Flexible polyhedra modeled by the virtual element method in a discrete element context

Systems composed of numerous particles, as granular materials, can be simulated by the discrete element method (DEM). There are numerous versions of DEM considering particle shapes as spheres, superellipsoids, polyhedra and others. Classically, particles are considered rigid and the only flexibility present in the model is local, embedded in the contact interface model. Such treatment seems not to be adequate when one is interested in simulating phenomena dependent on the general flexibility of particles and investigating their effects in granular media. The present work proposes a method to introduce flexible particles of polyhedral shape within the DEM context. We employ the Virtual Element Method (VEM) for the spatial discretization of particles, taking advantage of its geometrical versatility, modeling each particle with a single-element. The dynamical behavior of the resulting particle system is predicted using an implicit time-integration. Contact between polyhedral particles (possibly non-convex) is addressed by the master–master contact technique and its degenerations, employing a barrier-based interface law. Examples include studies and discussions on the VEM's stiffness and mass stabilization parameters, such as simulations of systems composed of flexible polyhedral particles as a sand-material pack under compression and a hopper discharging process.