Mechanical and Aerospace Engineering electronic theses and dissertations (MU)
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The items in this collection are the theses and dissertations written by students of the Department of Mechanical and Aerospace Engineering. Some items may be viewed only by members of the University of Missouri System and/or University of Missouri-Columbia. Click on one of the browse buttons above for a complete listing of the works.
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Item The fracture resistance of experimental alloy and Class U carbon steel wrought railroad wheels(University of Missouri--Columbia, 1986) Roland, John Russel; Bowles, C. QuintonMechanical and metallographic testing was used to relate fracture toughness to the mechanical properties and the metallurgical characteristics of Class U carbon steel wrought wheels and an experimental alloy wrought wheel. The study was performed to determine how variations in carbon content and alloy addition influenced these relationships. The results of the research suggest the chromium addition found in the experimental alloy and the variation in prior austenite grain size had little effect on toughness. Carbon content reduction and the resulting amount of proeutectoid ferrite in the microstructure were found to be the principal factors controlling fracture toughness of the wrought steel wheels.Item Applications of the hemi-cube radiosity method(University of Missouri--Columbia, 1988) Jensen, Eric Dean; Sandgren, Eric"Computer generated pictures have evolved from crude, 'wire frame' drawings to images of near photograph guality. Advancements in hardware and software technology have enabled engineers to produce nearly lifelike synthetic images by accurately representing shaded surfaces, shadows, reflections, etc. This thesis studies one of the most recently developed and technically advanced shading algorithms. The accuracy of the model is tested by three independent methods, and applications of this algorithm as a general radiant energy modeling technique for problems other than synthetic imaging are investigated."--Preface.Item CGSOPT : a computer graphics pre- and post- processor for structural optimization(University of Missouri--Columbia, 1987) Chen, Hung-Pin; Sandgren, EricCGSOPT is a computer graphics program designed to be used as an aid in providing a graphical environment for the designer to keep track of the progress of the structural optimization procedure. The three dimensional geometry, node coordinates, element types, node and element labels, material properties, boundary constraints, and loading conditions for a truss or frame structure can be viewed and manipulated at the computer graphics workstation. This aids in verification of the input data required for the analysis processor. The output data from the analysis processor, such as stress and deformation, corresponding to the design variable selection in the optimization process can also be displayed at the console to document the path taken by the structural optimization process.Item Finite element analysis of periodic shells and origami tessellations(University of Missouri--Columbia, 2024) Weber, Andrew; Nassar, Hussein[EMBARGOED UNTIL 12/01/2025] A numerical solver was designed to determine the effective material properties of smooth and rigid crease origamis. The solver was created using Ansys APDL and Workbench and utilized periodic boundary conditions for efficient unit cell-based simulations. Three origami tessellations were simulated by the solver: the Smooth "Eggbox, Rigid "Eggbox", and "Cosine Zigzag" patterns. The solver calculated in-plane and out-of-plane Poisson's ratios for each tessellation, matching up with previously observed or theoretical values with a low relative error. Cavities were imposed onto the three tessellation patterns to investigate the effect it had on the resulting material properties. The Cosine "Eggbox" pattern was found to maintain Poisson's ratio after introduction of cavities. The Rigid "Eggbox" pattern maintained its in-plane Poisson's, but further analysis of the out-of- plane properties is needed. The "Cosine Zigzag" pattern did not demonstrate any similarity in material properties before and after introducing cavities. The study highlights the need for further investigation in this subject as well as the effectiveness of the numerical solver.Item Examination of aluminum nano/micro particle behavior via photothermal heating(University of Missouri--Columbia, 2024) Tauer, Conrad Pierce; Maschmann, Matthew[EMBARGOED UNTIL 12/01/2025] Aluminum's high energy density, natural abundance, and unique reactivity make it a critical material for energetic applications in explosives, propellants, and pyrotechnics. The following thesis explores the photothermal behavior and reaction mechanisms of aluminum nano/micro particles under laser irradiation. Experimentation focuses on supporting the melt dispersion mechanism as the primary reaction driving spallation rather than the diffusive oxidation mechanism. Experiments were conducted in both inert argon environments and ambient air to isolate the role of oxygen in particle behavior. A scanning electron microscope and custom optical microscope allowed for precise imaging and targeting of particles. The results reveal that spallation is primarily driven by a thermomechanical mechanism. The work herein reports inert testing of aluminum nanoparticles in an argon atmosphere without nearby oxidizers, confirming that oxygen is not necessary for MDM-driven spallation. Also, the findings provide new insights into the fundamental thermal responses of aluminum micro particles under varying parametrics of laser irradiation.