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Articles 1 - 11 of 11
Full-Text Articles in Civil and Environmental Engineering
Hexahedral Mesh Refinement Using An Error Sizing Function, Gaurab Paudel
Hexahedral Mesh Refinement Using An Error Sizing Function, Gaurab Paudel
Theses and Dissertations
The ability to effectively adapt a mesh is a very important feature of high fidelity finite element modeling. In a finite element analysis, a relatively high node density is desired in areas of the model where there are high error estimates from an initial analysis. Providing a higher node density in such areas improves the accuracy of the model and reduces the computational time compared to having a high node density over the entire model. Node densities can be determined for any model using the sizing functions based on the geometry of the model or the error estimates from the …
Automated All-Quadrilateral Mesh Adaptation Through Refinement And Coarsening, Bret D. Anderson
Automated All-Quadrilateral Mesh Adaptation Through Refinement And Coarsening, Bret D. Anderson
Theses and Dissertations
This thesis presents a new approach to conformal all-quadrilateral mesh adaptation. In finite element modeling applications, it is often desirable to modify the node density of the mesh; increasing the density in some parts of the mesh to provide more accurate results, while decreasing the density in other parts to reduce computation time. The desired node density is typically determined by a sizing function based on either the geometry of the model or the results of a finite element solution. Although there are numerous mesh adaptation methods currently in use, including initial adaptive mesh generation, node redistribution, and adaptive mesh …
Localized Coarsening Of Conforming All-Hexahedral Meshes, Adam C. Woodbury
Localized Coarsening Of Conforming All-Hexahedral Meshes, Adam C. Woodbury
Theses and Dissertations
Finite element mesh adaptation methods can be used to improve the efficiency and accuracy of solutions to computational modeling problems. For many finite element modeling applications, a conforming all-hexahedral mesh is preferred. When adapting a hexahedral mesh, localized modifications that preserve topologic conformity are often desired. Effective hexahedral refinement methods that satisfy these criteria have recently become available. However, due to hexahedral mesh topology constraints, little progress has been made in the area of hexahedral coarsening. This thesis presents a new method to locally coarsen conforming all-hexahedral meshes. The method works on both structured and unstructured meshes and is not …
Automated Quadrilateral Coarsening By Ring Collapse, Mark William Dewey
Automated Quadrilateral Coarsening By Ring Collapse, Mark William Dewey
Theses and Dissertations
In most finite element analysis, a uniform mesh is not the optimum way to model the problem. Mesh adaptation is the ability to modify a finite element model to include regions of the mesh with higher and lower node density. Mesh adaptation has received extensive study in both computational mechanics and computer graphics to increase the resolution or accuracy of the solution in specific areas. The algorithm developed in this thesis, the Automated Quadrilateral Coarsening by Ring Collapse (AQCRC) algorithm, provides a unique solution to allow conformal coarsening of both structured and unstructured quadrilateral finite element meshes. The algorithm is …
Conformal Refinement Of All-Hexahedral Finite Element Meshes, Nathan Harris
Conformal Refinement Of All-Hexahedral Finite Element Meshes, Nathan Harris
Theses and Dissertations
Mesh adaptation techniques are used to modify complex finite element meshes to reduce analysis time and improve accuracy. Modification of all-hexahedral meshes has proven difficult to the unique connectivity constraints they exhibit. This thesis presents an automated tool for local, conformal refinement of all-hexahedral meshes based on the insertion of multi-directional twist planes into the spatial twist continuum. The contributions of this thesis are (1) the ability to conformally refine all entities of an all-hexahedral element mesh, (2) the simplification of template insertion to multi-directional refinement. The refinement algorithm is divided into single hex sheet operations, where individual refinement steps …
Sculpting: An Improved Inside-Out Scheme For All Hexahedral Meshing, Kirk S. Walton
Sculpting: An Improved Inside-Out Scheme For All Hexahedral Meshing, Kirk S. Walton
Theses and Dissertations
Generating all hexahedral meshes on arbitrary geometries has been an area of important research in recent history. Hexahedral meshes have advantages over tetrahedral meshes in structural mechanics because they provide more accurate results with fewer degrees of freedom. Many different approaches have been used to create all-hexahedral meshes. Grid-based, inside-out, or superposition meshing all refer to a similar meshing approach that is a very common mesh generation technique. Grid-based algorithms provide the ability to generate all hexahedral meshes by introducing a structured mesh that bounds the complete body modeled, marking hexahedra to define an interior and exterior mesh, manipulating the …
Modification Of All-Hexadedral Finite Element Meshes By Dual Sheet Insertion And Extraction, Michael J. Borden
Modification Of All-Hexadedral Finite Element Meshes By Dual Sheet Insertion And Extraction, Michael J. Borden
Theses and Dissertations
The development of algorithms that effectively modify all-hexahedral finite element mesh is currently an active area of research. Mesh modification can be used to improve mesh quality reduce the time required to mesh a model, and improve the finite element analysis results. However, general modification of all-hexahedral meshes has proven difficult because of the global effects of local modifications. This thesis explains the global constraints on modifying all-hexahedral meshes and then presents three mesh modification techniques that make it possible to do local modifications while accounting for the global effects. These techniques are sheet insertion, sheet extraction, and mesh cutting. …
Surfacing Splicing: A Method Of Quadrilateral Mesh Generation And Modification For Surfaces By Dual Creation And Manipulation, Benjamin Todd Grover
Surfacing Splicing: A Method Of Quadrilateral Mesh Generation And Modification For Surfaces By Dual Creation And Manipulation, Benjamin Todd Grover
Theses and Dissertations
The effective generation high quality quadrilateral surface meshes is an area of important research and development for the finite element community. Quadrilateral elements generally lead to more efficient and accurate finite results. In addition, some all hexahedral volume meshing algorithms are based on an initial quadrilateral mesh surface mesh that has specific connectivity requirements. This thesis presents a new and unique procedure named "Surfaced Splicing". Surface Splicing allows for the generation of all quadrilateral surface meshes as well as the ability to edit these meshes via the dual. The dual contains the same data as the mesh but, unlike the …
Interval Matching And Control For Hexahedral Mesh Generation Of Swept Volumes, Jason F. Shepherd
Interval Matching And Control For Hexahedral Mesh Generation Of Swept Volumes, Jason F. Shepherd
Theses and Dissertations
Surface meshing algorithms require certain relationships among the number of intervals on the curves that bound the surface. Assigning the number of intervals to all of the curves in the model such that all relationships are satisfied is called interval assignment. Volume meshing algorithms also require certain relationships among the numbers of intervals on each of the curves on the volume. These relationships are not always captured by surface meshing requirements. This thesis presents a news technique for automatically identifying volume constraints. In this technique, volume constraints are grouped with surface constraints and are solved simultaneously. A sweepable volume has …
A General Three Dimensional All Quadrilateral Surface Mesh Generation Algorithm, Roger Cass
A General Three Dimensional All Quadrilateral Surface Mesh Generation Algorithm, Roger Cass
Theses and Dissertations
Among the available all-quadrilateral mesh generation algorithms progressive-front offers the best quality and robustness. The paving algorithm is a progressive-front technique that generates a two dimensional mesh of all quadrilaterals on planar surfaces. The technique is particularly suited to meshing irregular boundaries with interior holes. This thesis presents an extension of the paving algorithm to generalized three dimensional surfaces. The major problems in three-dimensional surface mesh generation are projection of nodes, calculation of interior angles, and connection of mesh fronts. The solutions to these problems are presented. This work is part of the ongoing CUBIT project at Sandia Labs. The …
Automatic Meshing Of Free-Form Deformation Solids, Ssuta S. Hsu
Automatic Meshing Of Free-Form Deformation Solids, Ssuta S. Hsu
Theses and Dissertations
Development of computer models and subsequent finite element analysis, are important aspects of modern engineering design. In this process, the geometry creation and finite element analysis software are well developed; however, the process of discretizing a geometry into a proper finite element model is time consuming and tedious. The work presented here uses the free-form deformation method to create smooth solid models, and invokes a solid subdivision and transition method to generate the hexahedron finite elements. The combination of these two techniques provides an automatic mesh generator that is easy to use, creates acceptable hexahedron elements for finite element analysis, …