A method for representing boundaries in discrete element modelling - part II: Kinematics

The application of the DEM to engineering problems involving the dynamic be haviour of discontinuous media has necessitated the introduction of moving boundary surfaces. In this paper a method is presented for modelling three- dimensional moving boundary surfaces within the discrete element framework. The surfaces of boundary objects are discretized into triangular planar su rfaces using the finite wall method. Wall elements are grouped and each gro up is associated with a single discrete boundary object which may move inde pendently. Movement comprises any combination of translation and rotation o f wall element groups, subject to a given acceleration and velocity during a calculation cycle. The scheme is explicit due to rigidity of the wall ele ments which are stationary fixed in position and orientation over a time st ep. Any in-plane velocity is handled as a contact point velocity within a c alculation cycle. The kinematic conditions at each calculation cycle may be pre-defined or returned from a separate calculation of rigid body motion o f the boundary object. The method provides a means for coupling sphere-base d particle dynamics with rigid body dynamics and structural analysis of bou ndary components. Copyright (C) 2001 John Wiley & Sons, Ltd.