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The Effect Of Porosity On The Fatigue Life Of 8630 Cast Steel, Paul T Deegan Jan 2006

The Effect Of Porosity On The Fatigue Life Of 8630 Cast Steel, Paul T Deegan

Theses and Dissertations

The fatigue life of 8630 cast steel is studied by employing axial testing. The cast steel specimens are designed with varying levels of porosity and are verified using radiography and microscopy. A qualitative correlation can be made about the fatigue life to the amount/size of porosity that exists in cast steels based on the results.


An Adaptively Refined Cartesian Grid Method For Moving Boundary Problems Applied To Biomedical Systems, Sreedevi Krishnan Jan 2006

An Adaptively Refined Cartesian Grid Method For Moving Boundary Problems Applied To Biomedical Systems, Sreedevi Krishnan

Theses and Dissertations

A major drawback in the operation of mechanical heart valve prostheses is thrombus formation in the near valve region potentially due to the high shear stresses present in the leakage jet flows through small gaps between leaflets and the valve housing. Detailed flow analysis in this region during the valve closure phase is of interest in understanding the relationship between shear stress and platelet activation.

An efficient Cartesian grid method is developed for the simulation of incompressible flows around stationary and moving three-dimensional immersed solid bodies as well as fluid-fluid interfaces. The embedded boundaries are represented using Levelsets and treated ...


A Univariate Decomposition Method For Higher-Order Reliability Analysis And Design Optimization, Dong Wei Jan 2006

A Univariate Decomposition Method For Higher-Order Reliability Analysis And Design Optimization, Dong Wei

Theses and Dissertations

The objective of this research is to develop new stochastic methods based on most probable points (MPPs) for general reliability analysis and reliability-based design optimization of complex engineering systems. The current efforts involves: (1) univariate method with simulation for reliability analysis; (2) univariate method with numerical integration for reliability analysis; (3) multi-point univariate for reliability analysis involving multiple MPPs; and (4) univariate method for design sensitivity analysis and reliability-based design optimization.

Two MPP-based univariate decomposition methods were developed for component reliability analysis with highly nonlinear performance functions. Both methods involve novel function decomposition at MPP that facilitates higher-order univariate approximations ...


Stability Analysis Of Atomic Structures, Liang Zhang Jan 2006

Stability Analysis Of Atomic Structures, Liang Zhang

Theses and Dissertations

The stability and failure mechanism of a structure at the nanometer scale are important for understanding the mechanical behavior of nanoscale materials and structures. This thesis focuses on the material stability of atomic structures. First, the material stability of pristine carbon nanotubes is investigated at the continuum level by using the crystal elasticity theory. A homogenized continuum model is adopted. The strong ellipticity condition is employed to capture the localized failure of carbon nanotubes. The critical strain and strength predicted are reasonably comparable with experimental estimations.

An atomic material stability theory is developed as the atomistic counterpart of the continuum ...


Wheel Loader Powertrain Modeling For Real-Time Vehicle Dynamic Simulation, Matthew Michael Tinker Jan 2006

Wheel Loader Powertrain Modeling For Real-Time Vehicle Dynamic Simulation, Matthew Michael Tinker

Theses and Dissertations

No abstract provided.


A Parallelized Sharp-Interface Fixed Grid Method For Moving Boundary Problems, Saikrishna V Marella Jan 2006

A Parallelized Sharp-Interface Fixed Grid Method For Moving Boundary Problems, Saikrishna V Marella

Theses and Dissertations

The primary objective of this thesis is to develop a general computational framework to perform large scale moving boundary problems in fluid mechanics. The interactions of moving entities with fluid flow are common to numerous engineering and biomedical applications. The novel computational platform developed comprises of a) an efficient fluid flow solver b) an accurate and easily implemented unified formulation to capture the interactions of the moving bodies with the flow and c) parallel execution capability to enable large scale computations. The above features are formulated and implemented in a computer code, ELAFINT3D. The current thesis demonstrates the accuracy, efficiency ...