Engineering Commons^™

Numerical Analysis Of Passive Force On Skewed Bridge Abutments, Zifan Guo

Theses and Dissertations

Accounting for seismic forces and thermal expansion in bridge design requires an accurate passive force-deflection relationship for the abutment wall. Current design codes make no allowance for skew effects on passive force; however, large scale field tests indicate that there is a substantial reduction in peak passive force as skew angle increases. A reduction in passive force also reduces the transverse shear resistance on the abutment. The purpose of this study is to validate three-dimensional model using PLAXIS 3D, against large scale test results performed at Brigham Young University and to develop a set of calibrated finite element models. The …

Multiple Point Constraint (Mpc)-Based Variable Node Super-Element, Mohamad Eftekharjoo

Mechanical & Aerospace Engineering Theses & Dissertations

The multiple point constraint (MPC)-based variable node element is introduced in this study to handle mismatched meshes between sub-domains in finite element analysis. The MPC-variable node element is a collection of a group of elements. The compatibility condition along the interface boundary is imposed along the edge of these elements through Lagrange multipliers. The Elimination method is then used to remove the effects of the dependent nodes in these elements to produce a single MPC-based variable node element. The derived variable node elements are applied to solve two plane strain problems in order to validate the accuracy of the proposed …

Finite Element Analysis Of Effective Mechanical Properties Of Hierarchical Honeycomb Structures, Ninad Gandhi

All Theses

Honeycomb structures are widely used in engineering applications mainly due to their high strength to weight ratio. By changing the base material and geometry of the repeating unit cell structure, target effective properties can be achieved. Hierarchical honeycomb structures are known to have enhanced mechanical properties when compared to regular honeycomb structures. Therefore, it is important to understand and quantify the mechanical properties and the variation of these properties with the presence of hierarchy. This investigation builds upon prior work and considers the mechanical properties of two dimensional hierarchical honeycomb structures. Previous research of hierarchical honeycomb structures studied replacing the …

A Finite Element Analysis Of Tibial Stem Geometry For Total Knee Replacements, Aaron Isidro Bautista

Master's Theses

The purpose of this study was to investigate the influence of tibial stem geometry on stress shielding of the tibia for patients with a total knee replacement. Finite element analysis was used to study different tibial stem geometry types, as well as a vast array of different geometric sizes. Both a peg and stem type geometry were analyzed and compared in order to determine what type geometry causes the least amount of stress shielding. A static loading condition with a dynamic loading factor of three was used for the system and the stress responses were analyzed at regions of interest …

Ligament Model Fidelity In Finite Element Analysis Of The Human Lumbar Spine, Mitchell Scott Hortin

Theses and Dissertations

The purpose of this project is to quantify the effects of increasing spinal ligament fidelity on the mechanics of the human lumbar spine using finite element analysis (FEA). In support of this goal, a material characterization study was completed to provide anisotropic, nonlinear material parameters for the human anterior longitudinal ligament. (ALL). Cadaveric samples of the human ALL were tested using a punch test technique. Multi- axial force-deformation data were gathered and fit to a commonly used transversely isotropic material model using an FEA system identification routine. The resulting material parameters produced a curve that correlated well with the experimental …

Osteoarthritis Induced Glenoid Morphology And Bone Quality: An Evaluation Of Augmented Glenoid Components, Nikolas K. Knowles

Electronic Thesis and Dissertation Repository

Osteoarthritis of the glenoid results in regional bone density variations and bone loss that may compromise early component fixation and support. The two common morphologies, symmetric and asymmetric erosion, were characterized by bone density and morphology, and assessed on the basis of bone removal and bone quality in the context of augmented glenoid components. The bone strain field was also compared when different augmented glenoid components underwent simulated joint loading using finite element analysis.

Asymmetrically eroded glenoids were found to have denser bone (p

Modeling Stokes Flow Using Hierarchical Structure-Preserving B-Splines, Kendrick Monroe Shepherd

Theses and Dissertations

A new spline space, the hierarchical structure-preserving B-spline space, is introduced and implemented in the analysis of Stokes flow. The space, when properly constrained, is shown to be stable and to have at least optimal convergence rates in the velocity field and suboptimal convergence rates in the pressure field. However, results show that superoptimal convergence can often be expected in the pressure field, likely due to error reduction in the velocity field. Like other hierarchical spline spaces, these splines are shown to greatly increase accuracy and to drastically lower computation times for analyses on domains whose solution fields have singularities …

On An Effective Submodeling Procedure For Stresses Determined With Finite Element Analysis, Ajay Ashok Kardak

LSU Doctoral Dissertations

Submodeling can enable stress analysts using finite elements to focus analysis on a subregion containing the stress concentration of interest, with consequent computational savings. Such benefits are only truly realized if the boundary conditions on the edges of the subregion that were originally contained within the global region are sufficiently accurate. These boundary conditions are drawn from initial global finite element analysis (FEA), and consequently themselves have errors that in turn lead to errors in the stresses sought. When these last boundary-condition errors are controlled, and the discretization errors incurred by the FEA of ensuing submodels are also controlled, submodeling …

Thermomechanical Stabilities In Automotive Brakes & Clutches Systems, Ali Bendawi

Electronic Theses and Dissertations

This thesis involves three related topics in the area of thermal stress resulting from sliding contact of frictional materials. These three contributions collectively and the discussion of them herein form a collective basis furthering the research and understanding within this field. Firstly, the effect of convective cooling on thermoelastic instability is evaluated using finite element analysis involving insertion of a thermal convection term in the formula for frictional heat generation. It has been found that convection or radiation heat dissipation can stabilize the thermal-mechanical feedback process, leading to a raised critical sliding velocity. Two representative models for brake and clutch …

Development, Testing, And Analytical Modeling Of Fiber-Reinforced Polymer Bridge Deck Panels, Hesham R. Tuwair

Doctoral Dissertations

A fiber-reinforced, polyurethane foam core was developed, tested, and evaluated as a possible replacement for the costly honeycomb core that is currently used to manufacture fiber-reinforced polymer (FRP) bridge deck panels. Replacing these panels would reduce both initial production costs and construction times while also enhancing structural performance. Experimental, numerical, and analytical investigations were each conducted. Three different polyurethane foam (PU) configurations were used for the inner core during the study’s first phase. These configurations consisted of a high-density PU foam (Type 1), a gridwork of thin, interconnecting, glass fiber/resin webs that formed a bidirectional gridwork in-filled with a low-density …