Abstract:Regarding the challenge of constructing a discrete element model for the thin-walled leaves of rice pot seedlings, which limits the simulation analysis of pneumatic seedling throwing due to the lack of a suitable leaf model to characterize the effect of seedling posture changes on its trajectory under the interaction between flexible leaves and airflow fields, taking rice pot seedlings at the three-leaf and one- heart stage as the research object, a reverse reconstruction method for the discrete element model of seedling leaves was proposed based on multi-view image fitting. This method discretized the continuous contour of the leaves using unit grids, mapped the spatial morphological relationships of the leaves into particle coordinate information, and constructed a discrete element model of the flexible leaves of rice pot seedlings based on the Hertz-Mindlin with Bonding V2 contact model. Using the relative deflection of the flexible leaves as the evaluation index, the parameters affecting leaf relative deflection were screened for significance through a Plackett-Burman design. A second-order regression model for leaf relative deflection was established based on a Box-Behnken design. It was clarified that normal stiffness per unit area, tangential stiffness per unit area, and bonding ratio significantly affected leaf relative deflection. Simulation tests performed with the calibrated parameters showed a relative error of 2. 51% between the simulation and physical experiment, verifying the validity of the constructed model. The research result can provide a reference for the subsequent development of discrete element models suitable for simulating pneumatic seedling throwing.
