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Articles 1 - 8 of 8
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Three-Dimensional Lattices As Effective Impact Absorption Layers For Space Applications, James Youchison
Three-Dimensional Lattices As Effective Impact Absorption Layers For Space Applications, James Youchison
Mechanical Engineering ETDs
Additive manufacturing (AM) is increasingly becoming a viable manufacturing process due to dramatic advantages that it facilitates in the material selection and design complexity. This paper investigates the potential of additively manufactured lattice structures for the application of dissipating impact energy. In this research the role of geometry and material properties on the static and dynamic energy absorption properties of additively manufactured wave spring lattices composed of various materials were studied under drop/impact and compression tests. A finite element simulation of the lattice structure was also conducted, although the results were overall inconclusive, it gave some great insight into the …
Interaction Of A Shock Wave With A Particle Curtain, Daniel M. Freelong
Interaction Of A Shock Wave With A Particle Curtain, Daniel M. Freelong
Mechanical Engineering ETDs
This thesis presents an experimental study of the interaction of a normal shock wave with a sparse curtain of particles. Soda lime particles with a nominal diameter of 40 micrometers are used to form the curtain. A high speed camera captured several segments of the particle curtain flow from the front view, including the early formation stages. The frames from the video segments were then extracted into individual sequential images. Properties were found using the images such as the velocity fields, time evolution of multiphase Atwood number, and perturbation growth. Volume fractions were derived from mass discharge measurements and particle …
Dynamic Hvac Energy Management Using Commercial Building Occupancy Metrics & Neural Networks, Krishna Chaitanya Jagadeesh Simma
Dynamic Hvac Energy Management Using Commercial Building Occupancy Metrics & Neural Networks, Krishna Chaitanya Jagadeesh Simma
Civil Engineering ETDs
With the rise of technology use in buildings, it is now possible to collect data that can be used to improve building energy consumption. One factor that has significant impact on building energy consumption is occupancy. Recent studies have shown promising results in obtaining occupancy information from existing infrastructure such as WiFi router networks. However, these existing frameworks require additional investments through software upgrades, added infrastructure, computational resources, and may raise occupant privacy concerns. Additionally, with occupant thermal comfort statistics being lower than ASHAREA specified standards, a novel approach for indoor climate control is needed. To address the limitations in …
Airborne Counter-Uncrewed Systems With Runtime Assurance Control, Isaac J. Seslar
Airborne Counter-Uncrewed Systems With Runtime Assurance Control, Isaac J. Seslar
Mechanical Engineering ETDs
This thesis develops a response to the increase in the availability of the commercially available uncrewed aerial systems and is dedicated to the detection, classification, and tracking required to successfully neutralize when determined malicious. A requirement of actively avoiding obstacles using runtime assurance is addressed and designed to keep the hardware safe in potentially dangerous situations. This work will elaborate on the several components the test bed is comprised of, specifically the hardware and software portions that successfully solve the problem. The software encompasses the simulation, the multiple algorithms required for the tracking, and the machine learning required for detection …
A Practical Methodology To Detect, Quantify And Characterize Experimental Uncertainties In The Dynamic Testing Of Structures, James L. Woodall
A Practical Methodology To Detect, Quantify And Characterize Experimental Uncertainties In The Dynamic Testing Of Structures, James L. Woodall
Civil Engineering ETDs
This thesis investigates the uncertainty in the experimental context of structural dynamics. This thesis proposes a method to estimate both the effect of boundary conditions, as well as two different methods to detect the location of sensors on a specimen. Firstly, this thesis proposes a technique to predict the dynamic behavior of any point along a cantilever beam with an uncertain transverse elastic restraint. Secondly, this thesis investigates the estimation of the location of a sensor given the output data of a physical experiment with two different methods. Small errors in the sensor location may go unnoticed in the frequency …
Feasibility Study Of A Structural Electrolyte Containment Ring For Use In Thermal Batteries, Teal Harbour
Feasibility Study Of A Structural Electrolyte Containment Ring For Use In Thermal Batteries, Teal Harbour
Mechanical Engineering ETDs
The feasibility of a new thermal battery separator design utilizing a structural machined MACOR® ceramic is explored. The cylindrical ceramic “separator ring” maintains separation of cell electrodes while containing a LiCl-KCl molten salt electrolyte. Finite element analysis (FEA) results show the separator ring can withstand mechanical and thermal loading conditions representative of a thermal battery environment. Electrical Impedance Spectroscopy (EIS) was used to characterize impedance mechanisms. EIS data was also used to calculate and show conductivities of the experimental separators are comparable to a traditional pellet. Although discharge testing resulted in high current-pulse resistivities and low delivered capacity, the work …
Printing Parameter Determination And Characterization Of Additively Manufactured Kovar Steel, Will Macgreggor Davidson
Printing Parameter Determination And Characterization Of Additively Manufactured Kovar Steel, Will Macgreggor Davidson
Mechanical Engineering ETDs
Kovar (ASTM F15, UNS K94610) steel has many applications across Sandia National Laboratories but is best known within academia and industry for its glass-to-metal and glass-to-ceramic hermetic sealing capabilities. Successful printing parameters for a Renishaw AM400 to additively manufacture artifacts from Kovar steel powder have been determined. The printed test artifacts have been studied for ultimate tensile strength, density, surface roughness, hardness, bulk composition, and impact toughness. Longer throughput measurements such as porosity, coefficient of thermal expansion, and grain structure studies have been established for future delivery to the research team. Yet another delivery from this thesis research is a …
Fundamental Dislocation Solutions For Infinite And Semi-Infinite Media, Luo Li Mr
Fundamental Dislocation Solutions For Infinite And Semi-Infinite Media, Luo Li Mr
Mechanical Engineering ETDs
Much research has gone into determining stress fields of dislocation, as the understanding of dislocations is fundamental to understanding metal or crystal plasticity. In this thesis, the stress field of a rectangular dislocation loop in an infinite isotropic solid is developed for a Volterra-type dislocation with three non-zero Burgers vector components. Also, the stress and strain fields of a rectangular dislocation loop in an isotropic solid, which is a semi-infinite medium, are obtained here for a Volterra-type dislocation. Moreover, analytical and numerical verifications of the developed stress/strain fields are performed. This is done by ensuring the satisfaction of the equilibrium …