Determination of Characteristics and Establishment of Discrete Element Model for Whole Rice Plant

Abstract

In order to accurately establish a discrete element model for the whole plant flexibility of upright rice during the harvesting period, several physical characteristics, such as geometric features, moisture content, and density, of the entire rice plant were measured, along with frictional properties, such as the static and rolling friction coefficients, and mechanical properties, including the elastic modulus and restitution coefficient. A flexible and upright discrete element model of the rice plant was established using the DEM method based on the Hertz–Mindlin (no slip) and Hertz–Mindlin with bonding mechanical models. The parameters were optimized through Plackett–Burman screening experiments, steepest ascent experiments, and Box–Behnken optimization experiments to accurately determine the discrete element model parameters of each component of the rice plant. The calibration process of the contact parameters between rice grains and steel was analyzed in detail as an example, resulting in a calibration error of 0.68% for the natural repose angle. Taking the calibration of the contact parameters between the main stem and steel as an example, a detailed analysis of the calibration process was conducted. The calibration resulted in a calibration error of 2.76% for the natural repose angle and 2.33% for deflection. This study lays the foundation for understanding the mechanical response of rice and machinery when they are coupled together. Additionally, it provides valuable references for establishing discrete element models of plant species other than rice.

Influence of Shaped Hole and Seed Disturbance on the Precision of Bunch Planting with the Double-Hole Rice Vacuum Seed Meter

“…The restitution coefficient, static friction coefficient, and rolling friction coefficient between seed and seed meter are 0.25, 0.5, and 0.01, respectively. The restitution coefficient, static friction coefficient, and rolling friction coefficient between seed and seed meter are 0.52, 0.48, and 0.01, respectively [28]. Discrete element simulations were performed to obtain the total force magnitude of the seed for different meter discs, as shown in Figure 15a.…”

Analysis of the Interaction Mechanism between Preharvest Threshing Device and Rice at Harvesting Period Based on DEM Simulations and Bench Tests

“…The relevant parameters of the entire-plant rice discrete element model were acquired through reference to the relevant literature or further calculated based on the available data. The specific values are outlined in Table S1 [15,20,22,27,28].…”

“…In [21], Liu et al used the constructed discrete element flexible stalk model to investigate the impact of different threshing gaps on rice straw damage and conducted bench tests to validate the results. Xu et al [22] conducted measurements and calibrations of the key mechanical parameters, which they then used to construct an entire rice plant model using the discrete element method. The studies mentioned above highlight that the discrete element method can successfully simulate and reproduce the interactive mechanisms between agricultural machinery and crops, yielding reliable experimental data.…”