Construction of the discrete element bonding models for columnar granular organic fertilizers with different water contents

In order to construct a discrete element bonding model for columnar granular organic fertilizer with different moisture contents, this study calibrated the model parameters based on the Bonding model in the EDEM software. The maximum load-displacement data of the organic fertilizer were determined through uniaxial compression tests, establishing the relationship between moisture content and maximum load. Significant parameters were screened using the Plackett-Burman design, and parameter combinations were optimized through steepest ascent and Box-Behnken experiments. A mathematical model was established relating the maximum load to the Bonding parameters (normal stiffness, tangential stiffness, critical normal stress, critical tangential stress, and bonding radius) based on uniaxial compression simulation tests. Furthermore, a model was developed to predict the Bonding parameters based on the moisture content of the organic fertilizer, and the model’s accuracy was verified through experimental validation. The results show that the average error of the maximum load predicted by the model is 1.98%, which allows for the accurate construction of the bonding model for slurry granular organic fertilizer with different moisture contents, laying a foundation for the simulation study of the interaction between organic fertilizer and working components.