Mechanical Engineering Commons^™

Understanding The Mechanical Behavior Of Costal Cartilage At Their Curved Exterior Surface Via A Tactile Sensor With A Built-In Probe For Distributed-Deflection Detection, Jiayue Shen

Mechanical & Aerospace Engineering Theses & Dissertations

This dissertation is aimed to determine the mechanical properties at the exterior surface of costal cartilages (CC) and examine how they vary with the cartilage length and the anatomical sites of CC in the ribcage via conformal indentation testing which is built upon a tactile sensor for distributed-deflection detection. The sensor entails a rectangular Polydimethylsiloxane (PDMS) microstructure sensing-plate integrated with a 5 ×1 transducer array with 0.75mm spatial resolution underneath and a built-in probe of 0.5mm×5mm×3mm above. By pressing the sensor against the exterior surface of a CC tissue with a pre-defined indentation pattern, the sensor conforms to the curved …

A Cost Effective Design For A Propeller Thrust/Torque Balance, Nicholas Barrett Sadowski

Mechanical & Aerospace Engineering Theses & Dissertations

Wind tunnel balances are used with aircraft models, propellers, and components to measure applied forces and moments. The design and manufacture of a balance is often for a specific test, test article and conditions. This paper discusses the theory, design, calibration, and testing of a new small propeller balance for use in a low-speed wind tunnel. The new balance is named the ODU15X15.

Theory discussed herein covers how the two measurement components, thrust and torque, affect the balance design. These loads generate strains which are in turn read by strain gages arranged in Wheatstone bridges. The design follows well known …

Distributed Sensing And System Identification Of Cantilever Beams And Plates In The Presence Of Weak Nonlinearities, Patrick Sean Heaney

Mechanical & Aerospace Engineering Theses & Dissertations

While the mathematical foundation for modal analysis of continuous systems has long been established, flexible structures have become increasingly widespread and developing tools for understanding their mechanics has become increasingly important. Cantilever beams and plates, in particular, have been extensively studied due to their practical importance as approximations of more complex structures. The focus of this thesis is on understanding the dynamics of vibrating cantilever beams and plates through analytical and experimental investigation. Various models for the mechanics of these structures, of varying physical fidelity, are described and compared. A fiber optic sensing system is utilized to experimentally acquire distributed …

Investigation Of Microfluidic Kelvin Water Dropper And Its Applications In Contact And Contactless Electrowetting, Elias Yazdanshenas

Mechanical & Aerospace Engineering Theses & Dissertations

A typical Kelvin water dropper is a device that can convert gravitational potential energy to a high voltage electrostatic. This device consists of two inductors, two collectors, tubes, and electrical connections. A Kelvin water dropper is able to generate extremely high voltage by separating ions using two positive feedback loops. A Kelvin water dropper provides a low cost solution for the applications in which high voltage is needed. In the present research, low cost Microfluidic Kelvin Water Droppers (MKWDs) were developed and built in house for electrowetting applications. Two MKWDs with different tube inner diameters (254 and 508 μm) were …

Simplified, Alternative Formulation Of Numerical Simulation Of Proton Exchange Membrane Fuel Cell, Russell L. Edwards

Mechanical & Aerospace Engineering Theses & Dissertations

Three-Dimensional proton exchange fuel cell (PEMFC) operation in steady-state is simulated with computational fluid dynamics / multiphysics software that is based upon the finite-element method. PEMFC operation involves the simultaneous simulation of multiple, interconnected physics involving fluid flows, heat transport, electrochemical reactions, and both protonic and electronic conduction. Modeling efforts have varied by how they treat the physics occurring within and adjacent to the membrane-electrode assembly (MEA). Several approaches treat the MEA as part of the computational domain, solving multiple, and coupled conservation equations via the CFD approach within the 3 regions of the MEA. The thickness dimensions of the …

Robocatch: Design And Making Of A Hand-Held Spillage-Free Specimen Retrieval Robot For Laparoscopic Surgery, Farid Tavakkolmoghaddam

Mechanical & Aerospace Engineering Theses & Dissertations

Specimen retrieval is an important step in laparoscopy, a minimally invasive surgical procedure performed to diagnose and treat a myriad of medical pathologies in fields ranging from gynecology to oncology. Specimen retrieval bags (SRBs) are used to facilitate this task, while minimizing contamination of neighboring tissues and port-sites in the abdominal cavity. This manual surgical procedure requires usage of multiple ports, creating a traffic of simultaneous operations of multiple instruments in a limited shared workspace. The skill-demanding nature of this procedure makes it time-consuming, leading to surgeons’ fatigue and operational inefficiency. This thesis presents the design and making of RoboCatch, …

A Scientific Approach To Understanding The Head Trauma Endured By A Mixed Martial Arts Fighter, John William Michael Sorbello

Mechanical & Aerospace Engineering Theses & Dissertations

The purpose of this research is to gain some insight on the type of head trauma an athlete may encounter during mixed martial arts (MMA) competition. These athletes endure continuous blows to the head throughout their training and fighting career. The knowledge obtained from this research may assist MMA athletes and trainers in assessing the way they train, how they compete and, more importantly, how long they choose to compete in their amateur or professional MMA career.

The analysis is performed by first creating a three-dimensional solid model of the human head based on geometric coordinates originally obtained from a …

Offshore Wind Energy: Simulating Local Offshore Wind Turbine, Ian P. Aquino

Mechanical & Aerospace Engineering Theses & Dissertations

Dominion Virginia Energy is looking at the possible creation of an offshore wind plant as a renewable source of electricity to be located off the coast of Virginia Beach. This thesis reports on a computer simulation based on local wind conditions and possible single wind turbine installation.

The National Buoy Data Center keeps records of the local wind conditions gathered in real time and available to the public. These data give a general overview of the wind conditions in Virginia Beach which is used to simulate atmospheric boundary layer (ABL) flow conditions and is subsequently used as input data for …

Dynamic Response Modeling Of High Speed Planing Craft With Enforced Acceleration, Brian K. Johnson

Mechanical & Aerospace Engineering Theses & Dissertations

Due to the harsh conditions high speed planing crafts must endure, research to further the understanding of high speed vessel response during wave impacts was conducted. The integration of a finite element model and captured sea trial acceleration data was investigated. The research shows that the finite element model sub-model can be used in lieu of a full finite element model with minimum degradation in output, thus allowing for the analysis of local stress concentrations where critical equipment and or personnel may be located.

The research effort was completed to develop a method for realizing the stress field and deformation …

Human-Robot Collaborative Force-Controlled Micro-Drilling For Advanced Manufacturing And Medical Applications, Parimal Mahesh Prajapati

Mechanical & Aerospace Engineering Theses & Dissertations

Robotic drilling finds applications in diverse fields ranging from advanced manufacturing to the medical industry. Recent advances in low-cost, and human-safe, collaborative robots (e.g., Sawyer) are enabling us to rethink the possibilities in which robots can be deployed for such tedious and time-consuming tasks. This thesis presents a robotic drilling methodology with features of force-control enabled micro-drilling and human-robot collaboration to reduce programming efforts and enhance drilling performance. A Sawyer robot from Rethink Robotics, which offers safe physical interactions with a human co-worker, kinesthetic teaching, and force control, is used as the test bed. The robot’s end-effector was equipped with …

A Monolithic Internal Strain-Gage Balance Design Based On Design For Manufacturability, Thomas Ladson Webb Iii

Mechanical & Aerospace Engineering Theses & Dissertations

This paper proposes an alternative approach to internal strain-gage balance design driven by Design for Manufacturability (DFM) principles. The objective of this research was a reduction in fabrication time and, subsequently, cost of a balance by simplifying its design while maintaining basic stiffness and sensitivity. Traditionally, the National Aeronautics and Space Administration (NASA) Langley Research Center (LaRC) balance designs have relied on Electro-Discharge Machining (EDM), which is a precise but slow and, therefore, expensive process. EDM is chosen due to several factors, including material hardness, surface finish, and complex geometry, including blind cuts. The new balance design objectives require no …

Using Optimality Theory And Reference Points To Improve The Diversity And Convergence Of A Fuzzy-Adaptive Multi-Objective Particle Swarm Optimizer, Amit A. Kulkarni

Mechanical & Aerospace Engineering Theses & Dissertations

Particle Swarm Optimization (PSO) has received increasing attention from the evolutionary optimization research community in the last twenty years. PSO is a metaheuristic approach based on collective intelligence obtained by emulating the swarming behavior of bees. A number of multi-objective variants of the original PSO algorithm that extend its applicability to optimization problems with conflicting objectives have also been developed; these multi-objective PSO (MOPSO) algorithms demonstrate comparable performance to other state-of-the-art metaheuristics. The existence of multiple optimal solutions (Pareto-optimal set) in optimization problems with conflicting objectives is not the only challenge posed to an optimizer, as the latter needs to …

Computational Methods For Nonlinear Systems Analysis With Applications In Mathematics And Engineering, Geoffrey Kenneth Rose

Mechanical & Aerospace Engineering Theses & Dissertations

An investigation into current methods and new approaches for solving systems of nonlinear equations was performed. Nontraditional methods for implementing arc-length type solvers were developed in search of a more robust capability for solving general systems of nonlinear algebraic equations. Processes for construction of parameterized curves representing the many possible solutions to systems of equations versus finding single or point solutions were established. A procedure based on these methods was then developed to identify static equilibrium states for solutions to multi-body-dynamic systems. This methodology provided for a pictorial of the overall solution to a given system, which demonstrated the possibility …

Development Of A Data Acquisition System For Unmanned Aerial Vehicle (Uav) System Identification, Donald Joseph Lear

Mechanical & Aerospace Engineering Theses & Dissertations

Aircraft system identification techniques are developed for fixed wing Unmanned Aerial Vehicles (UAV). The use of a designed flight experiment with measured system inputs/outputs can be used to derive aircraft stability derivatives. This project set out to develop a methodology to support an experiment to model pitch damping in the longitudinal short-period mode of a UAV. A Central Composite Response Surface Design was formed using angle of attack and power levels as factors to test for the pitching moment coefficient response induced by a multistep pitching maneuver.

Selecting a high-quality data acquisition platform was critical to the success of the …

Development Of The Compact Jet Engine Simulator From Concept To Useful Test Rig, Henry H. Haskin

Mechanical & Aerospace Engineering Theses & Dissertations

NASA had a goal to develop a set of modeling tools for designing next generation civil transport aircraft with reduced noise, emissions and increased fuel efficiency by 2016. To verify the models, a database of aerodynamic and acoustic data was needed for an unconventional flying wing design that was predicted to meet the goals. A Compact Jet Engine Simulator (CJES) was needed as the jet source for the 5.8% scale model. Ultra-Compact Combustor Technology from the Air Force Research Laboratory was used to reduce the conventional burner acoustic test rigs down to the required scale size. The Air Force design …

The Effect Of Bone And Ligament Morphology Of Ankle Joint Loading In The Neutral Position, Jinhyuk Kim

Mechanical & Aerospace Engineering Theses & Dissertations

Computational modeling of joints is used to investigate the effect of injuries, to plan surgeries, and to answer questions about joints that cannot be answered experimentally. Existing models of the ankle joint are moving toward being able to model specific patients, however, they do not include all of the anatomy (e.g., bones and/or ligaments) and have restrictive boundary conditions. These simplification in anatomy are made to minimize pre-processing and computation time. Because biomechanical modeling is increasingly focused on the implementation of patient specific cases, the effects of including more anatomical structures and determining how they affect the model results is …

Investigation, Modeling And Validation Of Digital Bridge For A New Generation Hot-Wire Anemometer, Karthik Kamalakar Joshi

Mechanical & Aerospace Engineering Theses & Dissertations

The Digital Bridge Thermal Anemometer (DBTA) is a new generation anemometer that uses advanced electronics and a modified half-Wheatstone bridge configuration, specifically a sensor and a shunt resistor in series. This allows the miniaturization of the anemometer and the communication between host computer and anemometer is carried out using serial or ethernet which eliminates the noise due to the use of long cables in conventional anemometer and the digital data sent to host computer is immune to electrical noise. In the new configuration the potential drop across a shunt resistor is used to control the bridge.

This thesis is confined …

A Low Cost Inflatable Cubesat Drag Brake Utilizing Sublimation, Adam Charles Horn

Mechanical & Aerospace Engineering Theses & Dissertations

The United Nations Inter-Agency Debris Coordination Committee has adopted a 25-year post-mission lifetime requirement for any satellite orbiting below 2000 km in order to mitigate the growing orbital debris threat. Low-cost CubeSats have become important satellite platforms with startling capabilities, but this guideline restricts them to altitudes below 600 km because they remain in orbit too long. In order to enable CubeSat deployments at higher release altitudes, a low-cost, ultra-reliable deorbit device is needed.

This thesis reports on efforts to develop a deployable and passively inflatable drag brake that can deorbit from higher orbital altitudes, thereby complying with the 25-year …

Optimal Ship Maintenance Scheduling Under Restricted Conditions And Constrained Resources, Vi Hong Nguyen

Mechanical & Aerospace Engineering Theses & Dissertations

The research presented in this dissertation addresses the application of evolution algorithms, i.e. Genetic Algorithm (GA) and Differential Evolution algorithm (DE) to scheduling problems in the presence of restricted conditions and resource limitations. This research is motivated by the scheduling of engineering design tasks in shop scheduling problems and ship maintenance scheduling problems to minimize total completion time. The thesis consists of two major parts; the first corresponds to the first appended paper and deals with the computational complexity of mixed shop scheduling problems. A modified Genetic algorithm is proposed to solve the problem. Computational experiments, conducted to evaluate its …

Development Of An Analysis And Design Optimization Framework For Marine Propellers, Ashish C. Tamhane

Mechanical & Aerospace Engineering Theses & Dissertations

In this thesis, a framework for the analysis and design optimization of ship propellers is developed. This framework can be utilized as an efficient synthesis tool in order to determine the main geometric characteristics of the propeller but also to provide the designer with the capability to optimize the shape of the blade sections based on their specific criteria.

A hybrid lifting-line method with lifting-surface corrections to account for the three-dimensional flow effects has been developed. The prediction of the correction factors is achieved using Artificial Neural Networks and Support Vector Regression. This approach results in increased approximation accuracy compared …

Multi-Mode Resource Constrained Project Scheduling Using Differential Evolution Algorithm, Faisal Manour Altarazi

Mechanical & Aerospace Engineering Theses & Dissertations

Project scheduling is a tool that manages the work and resources associated with delivering a project on time. Project scheduling is important to organize, keep track of the finished and in-progress tasks and manage the quality of work delivered. However, many problems arise during project scheduling. Minimizing project duration is the primary objective. Project cost is also a critical matter, but there will always be a trade off between project time and cost (Ghoddousiet et al., 2013), so scheduling activities can be challenging due to precedence activities, resources, and execution modes. Schedule reduction is heavily dependent on the availability of …

An Examination Of The Indentation Size Effect In Fcc Metals And Alloys From A Kinetics Based Perspective Using Nanoindentation, David Earl Stegall

Mechanical & Aerospace Engineering Theses & Dissertations

The indentation size effect (ISE) in metals is described as the rise in hardness with decreasing depth of indentation and contradicts conventional plasticity behavior. The goal of this dissertation is to further examine the fundamental dislocation mechanisms that may be contributing to the so-called indentation size effect. In this work, we examined several metals and alloys including 99.999% Aluminum (SFE ~200 mJ/m²), 99.95% Nickel (SFE ~125 mJ/m²), 99.95% Silver (SFE ~22 mJ/m²⁾, and three alloys, alpha brass 70/30 (SFE >10 mJ/m²), 70/30 nickel copper (SFE ~100 mJ/ …

Testing And Analysis Of An Exergetically Efficient 4 K To 2 K Helium Heat Exchanger, Peter N. Knudsen

Mechanical & Aerospace Engineering Theses & Dissertations

Modern experimental nuclear physics programs that utilize advanced superconducting devices require refrigeration below the lambda temperature of helium (2.1768 K) and involve sub-atmospheric helium at some point in the process. They typically operate between 1.8 and 2.1 K (16 to 40 mbar) and can require refrigeration ranging from tens to thousands of watts. These processes are very energy intensive, requiring roughly 850 W/W even for large and well-designed refrigerators, though they can easily require much more. Adiabatic expansion of sub-cooled liquid helium to these sub-atmospheric pressures will result in a two-phase mixture with a large liquid to vapor density ratio. …

Thermo-Mechanical System Identification Of A Shape Memory Alloy Actuated Mechanism, Cody Alexander Wright

Mechanical & Aerospace Engineering Theses & Dissertations

Shape memory alloy (SMA) actuators paired in an antagonistic arrangement can be used to produce mechanisms that replicate human biomechanics. To investigate this proposal, the biomechanical articulation of the elbow by means of the biceps brachii muscle is compared with that of a SMA actuated arm. This is accomplished by parametric analysis of a crank-slider kinematic mechanism actuated, first, with an experimentally characterized SMA wire and then an idealized musculotendon actuator based on actuation properties of muscles published in the literature. Next, equations of motion for the system dynamics of the SMA actuated mechanism are derived and phase portrait analysis …

Development Of A Dsm-Based Model For Managing The Design Of Complex Systems Considering The Impact Of Technological Obsolescence, Gershom Kwaku Obeng

Mechanical & Aerospace Engineering Theses & Dissertations

Obsolescence has been a constant issue for process planners and designers and if not properly accounted for, obsolescence can become an expensive issue. As systems become more complex, interconnected, and nonhomogeneous, separate studies of single groups of equipment are no longer sufficient in modeling the obsolescence of the systems that they make up. The purpose of this dissertation is to model the likelihood of a process's design becoming obsolescent given the obsolescent behavior of the equipment used to complete the process. The methodology discussed in this work is based on a combination of using a systems engineering tool called the …

Parametric Investigation Of A Laboratory Drop Test To Simulate Base Acceleration Induced By Wave Impacts Of High Speed Planing Craft, John D. Barber

Mechanical & Aerospace Engineering Theses & Dissertations

High speed operations in a small craft can be physically punishing and, in some circumstances, even dangerous for the crew. The aspect of small craft operations that make them punishing for the crew is wave slamming generated by wave impacts as the craft is traveling over the seas at high speed.

The initial step of this thesis effort was to perform a literature survey to determine what knowledge existed within the technical and academic community about wave slamming and simulating them with drop tests.

Eventually, a final experiment strongly influenced by the experiment model found in (Protocol 1, 2014) was …

A Comparison Of Microstructure And Uniaxial Compressive Response Of Ice-Templated Porous Alumina Scaffolds Fabricated From Two Different Particle Sizes, Nikhil D. Dhavale

Mechanical & Aerospace Engineering Theses & Dissertations

Development of bio-inspired highly porous (>50 vol.%) cellular ceramics is crucial to meet the demand of high-performance lightweight and damage-tolerant materials for a number of cutting-edge applications including impact energy absorption, biomedical implants, and energy storage. A key design feature that is observed in many natural materials (e.g., nacre, bamboo, wood, etc.) is the presence of hierarchical microstructure that results in an excellent synergy of various material properties, which are otherwise considered as mutually exclusive in current paradigm of materials design. To this end, development of multilayered, interconnected and anisotropic cellular ceramics could benefit the aforementioned applications. However, mimicking …

Development Of The Compact Jet Engine Simulator From Concept To Useful Test Rig, Henry H. Haskin

Mechanical & Aerospace Engineering Theses & Dissertations

Two Compact Jet Engine Simulator (CJES) units were designed for integrated wind tunnel acoustic experiments involving a Hybrid Wing Body (HWB) vehicle. To meet the 5.8% scale of the HWB model, Ultra Compact Combustor technology from the Air Force Research Laboratory was used. The CJES units were built and integrated with a control system in the NASA Langley Low Speed Aero acoustic Wind Tunnel. The combustor liners, plug—vane and flow conditioner components were built in-house at Langley Research Center. The operation of the CJES units was mapped and fixes found for combustor instability tones and rig flow noise. The original …

Carbon Deposition During Oxygen Production Using High Temperature Electrolysis And Mitigation Methods, Timothy Adam Bernadowski

Mechanical & Aerospace Engineering Theses & Dissertations

Carbon dioxide in the Martian atmosphere can be converted to oxygen during high temperature electrolysis for use in life-support and fuel systems on manned missions to the red planet. During electrolysis of carbon dioxide to produce oxygen, carbon can deposit on the electrolysis cell resulting in lower efficiency and possibly cell damage. This would be detrimental, especially when the oxygen product is used as the key element of a space life support system. In this thesis, a theoretical model was developed to predict hazardous carbon deposition conditions under various operating conditions within the Martian atmosphere. The model can be used …

Constrained-Energy Cross-Well Actuation Of Bistable Structures, Masoud Zarepoor

Mechanical & Aerospace Engineering Theses & Dissertations

Bistable structures have two stable equilibrium positions and can be utilized to maintain a specific static shape with no energy consumption. This dissertation focuses on the minimum required energy for performing snap-through of a bistable structure. Snap-through is the motion of a bistable structure from one stable equilibrium position to the other. This research uses the Duffing-Holmes equation as a one-degree-of-freedom representative model of a bistable structure, and this nonlinear equation is solved to calculate the required energy for cross-well oscillation. The research identifies several unique features of the response of a bistable system subjected to force and energy constraints. …