2.4.1. Selection of the Contact Model

In this study, Q235A steel was used as the contact material for both the ramie phloem and ramie xylem in the physical tests. Since there was no adhesion between the phloem and xylem and the steel plate during the physical tests, and there was no significant deformation during the accumulation process, the phloem and xylem were idealized as rigid bodies without considering their mechanical properties, only exploring their contact relationship. Therefore, the Hertz–Mindlin (no slip) contact model was selected for the discrete element simulation. The contact parameters included the coefficient of restitution, coefficient of static friction, and coefficient of rolling friction between the phloem and Q235A steel, phloem and phloem, phloem and xylem, xylem and Q235A steel, and xylem and Q235A xylem.
