Modelling the interaction of a deep tillage tool with heterogeneous soil

Numerical simulation of soil-tool interactions is a cost-effective method to assess and gain insight into the tool performance as affected by working parameters. In this study, a discrete element model (DEM) was developed to simulate a deep tillage tool and its interaction with soil to address the stratified soil layers in agricultural fields using the Particle Flow Code in Three Dimensions (PFC3D). Sensitivity analysis was performed to determine the most critical set of model parameters which affected the soil dynamic behaviors. With test data, this set of model parameters was calibrated using a systematic scheme that featured response surface optimization and inverse solution technique to minimize the discrepancy between simulations and measurements. The model was validated and then utilized to investigate the effects and the optimal value of the working depth. The results showed that the particle stiffness and bond stiffness were the most influential model parameters and the calibrated values were 6.43 × 1 N m−1 and 2.62 × 1 Pa m−1, respectively. The calibrated model was capable of predicting soil cutting resistance and soil disturbance characteristics with relative errors ranging from 2.63 to 10.2%. Simulation results indicated that the when the deep tillage tool works at either 5 or 20 mm deeper than the hardpan layer, the best performance for breaking the hardpan could be achieved. The proposed model can facilitate the investigation of interactions between soil engaging tools and heterogeneous soil.