Y-GUI: A graphical user interface and pre-processor for the combined finite-discrete element code, Y2D, incorporating material heterogeneity

Numerical modelling of a discontinuous medium has gained much popularity in recent decades. The combined finite-discrete element method (FEM/DEM) is a state-of-the-art numerical modelling technique pioneered in the mid-1990s. Y2D is a robust two-dimensional FEM/DEM research code developed by Munjiza in 2004. The major limitations of this code are (1) the lack of a graphical user interface (GUI) meaning that all pre-processing has to be made directly on an ASCII input file and (2) the inability of dealing with heterogeneous media. This contribution presents the first GUI and pre-processor, known as Y-GUI, developed for Y2D and the implementation of a new algorithm that allows for the use of heterogeneous materials. In the text all major FEM/DEM concepts are described, together with the main features available in the Y-GUI. The use of Y-GUI is presented in detail and some of its functionalities, including the heterogeneity module to be used to randomly assign materials to a mesh, are introduced. At the end of the manuscript, four case studies, including Brazilian tests of a homogeneous and a layered rock sample and a rock avalanche, are presented.