Keywords: distributed visualization, propagating cracks, local Voronoi decomposition, discrete element method, VisPartDEM.

Lattice-based discrete element models are extensively applied for parallel simulation of heterogeneous solids to study their dynamic deformation behaviour and fracture problems. However, particle systems modelled using the discrete element method (DEM) have no permanent connections or usual grid that can be employed by usual visualization techniques. Initial defects are identified between pairs of neighbouring particles on the lattice connections. One-dimensional connections are not suitable for standard visualization techniques in two or three dimensions. Moreover, there is no direct technique to form the geometry of a propagating crack from the initial defects and visualize the crack surface. The usual surface extraction algorithms cannot be applied because of the absence of suitable field data defining the crack surface. In most cases, cracks and related phenomena are simply visualised by coloured lattice connections or particle positions [1,2].

A distributed algorithm based on feature extraction is developed for the analysis of crack geometry. Local Voronoi decompositions are generated according to the lattice topology employed in the computations. Contact surfaces of neighbouring particles are defined using the faces of the generated Voronoi cells. Initial defects identified between pairs of neighbouring particles are mapped on contact surfaces. Geometric representation of a crack using contact surfaces is sufficently accurate and has clear physical meaning. The algorithm developed for the analysis of the surface geometry and visualization of the propagating cracks is implemented in the VisPartDEM software. It is a distributed visualization software for large particle systems simulated using the discrete element method. The distributed architecture of VisPartDEM is designed for interactive visualization on different infrastructures such as gLite grids, rock clusters and graphics workstations.

Datasets obtained by solving the elastic solid problem exhibiting non-uniform distribution of fracture force values are considered as visualization benchmark. Performed benchmark illustrated that the developed algorithm was able to visualize the crack geometry and fracture process modelled in mono-dispersed particulate media. Performance analysis revealed that generation of local Voronoi diagram consumed 34.5% and 40.8% of the total benchmark time in tow and three dimensions, respectively. The performed quantitative comparison showed that the developed software significantly outperformed a code based on the global Voronoi algorithm.

1

G. Lilliu, J.G.M. Van Mier, "3D lattice type fracture model for concrete", Engineering Fracture Mechanics, 70(7-8), 927-941, 2003.

2

A. Kaceniauskas, R. Kacianauskas, A. Maknickas, D. Markauskas, "Computation and visualization of discrete particle systems on gLite-based grid", Advances in Engineering Software, 42(5), 237-246, 2011

purchase the full-text of this paper (price £20)

go to the previous paper
go to the next paper
return to the table of contents
return to the book description
purchase this book (price £40 +P&P)