Civil Engineering

Estimating Phase Durations for Chloride-Induced Corrosion Damage of Concrete Bridge Decks in Utah Kaylee Dee Bateman Department of Civil and Environmental Engineering, BYU Master of Science Chloride-induced deterioration of concrete bridge decks can be described in terms of three phases: 1) initiation of rebar corrosion, 2) rust formation and development of deck damage, and 3) accelerated deck damage towards structural failure. The first objective of this research was to investigate relationships among chloride concentration at the top mat of reinforcing steel, deck age, cover depth, and occurrence of delamination for concrete bridge decks with selected surface treatments and rebar types. Relating these factors can help establish greater understanding about the duration of each phase of the deterioration process. A second objective of this research was to investigate the relationship between chloride concentrations that develop between the bars and those that develop directly above ...

Steven J. Owen, Scott A. Canann and Sunil Saigal ... For example, in Figure 4, the tetrahedron initially defined by nodes ABN 1 -N 2 becomes two tetrahedra defined by CBN 1 -N 2 and ACN 1 -N 2 . A new pyramid element can then be formed from the nodes AN n -BN 1 -C. The ...

... Mid-Node Admissible Space for 3D Quadratic Tetrahedral Finite Elements AZI Salem, S. Saigal and SA Canann ... Babuska and Aziz [3] proposed the maximum angle con-dition, and also showed that the minimum angle condition [4–6] is not essential. ...

A method is presented for meshing 3D CAD surfaces in parametric space using an advancing front approach and a metric map to govern the size and shape of the triangles in the parametric space. The creation of the metric map will be discussed. The advanc ing front mesher generates triangles based on the metric map, stretching them in order to

Schneiders and Debye (1995) present two algorithms for quadrilateral mesh refinement. These algorithms refine quadrilateral meshes while maintaining mesh conformity. The first algorithm maintains conformity by introducing triangles. The second algorithm maintains conformity without triangles, but requires a larger degree of refinement. Both algorithms introduce nodes with non-optimal valences. Non-optimal valences create acute and obtuse angles, decreasing element quality. This paper presents techniques for improving the quality of quadrilateral meshes after Schneiders' refinement. Improvement techniques use topology and node valence optimization rather than shape metrics; hence, improvement is computationally inexpensive. Meshes refined and subsequently topologically improved contain no triangles, even though triangles are initially introduced by Schneiders' refinement. Triangle elimination is especially important for linear elements since linear triangles perform poorly. I...

A method and system for generating an unstructured automatic mesh and executing computational algorithms using a finite element numerical approach is disclosed. The method is to model a hydrocarbon reservoir, wells, and completions as a single system, accounting for static information and transient behavior of wells, hydraulic fractures and reservoirs in a single model.

The numerical solution of problems in science and engineering via the finite element method requires, as a first step, the discretization of a domain into a set of simply shaped elements. Determining the size of these elements along the domain, including the boundary, to form well-shaped elements is a difficult task. We present in this paper a simple technique, called smart sizing, which automatically computes high quality initial element sizing on curves for triangular, quadrilateral and tetrahedral elements. Curve divisions are computed based on curve and surface curvatures as well as feature proximity. In the three dimensional case, refinement of facets is performed as needed to create reasonably sized surface elements. Computing a boundary mesh appropriately is a key step to successfully determine the size and distribution of new elements towards the interior of the domain, especially for the advancing front and constrained Delaunay meshing techniques.

. Automatic finite element mesh generation techniques have become commonly used tools for the analysis of complex, real-world models. All of these methods can, however, create distorted and even unusable elements. Fortunately, several techniques exist which can take an existing mesh and improve its quality. Smoothing (also referred to as mesh relaxation) is one such method, which repositions nodal locations, so as to minimize element distortion. In this paper, an overall mesh smoothing scheme is presented for meshes consisting of triangular, quadrilateral, or mixed triangular and quadrilateral elements. This paper describes an efficient and robust combination of constrained Laplacian smoothing together with an optimization-based smoothing algorithm. The smoothing algorithms have been implemented in ANSYS and performance times are presented along with several example models. Keywords. Smoothing, Laplacian smoothing, optimization-based smoothing, triangular, quadrilateral, quaddominan...

A method for solving space-time problems involving three-dimensional space wherein an unstructured four-dimensional finite element model is generated and solved to produce a four-dimensional solution. The four-dimensional mesh is generated from a three-dimensional mesh by extruding each of the simplices of the three-dimensional mesh in a time dimension. The four-dimensional prisms formed by extrusion of the three-dimensional simplices are divided into a plurality of four-dimensional simplices which form a four-dimensional finite element model. The elements of the four-dimensional model can be selectively refined to obtain a finer mesh in areas of greater interest, and a coarser mesh in areas which are of less interest. The mesh can be refined in the spatial dimensions and also in the temporal dimension.

Automatic finite element mesh generation of CAD generated data has been a goal of finite element meshing codes for years. However, the lack of accuracy and the amount of detail in this data have made this a daunting task. In essence, the CAD data needs to be defeatured to overcome accuracy deficiencies and to remove excessive detail. In this pape