Thesis (M.S.)--Mississippi State University. Department of Mechanical Engineering. / Title from title screen. Includes bibliographical references.

A general multidisciplinary design problem features coupling and feedback between contributing analyses. This feedback may lead to convergence issues requiring significant iteration in order to obtain a feasible design. This work casts the multidisciplinary design problem as a dynamical system in order to leverage the benefits of dynamical systems theory in a new domain. Three areas from dynamical system theory are chosen for investigation: stability analysis, optimal control, and estimation theory. Stability analysis is used to investigate the existence of a solution to the design problem and how that solution can be found. Optimal control techniques allow consideration of contributing analysis output and design variables constraints at the same level of the optimization hierarchy. Finally, estimation methods are employed to rapidly evaluate the robustness of the multidisciplinary design. These three dynamical system techniques are then combined in a methodology for the rapid robust design of linear multidisciplinary systems. While inherently linear, the developed robust design methodology is shown to be extensible to nonlinear systems. The applicability and performance of the developed technique is demonstrated through linear and nonlinear test problems including the design of a hypersonic aerodynamic surface for a system in which an increase in range or improvement in landed accuracy is sought. In addition, it is shown that the developed robust design methodology scales well compared to other methods.

La variété des concepts d'aéronef à voilure tournante n'a d'égal que l'étendue de leur hamp applicatif. Dès lors, se pose une question essentielle : quel concept est le plus adapté face à un certain nombre de missions ou de spécifications ? Une partie essentielle de la réponse réside dans l'étude des performances de vol et des impacts environnementaux de l'appareil. Le projet de recherche fédérateur C.R.E.A.T.I.O.N. pour " Concepts of Rotorcraft Enhanced Assessment Through Integrated Optimization Network " a pour but de mettre en place une plateforme numérique de calculs multidisciplinaires et multiniveaux capables d'évaluer de tels critères. La multidisciplinarité fait écho aux différentes disciplines associées à l'évaluation des giravions tandis que l'aspect multi-niveaux reflète la possibilité d'étudier un concept quelque soit l'état des connaissances sur ce dernier. La thèse s'inscrit dans ce projet. Une première implication est le développement de modèles de performances de vol et leur intégration dans des boucles de calcul multidisciplinaires. Au-delà de cet aspect de modélisation physique, la multidisciplinarité touche aussi le champ des mathématiques appliquées. Les méthodes d'optimisation multi objectifs multi paramètres, l'aide à la décision pour la sélection d'un optimum de meilleur compromis, l'exploration de bases de données, la création de modèles réduits sont autant de thématiques explorées dans cette thèse.

Mechatronic systems encompass a wide range of disciplines, including mechanical and electrical engineering, and hence the development process for mechatronic system is collaborative in nature. Currently the collaborative development of mechatronic systems is inefficient and error-prone because contemporary design environments do not allow sufficient information flow of design and manufacturing data across different engineering domains. Mechatronic systems need to be designed in an integrated fashion allowing designers from multiple engineering domains to receive updates regarding design modifications throughout the design process. One approach to facilitate integrated design of mechatronic systems is to integrate mechanical with electrical engineering CAD systems. Currently there exist numerous techniques that were developed to support various levels of integration between CAD/CAE systems. Standardized data exchange formats, e.g., STEP and IGES, support information exchange between various different CAD and PDM systems. Multi-Representation Architecture (Peak et al.) supports the integration of geometric information in CAD tools with analysis information in CAE tools. Other integration techniques include the Core Product Model (developed at NIST), Active Semantic Networks (Roller et al.), Constraint Linking Bridge (Kleiner et al.), and others. All these techniques have their areas of focus as well as research gaps that need to be covered. One area that needs research attention is the information exchange between mechanical and electrical domains, which is the focus of this thesis. In this thesis, the information exchange between mechanical and electrical domains is explored from two perspectives: conceptual design perspective, in which constraint relationship between attributes of mechanical and electrical components is identified and classified based on the physical forms, functions, and behavior of the mechatronic system; system realization perspective, in which the identified constraints are modeled for propagation between MCAD and ECAD systems. SysML is used to model the constraints between mechanical and electrical components. By means of an illustrative example (a robot arm), the constraint modeling and propagation developed in my thesis are demonstrated and implemented utilizing a MCAD system (SolidWorks) and an ECAD system (EPLAN Electric P8).

The concept of human-powered vertical flight was studied in great depth. Through the manipulation of preexisting theory and analytical methods, a collection of design tools was created to expediently conceptualize and then analyze virtually any rotor. The tools were then arranged as part of a complete helicopter rotor design process. The lessons learned as a result of studying this process—and the tools of which it consists—are presented in the following discussion. It is the belief of the author that by utilizing these tools, as well as the suggestions that accompany them, future engineers may someday build a human-powered helicopter capable of winning the Sikorsky Prize.

This thesis presents the work of two significant projects. In the first project, a suite of benchmark problems for grid energy management are presented which demonstrate several issues characteristic to the dynamic optimization of these systems. These benchmark problems include load following, cogeneration, tri-generation, and energy storage, and each one assumes perfect foresight of the entire time horizon. The Gekko Python package for dynamic optimization is introduced and two different solution methods are discussed and applied to solving these benchmarks. The simultaneous solve mode out-performs the sequential solve mode in each benchmark problem across a wide range of time horizons with increasing resolution, demonstrating the ability of the simultaneous mode to handle many degrees of freedom across a range of problems of increasing difficulty. In the second project, combined optimization of propulsion system design, flight trajectory planning and battery mass optimization is applied to solar-regenerative high-altitude long-endurance (SR-HALE) aircraft through a sequential iterative approach. This combined optimization approach yields an increase of 20.2% in the end-of-day energy available on the winter solstice at 35°N latitude, resulting in an increase in flight time of 2.36 hours. The optimized flight path is obtained by using nonlinear model predictive control to solve flight and energy system dynamics over a 24 hour period with a 15 second time resolution. The optimization objective is to maximize the total energy in the system while flying a station-keeping mission, staying within a 3 km radius and above 60,000 ft. The propulsion system design optimization minimizes the total energy required to fly the optimal path. It uses a combination of blade element momentum theory, blade composite structures, empirical motor and motor controller mass data, as well as a first order motor performance model. The battery optimization seeks to optimally size the battery for a circular orbit. Fixed point iteration between these optimization frameworks yields a flight path and propulsion system that slightly decreases solar capture, but significantly decreases power expended. Fully coupling the trajectory and design optimizations with this level of accuracy is infeasible with current computing resources. These efforts show the benefits of combining design and trajectory optimization to enable the feasibility of SR-HALE flight.

Using MIL-HDBK-419A, MATLAB and Nomographs, Shielding Effectiveness for the Magnetic Field, Electric Field, and Plane Wave were calculated over a frequency range from 10 Hz to 1 GHz. The three shielding tapes used included superalloy, aluminum, and mumetal. Calculations for Shielding Effectiveness involve the computation of Absorption Loss, Reflection Loss, and Re-Reflection Correction Factor. From the outcome of the calculations, it was suitable to conclude that all three metals fulfill the 40 dB Shielding Effectiveness requirements for SGEMP fields for frequencies greater or equal to 1 MHz. Accordingly, all three shielding tapes provide at least 40 dB of shielding to protect certain frequencies against SGEMP Magnetic Field. However, results vary for frequencies below 1 MHz.

New Horizons, Voyager 1 & 2, and Pioneer 10 & 11 are the only spacecraft to ever venture past Pluto and provide information about space at those large distances. These spacecraft were very expensive and primarily designed to study planets during gravitational assist maneuvers. They were not designed to explore space past Pluto and their study of this environment is at best a secondary mission. These spacecraft rely on radioisotope thermoelectric generators (RTGs) to provide power, an expensive yet necessary approach to generating sufficient power. With Cubesats graduating to interplanetary capabilities, such as the Mars-bound MarCO spacecraft, matching the modest payload requirements to study the outer Solar System (OSS) with the capabilities of low-power nano-satellites may enable much more affordable access to deep space. This paper explores a design concept for a low-cost, small spacecraft, designed to study the OSS and satisfy mission requirements with solar power. The general spacecraft design incorporates a parabolic reflector that acts as both a solar concentrator and a high gain antenna. This paper explores a working design concept for a small spacecraft to operate up to 100 astronomical units (AU) from the sun. Deployable reflector designs, thermal and radiation environments, communications and power requirements, solar system escape trajectory options, and scientific payload requirements are detailed, and a working system is proposed that can fulfill mission requirements with expected near-future innovations in a few key technologies.

In this thesis, the development of a structure for use in an educational CubeSat kit is explored. The potential uses of this kit include augmenting existing curricula with aspects of hands on learning, developing new ways of training students on proper space systems engineering practices, and overall contributing to academic capacity building at Cal Poly and its collaborators. The design improves on existing CubeSat kit structures by increasing accessibility to internal components by implementing a modular backplane system, as well as adding the ability to be environmentally tested. Manufacturing of the structure is completed with both additive (Fused Deposition Modeling with ABS polymer and Selective Laser Melting with AlSi10Mg metal) and subtractive (milling with Al-6061) technologies. Modal, harmonic, and random vibration analyses and tests are done to ensure the structure passes vibration testing qualification loads, as outlined by the National Aeronautics and Space Administration’s General Environmental Standards. Successful testing of the structure, defined as deforming less than 0.5 millimeters and maintaining a factor of safety above 2, is achieved with all materials of interest. Thus, the structure becomes the first publicly available CubeSat kit designed to survive environmental testing. Achieving this goal with a structure made of the cheap, widely available material ABS showcases the potential usability of 3D-printed polymers in CubeSat structures.

The CalPoly Spacecraft Attitude Dynamics Simulator mimics the rotational dynamics of a spacecraft in orbit and acts as a testbed for spacecraft attitude control system development and demonstration. Prior to this thesis, the simulator platform and several subsystems had been designed and manufactured, but the total simulator system was not yet capable of closed-loop attitude control. Previous attempts to make the system controllable were primarily mired by data transport performance. Rather than exporting data to an external command computer, the strategy implemented in this thesis relies on a compact computer onboard the simulator platform to handle both attitude control processing and data acquisition responsibilities. Software drivers were created to interface the computer’s data acquisition boards with Matlab, and a Simulink library was developed to handle hardware interface functions and simplify the composition of attitude control schemes. To improve the usability of the system, a variety of actuator control, hardware testing, and data visualization utilities were also created. A closedloop attitude control strategy was adapted to facilitate future sensor installations, and was tested in numerical simulation. The control model was then updated to interface with the simulator hardware, and for the first time in the project history, attitude control was performed onboard the CalPoly spacecraft attitude dynamics simulator. The demonstration served to validate the numerical model and to verify the functionality of the entire simulator system.