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The study investigates the behavior open cell aluminum foam in scenarios applicable to potential use in structural applications. Behavior was examined through mechanical testing, computer modeling and analytic expressions. Existing assumptions about the foam characteristics that define the elastic properties were expanded to include contributions of axial and shear deformations in addition to bending and were rewritten in terms of the axial and bending stiffness ratios of ligaments. Compressive and tensile tests were performed to gain a measure of the elastic properties of the foam as well as the behavior and failure mechanisms in both loading conditions. The materials used in testing were manufactured and supplied by ERG Duocel with defined porosities of 20 and 40 ppi and relative density of 6-8%. Fatigue tests were performed on open cell foam samples to determine the strain to fatigue life relationship for the material at high applied strain amplitudes. Finally, finite element models were created in ADINA for both ordered and random networks. The changes in elastic properties due to relative density, defined by ligament geometry, cell anisotropy and joint connectivity were measured for ordered networks, while irregular, random networks were used to investigate the forces developed within ligaments. Conclusions from this study provide insight on the behavior of open cell foam and promote further research in an effort to determine the viability of structural use of the material.

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The current uses of unmanned aerial vehicles (UAVs) in wildland firefighting center around mapping, scouting, and firing operations. These operations and additional operations are often held back by lack of range and lift capacity of current UAV options. Software design tools were developed in this research to aid in designing a UAV for wildland firefighting. The tools help create a mission profile, estimate the mass of the UAV, select a motor and rotor, select a battery, and generate and analyze a finite element (FE) sector model. These tools leverage parametric analysis and studying existing hardware to create a design. The FE model is generated based on the mission profile, a motor and rotor, and battery as design parameters and a set of design variables. The tools developed for creating a mission profile, estimating mass, selecting a motor and rotor, and selecting a battery successfully aid the preliminary design of an octocopter, hexacopter, and quadcopter. The FE tool was designed around an octocopter's geometry, which leads to complications in generating FE models for a hexacopter or quadcopter. Recommendations were made for altering the FE tool to account for hexacopters and quadcopters. Other recommendations were made to support future work in creating an optimized design of a wildland firefighting UAV. / Master of Science / The use of multirotor UAVs in various industries is rapidly expanding. One industry that currently uses UAVs but is limited in their capabilities is wildland firefighting. Wildland firefighters use UAVs for scouting, mapping, and firing operations. Scouting includes finding road access to the fire, finding water sources, searching for spot fires, and many other applications. Mapping is typically done to understand the size of the fire. Firing operations are conducted to start small, controlled fires to remove fuel from the fires path. However, these operations as well as future applications of UAVs are often limited by the flight time and the lifting capabilities current UAV options offer. Tools were developed in this research to create a preliminary design of a UAV for wildland firefighting. The design parameters and variables of the UAV design are outlined throughout the tools. The tools allow for compiling mission requirements, selecting motors/rotors and a battery to use in the UAV, and a preliminary structural analysis of the UAV design. The preliminary structural analysis includes extracting stresses, strains, and displacements experienced through a simplified mission as well as the natural frequencies of the finite element sector model. The design of octocopters, hexacopters, and quadcopters were explored using the set of design tools. The tools were successfully in selecting components for each style of UAV and at the preliminary structural analysis of the octocopter design. However, the structural analysis was not able to be conducted for the hexacopter and quadcopter design due to geometric conditions in the finite element model.

Hybrid organic-inorganic nanocomposites have received considerable attention during the last five years due to their unexpected properties. This work incorporated nanodispersed organically modified montmorillonite clay into polydicyclopentadiene resin matrices. Montmorillonite consists of 1 nm platelet sheets with a 2:1 structure, consisting of an alumina octahedral layer sandwiched between two silica tetrahedral layers. The relative weak forces between platelets allow small molecules like water, solvents and monomers as well as polymers, to enter into the interlayer spacings between the platelet sheets. In-situ polymerization of highly delaminated clay/dicyclopentadiene(DCPD) dispersions was used to prepare clay/polydicyclopentadiene (polyDCPD) nanocomposites. Highly delaminated composites were characterized using X-ray diffraction, X-ray scattering and high resolution TEM. Composites with 0.5-1 weight percent of clay had higher Tg values and flexural moduli. The flow properties of the organically-modified montmorillonite/DCPD liquid dispersions were examined using a co-rotating viscometer. The dispersions with clay concentrations higher than 0.5wt% clay in DCPD showed thixotropic flow behavior. Small angle neutron scattering (SANS) experiments were performed to obtain anisotropic scattering of highly delaminated clay in DCPD due to the orientation of clay platelets and tactoids in the shear field. No anisotropic scattering was observed. The reason for this unexpected result is not yet understood. Highly delaminated organically-modified clay composites were examined using small angle neutron scattering (SANS) and ultra small angle neutron scattering (USANS). The SANS data from 0.5, 1 and 2wt% clay/polyDCPD composites with 2 different types of clay were fitted to the stacked disk model. The average number of clay layers per tactoid was predicted by fitting the experimental data to the stacked disk model. Extensive high-resolution TEM analyses were performed on the same samples to obtain the average numbers of clay layers per tactoid. Two finite element models, one for the intercalated clay/polyDCPD nanocomposite and one for the exfoliated clay/polyDCPD nanocomposite, were developed. The effects of these different dispersion geometries for seven platelets in the polyDCPD matrix on the stress distributions were examined. The exfoliated platelet model showed reduced deformations and uniform stress distributions. The highest stress concentrations were found on the platelets? surfaces and where platelets were in close proximity.

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Anthropogenic sound in Florida's waters and coastal waterways is most commonly caused by overwater development, marine traffic, and military activity. Overwater construction has increased over the years as a result of aging infrastructure and rising expansions around the United States, including more than forty US Naval facilities containing tens of thousands of feet of pier. Construction methodology, such as pile driving, has risen in shallow waters to build structures such as bridges, piers, and wind farms, with significant consequences for marine life and the environment. More precisely, pile driving activities generate significant decibel levels in the surrounding marine environment. Measurements taken from hydrophones placed in the water near the construction site indicate that the high sound pressure levels produced may be harmful to marine life and the environment. As a result, standards have been established to help alleviate and decrease the possible harm that high decibel sound levels may produce. However, these additional steps increase the overall cost of the construction project. This thesis focuses on replicating the pile driving process using finite element modeling to hydroacoustic parametric study of pile driving-induced anthropogenic sound in neighboring Florida seas, as well as the possible environmental impact of the state's numerous naval base piers. The modeling predictions can then be used to identify the distance from the pile at which marine life and the environment are no longer adversely affected. In addition, computer modeling can reduce construction costs when compared to on-site sensors and monitoring. / Master of Science / Over recent years there has been an increase in the amount of manmade noise in Florida and its coastal waterways due to overwater construction, marine traffic, and military activities. Pile driving construction has increased in shallow waters to build infrastructure, which includes bridges, piers, and wind farms, resulting in a negative impact for marine life and the environment. Federal agencies have established guidelines to ease the harmful effects construction has on marine life and the environment. However, there is concern that these recent guidelines may not properly consider all the geometric and hydrographic variables of manmade noise that affect the high sound exposure levels during pile driving. With a more accurate understanding of the sound generation produced from pile driving, predictions can assist with sound mitigation to ensure less harm to the marine life and environment. In turn, construction companies and government agencies informed with this enhanced understanding can make better decisions that lead to fewer (or possibly eliminate) transmission loss discrepancies and costly noise mitigation measures. Consideration of the marine environment is one of the United States Navy's top priorities with naval stations located throughout the State of Florida that possess thousands of feet of waterfront structures, including piers, requiring routine maintenance and construction. This thesis models the pile driving process through finite element modeling in COMSOL Multiphysics computer software, testing the various parameters that Florida waters may encounter with pile driving on the surrounding coast as well as naval bases.