Space missions design requires already tested and trusted control algorithms for spacecraft motion. Rapidly testing control algorithms at a low cost is essential. A novel robotic system that emulates orbital motion in a laboratory environment is presented. The system is composed of a six degree of freedom robotic manipulator fixed on top of an omnidirectional ground vehicle accompanied with onboard computer and sensors. The integrated mobile manipulator is used as a testbed to emulate and realize orbital motion and control algorithms. The kinematic relations of the ground vehicle, robotic manipulator and the coupled kinematics are derived. The system is used to emulate an orbit trajectory. The system is scalable and capable of emulating servicing missions, satellite rendezvous and chaser follower problems.

This research addresses various models of a spring-mass system that uses a spring made of a shape memory alloy (SMA). The system model describes the martensite fractions, which are values that describe an SMA's crystalline phases, via differential equations. The model admits and this thesis contrasts two commonly used but distinct assumptions: a homogeneous case where the martensite fractions are constant throughout the spring's cross section, and a bilinear case where the evolution of the martensite fractions only occurs beyond some critical radius. While previous literature has developed a model of the system dynamics under the homogeneous assumption using the martensite-fractions differential equations, little research has focused on the dynamics when considering the bilinear case, especially using the differential equations. This thesis models the system dynamics under both the homogeneous and bilinear assumptions and determines if the bilinear case is an improvement over the homogeneous case. The research develops a numerical approach of the system dynamics for both martensite-fractions assumptions. For various initial displacements and temperatures, plotting the resulting displacement, velocity, and martensite fractions over time determines the coherence of the assumptions. Not only did the bilinear assumption offer more reasonable plots, but the homogeneous assumption delivered bizarre results for certain temperatures and initial displacements. For future research, a fully nonlinear case can replace the homogeneous and bilinear assumptions. Additionally, future research can utilize other martensite-fractions evolution models, as opposed to differential equations.

With the increasing data handling and power requirements of today's spacecraft, accurately modeling the effects of cabling on spacecraft structural dynamics has become an increasingly important part of the design process. During testing, spacecraft cabling produces a damping effect on the system dynamics; however, current models often overpredict this response in higher frequency modes and produce unrealistic damping values. Previous models incorporated structural and viscous damping terms into Euler-Bernoulli and shear beams; this thesis presents a viscous damping model for Timoshenko beams that can accurately capture the effects of both spacecraft wiring and harnesses during the design phase. Damping in built-up structures shows a weak frequency-dependence; therefore, it is of interest to develop a combination of damping terms and coefficients that provide approximately frequency-independent modal damping. Where previous work included a rotation-based damping term to Euler-Bernoulli beam equations to produce frequency-independent damping, this thesis includes higher-order derivative damping terms to characterize their motion. Because Timoshenko beams account for the effects of both transverse shear and rotary inertia, it is of interest to characterize the damping coefficients using these parameters. Finally, deformed beam shapes were studied to further characterize each damping term as a physical dissipative mechanism.

Carbon fiber composites have become popular in aerospace structures and applications due to their light weight, high strength, and high performance. Hybrid carbon fiber reinforced polymer (HCFRP) composites with alumina nanoparticles reinforcement display improved material properties such as fracture toughness, resistance to crack propagation and improved fatigue life. However, homogeneous dispersion of nanoscale materials in the matrix is important for even distribution of the improved properties. Implementing silane coupling agents (SCAs) improves dispersion by acting as a bridge between organic and inorganic materials, which increases interfacial strength and decreases sedimentation by bonding the particulate filler to the fiber reinforcement. This research is aimed at quantifying the improvement in dispersion of nanoparticles and elucidating the effects on the mechanical property of HCFRP samples through the novel use of photoluminescent characteristic peaks emitted by the alumina reinforcement particles. Photo-luminescene emission from secondary reinforcement particles of alumina embedded within the hybrid carbon fiber composites is leveraged to reveal microstructural effects of functionalization and particle weight fraction as it relates to overall composite mechanics. 6, 9 and 12 weight percentage of alumina particle loading with Reactive Silane Coupling Agents, Non-reactive Silane Coupling Agent surface treatments and untreated condition are investigated in this research. Uniaxial tensile tests were conducted with measurements using piezospectroscopy (PS) and concurrent digital image correlation (DIC) to quantify the mechanical property and load distribution between the carbon fiber/epoxy and the reinforcing nanoparticles. The piezospectroscopic data were collected in an in-situ configuration using a portable piezospectroscopy system while the sample was under tensile load. Photoluminescence results show the dispersion and sedimentation behavior of the nanoparticles in the material for different surface treatment and weight percentage of the alumina nanoparticles. The piezospectroscopic maps capture and track the residual stress and its change under applied load. The results reveal the effect of varying particle loading on composite mechanical properties and how this changes with different functionalization conditions. The role of the particles in load transfer in the hybrid composite is further investigated and compared with theory. This work extends the capability of spectroscopy as an effective non-invasive method to study, at the microstructural level, the material and manufacturing effects on the development of advanced composites for applications in aerospace structures and beyond.

Extreme operating temperatures within the turbine section of jet engines require sophisticated methods of cooling and material protection. Thermal barrier coatings (TBCs) achieve this through a ceramic coating applied to a substrate material (nickel-based superalloy). Electron-beam physical vapor deposition (EB-PVD) is the industry standard coating used on jet engines. By tailoring the microstructure of an emerging deposition method, Plasma-spray physical vapor deposition (PS-PVD), similar microstructures to that of EB-PVD coatings can be fabricated, allowing the benefits of strain tolerance to be obtained while improving coating deposition times. This work investigates the strain through depth of uncycled and cycled samples using these coating techniques with synchrotron X-ray diffraction (XRD). In the TGO, room temperature XRD measurements indicated samples of both deposition methods showed similar in-plane compressive stresses after 300 and 600 thermal cycles. In-situ XRD measurements indicated similar high-temperature in-plane and out-of-plane stress in the TGO and no spallation after 600 thermal cycles for both coatings. Tensile in-plane residual stresses were found in the YSZ uncycled PS-PVD samples, similar to APS coatings. PS-PVD samples showed in most cases, higher compressive residual in-plane stress at the YSZ/TGO interface. These results provide valuable insight for optimizing the PS-PVD processing parameters to obtain strain compliance similar to that of EB-PVD. Additionally, external cooling methods used for thermal management in jet engine turbines were investigated. In this work, an additively manufactured lattice structure providing transpiration cooling holes is designed and residual strains are measured within an AM transpiration cooling sample using XRD. Strains within the lattice structure were found to have greater variation than that of the AM solid wall. These results provide valuable insight into the viability of implementing an AM lattice structure in turbine blades for the use of transpiration cooling.

Using quadcopters for analysis of an environment has been an intriguing subject of study recently. The purpose of this work is to develop a fully autonomous UAV platform for Railroad inspection The dynamics of the quadrotor is derived using Euler's and Newton's laws and then linearized around the hover position. A PID controller is designed to control the states of the quadrotor in a manner to effectively follow a vision-based path, using the down facing camera on a Parrot Mambo quadrotor. Using computer vision the distance from the position of the quadrotor to the position of the center of the path was found. Using the yaw controller to minimize this distance was found to be an adequate method of vision-based path following, by keeping the area of interest in the field of view of the camera. The downfacing camera is also simultaneously observing the path to detect defects using machine learning. This technique was able to detect simulated defects on the path with around 90% accuracy.

As populations and the demand for higher crop yields grow, so to does the need for efficient agricultural wheeled mobile robots. To achieve precise navigation through a field it is desirable that the control system is designed based on an accurate dynamic model. In this paper a control affine model for a custom designed skid-steer differential drive wheeled mobile robot is found. The Terramechanic wheel terrain interaction is adopted and modified to consider wheels with a torus geometry. Varying slip ratios and slip angles are considered in the terrain reaction forces, which is curve-fitted using a nonlinear least squares approach such that the achieved model is control affine. The parameters in the proposed model is identified through an extended Kalman filter so that the state variables in the model are matched. Both simulation and experiments in a commercial farm validated the proposed model and the identification approach.

The long duration airborne feature of airships makes them an attractive solution for many military and civil applications such as long-endurance surveillance, reconnaissance, environment monitoring, communication utilities, and energy harvesting. To achieve a minimum energy periodic motion in the air, an optimal trajectory problem is solved using basic direct collocation methods. In the direct approach, the optimal control problem is converted into a nonlinear programming (NLP). Pseudo-inverse and several discretization methods such as Trapezoidal and Hermite-Simpson are used to obtain a numerical approximated solution by discretizing the states and controls into a set of equal nodes. These nodes are approximated by a cubic polynomial function which makes it easier for the optimization to converge while ensuring the problem constraints and the equations of motion are satisfied at the collocation points for a defined trajectory. In this study, direct collocation method provides the ability to obtain an approximation solution of the minimum energy expenditure of a very complex dynamic problem using Matlab fmincon optimization algorithm without using Himiltonian function with Lagrange multipliers. The minimal energy trajectory of the airship is discussed and results are presented.

This thesis focuses on the development a streamlined process used to create novel meso-scale pattern used to induce negative Poisson's ratio (NPR) behavior at the bulk scale. This process includes, the development, optimization, and implementation of a candidate pattern. Currently, the majority of NPR structures are too porous to be utilized in conventional applications. For others, manufacturing methods have yet to realize the meso-scale pattern. Consequently, new NPR meta-materials must be developed in order to confer transformative thermomechanical responses to structures where transverse expansion is more desirable than contraction. For example, materials at high temperature. Additionally, patterns that take into account manufacturing limitations, while maintaining the properties characteristically attached to negative Poisson's Ratio materials, are ideal in order to utilize the potential of NPR structures. A novel NPR pattern is developed, numerically analyzed, and optimized via design of experiments. The parameters of the meso-structure are varied, and the bulk response is studied using finite element analysis (FEA). The candidate material for the study is Medium-Density Fiberboard (MDF). This material is relevant to a variety of applications where multiaxial stresses, particularly compressive, lead to mechanical fatigue. Samples are fabricated through a laser cutting process, and a comparison is drawn through the use of experimental means, including traditional tensile loading tests and digital image correlation (DIC). Various attributes of the elasto-plasticity responses of the bulk structure are used as objectives to guide the optimization process.

Recently, novel experimental evidence of continuous rotating detonations for gaseous H2/O2 propellants with a rotating detonation rocket engine (RDRE) was attained on the 3-inch Air Force Research Laboratory (AFRL) Distribution A RDRE, with the fuel and oxidizer injectors modified for H2/O2 gas propellants. Evident in previous experiments, detonation instabilities arising from upstream deflagration, from recirculation zones, and from insufficient gas mixing challenged resolution of detonation wave behavior from back-end imaging with the available optical equipment. Images were often over-illuminated from both the high amount of deflagration in the plume and the higher density of detonation waves in the annulus coupled with the small detonation cell size for H2/O2 gas propellants. Additionally, conventional optical systems attenuate the ultraviolet (UV) emission range (~308-320 nm wavelength) from the primary combustion species. To overcome these challenges are two methodologies that still utilize optical back-end imaging: (1) CH* chemiluminescence with fuel doping, and (2) OH* chemiluminescence. The first methodology utilizes doping CH4 into the H2/O2 gas mixture at a relatively small concentration of up to 5% by total mass flow rate to leverage CH* chemiluminescence at 409 ± 32 nm wavelength. The second methodology utilizes the combination of an OH* bypass filter for 308–320 nm wavelength to filter other emissions and an intensifier to amplify the detonation wave OH* emission. As of the present research, the first methodology was investigated across a regime of operating conditions, with planned future testing outlined to facilitate comparable data acquisition utilizing the second methodology.