Mechanical behavior of normal and rotten corn stalks: Experiment and simulation on particles transformation in different layers based on the discrete element method

The effect of stalk cutting directly influences the quality of field seeding in the process of no-till seeding. This study established a discrete element method (DEM) model of corn stalks to analyze its mechanical behavior during the cutting process. The mechanical properties of normal and rotten corn stalks were determined with experiment. The tensile force of normal stalk rind is 15.59% higher than that of rotten one, which compares with an increase of 52.49% for inner tissue. The bending strength of the normal stalk rind is 68.61% higher than that of rotten stalks, and then the bending strength of the inner tissue is 58.77% higher than that of rotten stalks. Additionally, the shearing force of normal inner tissue is 67.65% higher than that of rotted stalks. The processes of cutting and bending for stalk were analyzed through simulation and experiment. The bending force of stalks in physical tests is 241 N, which the error between simulation and physical tests is 1.24%. The shear force of stalks in physical tests is 571N, which the error is 5.43%. Digital image correlation (DIC) was applied to analyze strain distribution during deformation, which shows that bending strains ranged from 0 to 2.9796, and shear strains ranged from 0 to 24.8745. The results indicate that normal corn stalks have superior mechanical properties to rotten ones. This study provides a theoretical foundation for design of no-till seeding machine.