Investigation of tractor parameters on performance and discrete element method modelling

This study applies the Discrete Element Method (DEM) to quantify the tractive performance of a Goldoni 240 tractor tire under varying operating conditions, including three drive configurations of 4WD, RWD, FWD, three tire inflation pressures of 170, 200, 230 kPa, and three ballast levels of 0, 60, 120 kg, while maintaining a constant drawbar pull of 2 kN. Main objective was to rigorously assess and validate three widely used DEM soil–tire contact models—Hertz–Mindlin (HMCM), Hysteretic Spring (HSCM), and Hertz–Mindlin with JKR adhesion (HMCM–JKR) to determine their suitability for simulating cohesive soil behavior. Field and simulation results showed that the 4WD configuration consistently produced the lowest drive-wheel slip, maintaining values within the agronomically recommended range of 10–15% under the 2 kN load. Increasing inflation pressure resulted in higher slip due to reduced tire–soil contact area across all drive systems; however, 4WD remained less sensitive to inflation pressure, with slip at 230 kPa still lower than that of RWD and FWD at 170 kPa. Ballasting effectively reduced slip, with the 120 kg ballast providing the greatest improvement for all configurations. Model validation showed that the Hysteretic Spring Contact Model (HSCM) exhibited the strongest linear relationship with the experimental measurements among the investigated contact models, with the highest correlation coefficients across the evaluated operating conditions. These results indicate a stronger statistical relationship between the HSCM responses and the experimental observations compared with the HMCM and HMCM–JKR models. However, the regression and ANOVA results are interpreted as measures of relative model performance rather than as evidence of exact numerical agreement between DEM predictions and experimental measurements. Overall, the DEM framework provides a useful numerical approach for investigating tire–soil interaction under the operating conditions considered in this study.