A polybézier-based particle model for the DEM modeling of granular media

Abstract

The discrete element method (DEM) has become a prominent tool for modeling granular media, whereas the development of versatile and efficient particle models for the modeling of irregular-shaped particles remains a heated topic and challenge. In this work, a new particle model based on polybézier curves to describe particle shapes is proposed for the modeling of smooth and irregular-shaped particles. In particular, cubic bézier curves are adopted because they have a fairly high degree of freedom in modeling curved geometries as well as a closed-form support function. With the particle geometry and support function derived from cubic polybézier curves, the Gilbert-Johnson-Keerthi algorithm is adopted to detect contacts, and the expanding polytope algorithm is adopted to resolve contact geometric features. To generate polybézier-based particle templates from images of particle shapes, a particle swarm optimization-based geometric fitting procedure is also developed. The effectiveness of the proposed particle model for shape representation is validated using a chart of particle shapes with various roundness and sphericity characteristics. DEM simulations of random packing and biaxial compression tests on polydispersed irregular-shaped particles are also presented, and the results show that the proposed model has fairly good computational efficiency and numerical stability.