Modelling of deformable structures in the general framework of the discrete element method

The discrete element method (DEM) is particularly suited for the numerical simulation of granular soils interacting with various types of deformable structures and inclusions. Numerous studies have been dedicated to the accurate modelling of particle shape, yet there is a lack of a general framework for modelling deformable structures of arbitrary shapes such as textiles, grids, membranes, tubes and containers. This paper presents a novel generalised approach to this problem in three dimensions. Minkowski sums of polytopes and spheres are used to describe the topology via three simple primitives: spheres, cylinders and thick facets. The cylinders and facets are deformable and can be connected to form grids and other membrane-like structures. A conventional elastic-plastic contact model is adapted to reflect all possible interactions. The implementation is verified by considering spheres moving along a complex membrane structure and a buckling tube. In addition, simulated pull-out tests on a grid and a membrane and bouncing tests of a hollow deformable sphere are reported. The versatility and capabilities of the approach and the potential applications to soil-inclusion problems are demonstrated. (C) 2015 Elsevier Ltd. All rights reserved.