Modeling the fracture process of wheat straw using a discrete element approach

The cracking and breaking of wheat straw under the action of external force are rarely studied, they affect the precision of its simulation using the discrete element method. The process of straw change due to cracking and breaking consists of two stages: ring collapsing and breaking. In order to restore the real process of straw change, this study develops a discrete element model based on the Hertz-Mindlin bonding V2 contact model. The bond parameters were calibrated using the test of compression, shear, and three-point bending. An orthogonal experiment was conducted to determine the optimal parameter combination. The obtained results showed that the proposed straw model accurately simulated the cracking, breaking, and flow characteristic. The relative errors of compression strength, shear strength, and deflection were 9.48, 8.74, and 11.51%, respectively. The relative error of the angle of repose (AOR) was only 1.67%, which indicates that the mechanical properties and flow characteristic of the model are consistent with those of real straw. This study holds significant importance in accurately replicating the authentic straw treatment process in the field.