Determination and verification of parameters for the discrete element modelling of single disc covering of flexible straw with soil

Knowledge of the interaction of straw and soil is the basis for optimising no-till seeding components. However, straw as a flexible material lacks accurate and reliable discrete element simulation parameters. In this paper, the discrete element parameters of flexible straw and soil are calibrated respectively and a discrete element model for flexible straw mulch soil model was established. The straw double-layer bond model and soil model were modelled using the Hertz-Mindlin with bonding particle contact model in the EDEM discrete element simulation software. The maximum shear force of straw was used as the experimental indicator and the parameters of the model were calibrated. Due to the isotropic distribution of the cohesive force between soil particles, normal and tangential stiffnesses were set to be equal, with the critical normal stress equal to the critical tangential stress, using the accumulation angle of soil as the experimental indicator, the parameters of the model were calibrated. Both simulation and experiment were performed using the established straw mulch soil model and the single disc opener. Under the best conditions with an operating speed of 6 km h−1 and a furrowing depth of 120 mm, the straw shearing rate of both simulation and soil bin experiments was 100%, with a relative error of 21% in the forward sliding distance of the straw, 9% in the average draft force of the opener, and 13% in the downforce.