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.