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Two Dimensional Friction Stir Welding Model With Experimental Validation, Charles Blake Owen Mar 2006

Two Dimensional Friction Stir Welding Model With Experimental Validation, Charles Blake Owen

Theses and Dissertations

The performance of a coupled viscoplastic model of FSW has been evaluated over a variety of tool RPMs and feed rates. Initial results suggested that further optimization of the material parameters and an additional ability to model the thermal recovery of the material would improve the overall performance of the model. Therefore, an experimental/numeric approach was taken to improve and quantitatively compare the performance of the model based upon the thermal profile of the workpiece. First, an experimental method for obtaining real-time temperature measurements during Friction Stir Processing (FSP) of 304L Stainless Steel was developed. The focus of the ...


A Multiscale Model For Dilute Turbulent Gas-Particle Flows Based On The Equilibration Of Energy Concept, Ying Xu, Shankar Subramaniam Jan 2006

A Multiscale Model For Dilute Turbulent Gas-Particle Flows Based On The Equilibration Of Energy Concept, Ying Xu, Shankar Subramaniam

Mechanical Engineering Publications

The objective of this study is to improve Eulerian-Eulerian models of particle-laden turbulent flow. We begin by understanding the behavior of two existing models—one proposed by Simonin [von Kármán Institute of Fluid Dynamics Lecture Series, 1996], and the other by Ahmadi [Int. J. Multiphase Flow16, 323 (1990)]—in the limiting case of statistically homogeneous particle-laden turbulent flow. The decay of particle-phase and fluid-phase turbulent kinetic energy (TKE) is compared with direct numerical simulation results. Even this simple flow poses a significant challenge to current models, which have difficulty reproducing important physical phenomena such as the variation of turbulent kinetic ...


Mesoscale Predictions For The Dynamic Compaction Of Explosively-Coated Aluminum Micro-Particles, Michael Wayne Crochet Jan 2006

Mesoscale Predictions For The Dynamic Compaction Of Explosively-Coated Aluminum Micro-Particles, Michael Wayne Crochet

LSU Master's Theses

Conventional granular explosives are widely used in aerospace and defense-related industries. Powdered metals are often mixed with high explosives to enhance detonation. The effectiveness of these mixtures is limited by the slow burning of the metal relative to the explosive and their sensitivity to mechanical loading. Granular energetic composites, composed of an aluminum core coated with a layer of the high explosive RDX (C3H6N6O6), may be a high-performance alternative to conventional explosives because of a higher metal combustion rate and lower impact sensitivity. Though the technology required to manufacture granular energetic composites exists ...