Automated simulation of arbitrary, non-planar, 3D crack growth in real-life engineered structures requires two key components: crack representation and crack growth mechanics. A model environment for representing the evolving 3D crack geometry and for testing various crack growth mechanics is presented. Reference is made to a specific implementation of the model, called FRANC3D. Computational geometry and topology are used to represent the evolution of crack growth in a structure. Current 3D crack growth mechanics are insufficient; however, the model allows for the implementation of new mechanics. A specific numerical analysis program is not an intrinsic part of the model; i.e., finite and boundary elements are both supported. For demonstration purposes, a 3D hypersingular boundary element code is used for two example simulations. The simulations support the conclusion that automatic propagation of a 3D crack in a real-life structure is feasible. Automated simulation lessens the tedious and time-consuming operations that are usually associated with crack growth analyses. Specifically, modifications to the geometry of the structure due to crack growth, re-meshing of the modified portion of the structure after crack growth, and re-application of boundary conditions proceeds without user intervention.

This paper deals with the problem of creating and maintaining a spatial

We introduce HPS, a new topological data structure that efficiently represents hierarchies of planar subdivisions, thus providing direct and efficient support for GIS concepts such as abstract generalizations and multi-scale partitions. Unlike previous ad hoc solutions, HPS provides efficient access to adjacency information for each level and across levels, while storing the complete hierarchy in a single data structure, without duplications. HPS also provides topological operators that ensure global consistency. Like all topological data structures, HPS can be used as a framework onto which geometric and attribute information is placed: HPS explicitly handles attributes consistently with modeling, and naturally supports both topological and geometrical multi-resolution representations. We also discuss how some typical applications in GIS, Digital Cartography, and Finite Element mesh generation can be improved with HPS. keywords: topological data structures, hierarchical modeling, mul...

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A three-dimensional parallel environment for finite element method (FEM) analysis is presented. This environment is comprised by integrated computer programs, each of one responsible for a different task: pre-processing, mesh generation, structural analysis and post-processing. In this work, this entire system is presented, with more emphasis to volumetric mesh generation and FEM analysis that could be performed in a parallel way. A program named FRANC3D (3D Fracture Analysis Code) [1][2] is used in the preprocessing step. The volumetric mesh is generated using a algorithm that combines an advancing front technique with a recursive spatial decomposition technique, in this case an octree, to define the internal nodes, element sizes, and mesh transition [3]. A strategy to parallelize this algorithm is also presented. An existing finite element method program, called FEMOOP (Finite Element Method – Object Oriented Programming) [4] has been adapted to implement the parallel features. The parallel analysis can be performed using two different techniques: a domain decomposition technique or an element-by-element scheme. Both are presented in this work. Finally, analyses of three-dimensional models are used to test the performance and reliability of this parallel system. 1

We introduce HPS, a new topological data structure that e ciently represents hierarchies of generalizations and multi-scale partitions. Unlike previous ad hoc solutions, HPS provides e-cient access to adjacency information for each level and across levels, while storing the complete hierarchy in a single data structure, without duplications. HPS also provides topological operators that ensure global consistency. Like all topological data structures, HPS canbeusedas a framework onto which geometric and attribute information is placed: HPS explicitly handles attributes consistently with modeling, and naturally supports both topological and geometrical multi-resolution representations. We also discuss how some typical applications in GIS, Digital Cartography, and Finite Element mesh generation can be improved with HPS.

Abstract. To perform crack propagation in a solid model, a high computational power is required, mainly at three-dimensional mesh generation and structural analysis steps. At each crack propagation step, the mesh is rebuilt and a new structural analysis is performed. If a large scale cracked model is being analyzed, time consumed by mesh generation and analysis may be extremely large or even prohibitive in some cases. The main idea of the methodology presented in this work is to parallelize mesh generation and structural analysis procedures, and to integrate these procedures into a computational environment able to perform automatic arbitrary crack propagation. A parallel mesh generation algorithm has been developed. This algorithm is capable of generating three-dimensional meshes of tetrahedral elements in arbitrary domains with one or multiple embedded cracks. A finite element method program called FEMOOP, based on object oriented programming, has been adapted to implement the parallel features. The parallel strategy to solve the set of linear equations is based on an element-by-element scheme in conjunction with a gradient iterative solution. A program called FRANC3D, which is completely integrated with other components of the system, performs crack propagation and geometry updates. The entire system is described in this work and an application example is presented to show the performance and reliability of the crack propagation process.

This paper deals with the problem of creating and maintaining a spa-tial subdivision, defined by a set of surface patches. The main goal is to create a set of functions which provides a layer of abstraction capable of hiding the geometric and topological problems which occur when one cre-ates and manipulates spatial subdivisions. The study of arbitrary spatial subdivisions extends and unifies the techniques used in nonmanifold solid modeling and allows the modeling of heterogeneous objects.