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Stability Of A Spinning Triangle Tethered Spacecraft System In A Circular Orbit, Matthew James Heitstuman Dec 2018

Stability Of A Spinning Triangle Tethered Spacecraft System In A Circular Orbit, Matthew James Heitstuman

Mechanical Engineering ETDs

Equations of motion are derived for a spinning triangle tethered spacecraft system and are used to analyze the stability of such systems. Floquet theory is applied to the linearized, periodic coefficient, equations of motion to analyze spin stability as a function of triangle geometry and the average spin rate of the satellite relative to the angular velocity of the spacecraft orbiting around a central body. The results of the Floquet analysis show that spin stability is achievable for many combinations of spacecraft geometry and spin rate. Spacecraft engineers or operators for a triangle-shaped tethered spacecraft can use this information for ...


Elevated Temperature Progressive Damage And Failure Of Duplex Stainless Steel, Darren P. Luke Dec 2018

Elevated Temperature Progressive Damage And Failure Of Duplex Stainless Steel, Darren P. Luke

Civil Engineering ETDs

Ductile failure of metals has been the focus of research efforts within academia and industry for many years since it is tremendously important for understanding the failure of structures under extreme loading conditions. However, limited research has been dedicated to elevated temperature ductile failure, which is critical for evaluating catastrophic events such as industrial, structural or shipping vessel fires. A detailed investigation was conducted on the structural response of Duplex Stainless Steel at elevated temperatures. The temperature dependence of elastic modulus, yield strength, ultimate strength, and ductility was measured up to 1000°C and a continuum damage plasticity model was ...


Integration Of A Commercial Smart Thermostat To The Aggregated Load Control Simulation Framework, Jee Won Choi Dec 2018

Integration Of A Commercial Smart Thermostat To The Aggregated Load Control Simulation Framework, Jee Won Choi

Mechanical Engineering ETDs

As part of an effort to achieve a better balance between the power demand and supply, load (demand) control simulation framework is previously developed. In the framework, HVAC load is used as a control resource, driven by the thermostat logic modeled within the framework. However, it has not been proved, whether a com- mercial thermostat is able to perform modeled thermostat’s features. Therefore, it is desired to integrate a commercial thermostat to the framework, to verify its capabil- ity of participating and performing the Demand Response (DR) scheme developed. A ‘Nest Learning Thermostat’ is selected as a commercial thermostat ...


Engineering Viscoelastic Behavior Of Carbon Fiber Reinforced Polymer Composites With Nanoparticles For Controlling Deployment Of Aerospace Structures, Mark Scherbarth Nov 2018

Engineering Viscoelastic Behavior Of Carbon Fiber Reinforced Polymer Composites With Nanoparticles For Controlling Deployment Of Aerospace Structures, Mark Scherbarth

Mechanical Engineering ETDs

The United States Air Force is focused on reducing mass and power consumption of spacecraft to increase their capabilities for space missions. Low mass and power consumption can be achieved by using composites with low density and high stiffness and utilizing few satellite components. One way to achieve reduced mass is by eliminating attendant deployment mechanisms consuming valuable power and mass allocations on spacecraft with deployable structures. Secondary systems are typically used to assist deployable space structures to ensure 100% success. A passively deployed space structure would be of great value to the Department of Defense and the commercial marketplace ...


Reducing Stress In 3d Printed Parts Made With Laser Engineered Net Shaping, Shaun Ross Whetten Apr 2018

Reducing Stress In 3d Printed Parts Made With Laser Engineered Net Shaping, Shaun Ross Whetten

Mechanical Engineering ETDs

Thermal cycling and repeated melting/solidification cycles characteristic of 3D metal printing processes causes buildup of residual stress in 3D printed parts. Using laser engineered net shaping (LENS®), residual stresses are formed leading to deformation and possible cracking of the 3D printed metal components. The LENS process offers opportunities for rapid prototyping, alternative manufacturing processes, and repair of worn/broken components so it is important to be able to minimize the effects of residual stress. Work was performed to understand the benefit of substrate heating on reducing residual stress in metal parts made using the LENS process. Substrate deformation, and ...


Fatigue Crack Modeling Of Additively Manufactured Abs Cantilever Beam, Jason W. Booher Apr 2018

Fatigue Crack Modeling Of Additively Manufactured Abs Cantilever Beam, Jason W. Booher

Mechanical Engineering ETDs

A Finite Element model was developed to model crack development in additively manufactured additively manufactured Acrylonitrile Butadiene Styrene (ABS) cantilever beams. Experiments were conducted on the beams with both shock and random vibration base excitations. The base excitations induced damage in the beam that cause crack propagation. It was observed during the cracks developmental stages that an increase in damping occurred. The proposed Finite Element model also showed similar increases in damping from the addition of Coulomb damping forces.