  For a wide range of applications, we need DEM simulations of granular matter
in contact with flexible elastic boundaries. We present a novel method to
describe the interaction between granular particles and a flexible elastic
membrane. Here, the standard mass-spring model approach is supplemented by
surface patches given by triangulation of the membrane. In contrast to standard
mass-spring models, our simulation method allows for an efficient simulation
even for large particle size dispersion. The novel method allows coarsening of
the mass-spring system leading to a substantial increase in computation
efficiency. The simulation method is demonstrated and benchmarked for a
triaxial test.
