CALIBRATION OF PARAMETERS FOR DISCRETE ELEMENT FRACTURED MODEL OF RICE STRAW AT THE APPROPRIATE HARVEST TIME

To address the lack of accurate and reliable straw models for simulating rice straw cutting, this study uses rice straw as the research object and constructs a discrete element model of straw using EDEM software to calibrate and optimize the bonding parameters. First, the physical parameters of rice straw were measured. For the bonding model parameters, a preliminary experiment was conducted to determine the range of bonding parameters, and the significance of each bonding parameter was analyzed using Plackett-Burman experiments to identify parameters with a significant impact on straw shear force. Then, a steepest climb test was conducted to determine the optimal combination of bonding parameters. Finally, a Box-Behnken simulation experiment was performed on the optimization interval, and a regression equation was established and solved to obtain the optimal parameter combination. The results show that the normal bonding stiffness, tangential bonding stiffness, and bonding radius have a significant impact on the straw shearing model. The optimal combination is 3.092×10¹⁰ Pa, 4.452×10¹⁰ Pa, and 0.496 mm. The established rice straw model is reliable and stable through multiple simulation experiments. This study provides an accurate and efficient method for optimizing the structure and motion parameters of rice straw crushing blades.