Modeling contact interactions between triangulated rounded bodies for the discrete element method

• We describe a method to calculate contact forces between arbitrary rounded bodies.
• Bodies are represented as triangulated surfaces with associated radii of curvature.
• Contact forces are calculated by integrating Hertz contact pressure.
• For spheres, convergence towards the Hertz solution upon mesh refinement is shown.
• Gravitational packing of spheres, pears and gummy bears is shown as an example.

Calculating contact forces between complex shapes for performing Discrete Element Method (DEM) simulations is a long standing problem with no unique ideal solution. In this work, a new method to calculate interactions between arbitrary rounded bodies is presented. Each body is represented by a triangulated surface mesh, in which each triangle is associated with a unique radius of curvature. Then, normal contact forces are calculated by numerically integrating a (Hertz) contact pressure formulation over the contact area between two contacting particles. This results in a mechanistic contact description that is converging with refinement of a given triangulation and directly uses physical material properties as parameters of the contact model. After showing convergence upon mesh refinement towards the Hertzian solution, the error for non-spherical curvatures is investigated and the new model is compared with an indentation experiment of a pear-shaped object. Finally, the method is demonstrated in a simulation of gravitational packing by simulating packing of spheres, pear-shaped as well as gummy bear-shaped objects.