Discrete element method to simulate continuous material by using the cohesive beam model

Abstract

The mechanical behavior of materials is usually simulated by the continuous mechanics approach. However, simulation of non-continuous phenomena like multi fracturing is not well adapted to a continuous description. In this case, the discrete element method (DEM) is a good alternative because it naturally takes into account discontinuities. Many researchers have shown interest in this approach for wear and fracture simulation. The problem is that, while DEM is well adapted to simulate discontinuities, it is not suitable to simulate continuous behavior. In problems of wear or fracture, material is composed of continuous parts and discontinuous interfaces. The aim of the present work is to improve the ability of DEM to simulate the continuous part of the material using cohesive bond model. Continuous mechanics laws cannot be used directly within a DEM formulation. A second difficulty is that the volume between the discrete elements creates an artificial void inside thematerial. This paper proposes a methodology that tackles these theoretical difficulties and simulates, using a discrete element model, any material defined by a Young’s modulus, Poisson’s ratio and density, to fit the static and dynamic mechanical behavior of the material. The chosen cohesive beam model is shown to be robust concerning the influence of the discrete element sizes. This method is applied to a material which can be considered as perfectly elastic: fused silica.