On Mesh Independence in Dynamic Fracture Analysis by Means of the Discrete Element Method

Abstract

The authors successfully applied the so-called Discrete Element Method (DEM) to determine the dynamic response of concrete and rock structures that fracture under the action of static and dynamic loading. When on account of the size of the model larger elements must be employed, the issue of mesh objectivity must be addressed. In response determinations of structures with initial cracks or high stress gradients, which result in fracture localization, well established procedures lead to results that are mesh independent. However, in elements subjected to approximately uniform stress fields a hitherto unknown problem arises in the analysis of non-homogeneous materials: the need to know a priori the degree of fracturing of the element. This should also affect finite element analysis in cases in which there is no clear fracture localization.
Within this context, in this paper a scheme to circumvent this difficulty is suggested by the authors. The applicability of the proposed solution is tested in several numerical examples involving large concrete or rock structures.