrete element method (DEM), based on particle dynamics, is used to simulate the technological process of soil tillage using agricultural machinery. A key aspect of the DEM for obtaining accurate agrotechnical and energy indicators of soil cultivation is the formulation of particle contact rules, determined by normal and tangential interactions as well as cohesion forces. This study presents a comprehensive analysis of discrete element method (DEM) contact models used to simulate soil cultivation processes. This study addresses a key issue—the absence of a systematic approach to selecting adequate contact models, which limits the accuracy of predicting soil behavior during interaction with agricultural machinery. A detailed classification of 17 combinations of contact models implemented in the commercial software Rocky DEM was performed, grouped into three categories: normal force models (Linear Spring [LSP], Hysteresis [HLS], Hertzian [HSD]), tangential force models (Coulomb, linear spring limit [linear], Mindlin–Deresiewicz), and cohesive force models (linear cohesion [linear], constant force [constant], Johnson–Kendall–Roberts [JKR]). Experimental validation was conducted by analyzing the angle of repose for various soil types (sandy loam, light loam, medium loam, and heavy clay) with moisture contents ranging from 11 to 31%. This analysis identified the nine most effective combinations of contact models to describe normal, tangential, and cohesive forces (LSP–Coulomb–linear, HLS–linear–linear, HLS–Coulomb–linear, HSD–linear–linear, HSD–linear–JKR, HSD–Coulomb–linear, HSD–Coulomb–JKR, HSD–Mindlin–Deresiewicz–linear, HSD–Mindlin–Deresiewicz–JKR), which showed reliable agreement with experimental angle of repose measurements at approximately 85% accuracy. This study significantly contributes to advancing computer modeling methods in agriculture by providing a scientifically grounded approach for selecting DEM contact models.

The article presents the results of field studies to determine the quality and energy indicators of a modernized cultivator for strip tillage for industrial crops. An experimental setup with load cells with a nominal value of 30000 N is designed to measure the tractive resistance of the cultivator in the field. The result of the study is to establish the relationship between the cultivator traction resistance on the speed movement at various angles of spherical disks attack and the degree of crumbling on the structural and technological parameters of the cultivator. Various structural and technological parameters of the cultivator are the basis for measuring hectare fuel consumption.

The article presents the design of a cultivator with an automatic change in the stiffness of S-shaped racks, designed to improve the quality of tillage. The design of the cultivator is described, which includes rack stiffness regulators that automatically adapt to changes in soil hardness. The results of modeling the operation of the device are presented, confirming its effectiveness in ensuring a uniform depth of tillage.

This article examines the pressing issue of verifying contact models in the discrete element method (DEM) for modeling soil tillage processes. Due to the lack of a generally accepted methodology for selecting contact models for various soil types, a comprehensive study was conducted combining field experiments and numerical modeling. A verification method was developed and tested based on comparing experimental data on the draft resistance of a plow body with the results of calculations in the Rocky DEM 4.4 software package. The study yielded reliable experimental values for the draft resistance components and established the ranges of variation for their parameters. A comparative analysis of 10 promising combinations of contact models identified in previous studies was conducted. It was found that the improved Hertz-Mindlin model with the JKR adhesion model provides the best fit to the experimental results. Particular attention is paid to analyzing the influence of surface energy in the JKR model on changes in the rheological properties of the soil medium, which opens up the possibility of predicting soil behavior at different moisture levels. The results of the work are of practical value for the design and optimization of agricultural implements at the stage of their numerical modeling. The accuracy of predicting the draft resistance of the plow body during modeling for the studied soils at a moisture content of 18–25% ranged from 80 to 95%.