Open Access. Powered by Scholars. Published by Universities.®

Mechanical Engineering Commons

Open Access. Powered by Scholars. Published by Universities.®

Dissertations and Theses

Discipline
Institution
Keyword
Publication Year

Articles 1 - 30 of 141

Full-Text Articles in Mechanical Engineering

Finite Element Model Validation And Testing Of An Off-Road Vehicle Under Dynamic Loading Conditions, Mackenzie Susan Cunningham Apr 2019

Finite Element Model Validation And Testing Of An Off-Road Vehicle Under Dynamic Loading Conditions, Mackenzie Susan Cunningham

Dissertations and Theses

In the vehicle design life cycle, validation tests consume a significant portion of the available development time. With a short, one-year design cycle, the Embry-Riddle Baja Team leverages computer-aided engineering (CAE) tools to simulate critical test cases whose loading conditions can be accurately represented by a series of static loads and constraints. Using these conditions, a Finite Element Model (FEM) can be employed to accurately predict the effects of the loading conditions in the components. During the initial design of the front suspension, one major load case was determined to be the main failure load. However, after validation testing the ...


Global Estimation Methodology For Wave Adaptation Modular Vessel Dynamics Using A Genetic Algorithm, Marco Alan Schoener Apr 2019

Global Estimation Methodology For Wave Adaptation Modular Vessel Dynamics Using A Genetic Algorithm, Marco Alan Schoener

Dissertations and Theses

Determining parameters for a system model for marine vessels becomes more difficult as the model is made more complex. Work has been done to determine the equations of motion, but not to fully define how to estimate all of the system parameters. This work utilizes a global optimization methodology for estimating the system parameters using a genetic algorithm. The optimizer uses training data sets created from a set of ship maneuvering standards to minimize the error in the 3 degree-of-freedom equations of motion. The model has been optimized using a “No Surge-Yaw” model (minimal surge coupling) and a “Full” model ...


Shape-Stabilization Of Pcm/Hdpe Composites With 3d-Printing Applications For Battery Thermal Management, Thomas Benjamin Freeman Dec 2018

Shape-Stabilization Of Pcm/Hdpe Composites With 3d-Printing Applications For Battery Thermal Management, Thomas Benjamin Freeman

Dissertations and Theses

Phase-change materials (PCMs) are a useful alternative to more traditional methods of thermal management of Li-ion batteries in electric or hybrid-electric vehicles. PCMs are materials which absorb large amounts of latent heat and undergo solid-to-liquid phase change at near-constant temperature. The goal of this thesis is to experimentally investigate the thermal properties of a novel shape-stabilized PCM/HDPE composite extruded filament. The extruded filament can then be used in a 3D printer for custom PCM/HDPE shapes. These custom PCM/HDPE shapes can be used to help reduce weight, energy consumption, and complexity of the thermal management of the ESS ...


Chemo-Thermo Cure Of Viscoelastic Materials For Semiconductor Packaging Applications, Anjali Pradeep Kumar Aug 2018

Chemo-Thermo Cure Of Viscoelastic Materials For Semiconductor Packaging Applications, Anjali Pradeep Kumar

Dissertations and Theses

Viscoelastic polymer materials are being actively considered as a novel material for semiconductor packaging applications as a result of their ability to develop strong adhesive bonds at lower temperatures. Viscoelastic thermoset materials are impacted by the stresses generated during the curing process, which is also accompanied by a dissipation of thermal energy. There is a need to develop a generic modeling formulation that is applicable to any material of interest in order to enable the study of different bonding materials and develop optimized curing cycles. This study reports a numerical formulation to evaluate the stress generated and energy dissipated during ...


Reliability Of Solder Joints In Embedded Packages Using Finite Element Methods, Valeri Aisha Yunusa Jul 2018

Reliability Of Solder Joints In Embedded Packages Using Finite Element Methods, Valeri Aisha Yunusa

Dissertations and Theses

Solder joints serve as both mechanical and electrical connections between elements in a package. They are subjected to shear strains generated as a result of the different behaviors of the elements in the package (tension and compression) due to the differences in coefficients of thermal expansion during service conditions.

Some of the causes of solder joint failures are due to the following:

Vibration: small rapid displacements of parts of the assembly. This is not necessarily an issue with electronic components but larger parts like automobiles.

Humidity: the package being exposed to water or ionic species can undergo corrosion if an ...


Emulating Balance Control Observed In Human Test Subjects With A Neural Network, Wade William Hilts Jul 2018

Emulating Balance Control Observed In Human Test Subjects With A Neural Network, Wade William Hilts

Dissertations and Theses

Human balance control is a complex feedback system that must be adaptable and robust in an infinitely varying external environment. It is probable that there are many concurrent control loops occurring in the central nervous system that achieve stability for a variety of postural perturbations. Though many engineering models of human balance control have been tested, no models of how these controllers might operate within the nervous system have yet been developed. We have focused on building a model of a proprioceptive feedback loop with simulated neurons. The proprioceptive referenced portion of human balance control has been successfully modeled by ...


Improving Seaglider Efficiency: An Analysis Of Wing Shapes, Hull Morphologies, And Propulsion Methods, Christopher James Hockley Jul 2018

Improving Seaglider Efficiency: An Analysis Of Wing Shapes, Hull Morphologies, And Propulsion Methods, Christopher James Hockley

Dissertations and Theses

Autonomous underwater gliders are a family of autonomous underwater vehicles used for long-term observation of oceanic environments. These gliders leverage changes in buoyancy and the resulting vertical motion, to generate forward locomotion via hydrodynamic surfaces. In order to function for extended periods, these systems operate in a low-speed, low-drag regime. This research examines factors impacting the operational efficiencies of gliders, including morphological changes, configuration changes, and propulsion. An interesting question arises when considering the operational efficiencies of conventionally propelled systems at the operating speeds typical of gliders. Can a conventional propulsion system match the efficiency of an underwater glider buoyancy ...


Sensitivity Analyses Of Optimized Attitude Estimators Using Sensor Fusion Solutions For Low-Cost Mems Configurations, Ryan W. Hoffman Jul 2018

Sensitivity Analyses Of Optimized Attitude Estimators Using Sensor Fusion Solutions For Low-Cost Mems Configurations, Ryan W. Hoffman

Dissertations and Theses

Since the 1990’s, there has been increased focus on creating navigation systems for small unmanned systems, particularly small unmanned aerial systems (SUAS). Due to size, weight, and cost restrictions, compared to larger more costly manned systems, navigation systems for SUAS have evolved to be quite different from the proven systems of the past. Today, there are many solutions for the problem of navigation for SUAS. The problem has now become choosing the most fitting navigation solution for a given application/mission. This is particularly true for evaluating solutions that are fundamentally different.

This research analyses the performance and sensitivity ...


Biomimetic Design And Construction Of A Bipedal Walking Robot, Alexander Gabriel Steele Jun 2018

Biomimetic Design And Construction Of A Bipedal Walking Robot, Alexander Gabriel Steele

Dissertations and Theses

Human balance and locomotion control is highly complex and not well understood. To understand how the nervous system controls balance and locomotion works, we test how the body responds to controlled perturbations, the results are analyzed, and control models are developed. However, to recreate this system of control there is a need for a robot with human-like kinematics. Unfortunately, such a robotic testbed does not exist despite the numerous applications such a design would have in mobile robotics, healthcare, and prosthetics.

This thesis presents a robotic testbed model of human lower legs. By using MRI and CT scans, I designed ...


Wind Energy And Wind-Energy-Inspired Turbulent Wakes: Modulation Of Structures, Mechanisms And Flow Regimes, Elizabeth H. Camp Jun 2018

Wind Energy And Wind-Energy-Inspired Turbulent Wakes: Modulation Of Structures, Mechanisms And Flow Regimes, Elizabeth H. Camp

Dissertations and Theses

The interaction of turbulent wakes with one another and with the adjacent fluid directly impacts the generation of electricity in wind turbine arrays. Computational modeling is well suited to the repeated iterations of data generation that may be required to inform understanding of the function of wind farms as well as to develop control schemes for plant function. In order to perform such computational studies, a simplified model of the turbine must be implemented. One of the most computationally efficient parametrizations of the blade utilizes a stationary disk which has a prescribed drag and produces a wake. However, since accurate ...


An Underwater Vehicle Navigation System Using Acoustic And Inertial Sensors, Khalid M. Alzahrani May 2018

An Underwater Vehicle Navigation System Using Acoustic And Inertial Sensors, Khalid M. Alzahrani

Dissertations and Theses

Unmanned Underwater Vehicles (UUVs) have become an essential tool for different underwater tasks. Compared with other unmanned systems, the navigation and localization for UUVs are particularly challenging due to the unavailability of Global Positioning System (GPS) signals underwater and the complexity of the unstable environment. Alternative methods such as acoustic positioning systems, Inertial Navigation Systems (INS), and the geophysical navigation approach are used for UUV navigation. Acoustic positioning systems utilize the characteristics of acoustic signals that have a lower absorption rate and a more extended propagation distance than electromagnetic signals underwater. The significant disadvantage of the INS is the “drift ...


Design Optimization For A Cnc Machine, Alin Resiga Apr 2018

Design Optimization For A Cnc Machine, Alin Resiga

Dissertations and Theses

Minimizing cost and optimization of nonlinear problems are important for industries in order to be competitive. The need of optimization strategies provides significant benefits for companies when providing quotes for products. Accurate and easily attained estimates allow for less waste, tighter tolerances, and better productivity. The Nelder-Mead Simplex method with exterior penalty functions was employed to solve optimum machining parameters. Two case studies were presented for optimizing cost and time for a multiple tools scenario. In this study, the optimum machining parameters for milling operations were investigated. Cutting speed and feed rate are considered as the most impactful design variables ...


Multi-Scale Fluid Flow Analysis Of The Cardiovascular System, Zaid Mahmood Apr 2018

Multi-Scale Fluid Flow Analysis Of The Cardiovascular System, Zaid Mahmood

Dissertations and Theses

The hypoplastic left heart syndrome (HLHS) is one of the rarest congenital heart diseases affecting infants. Out of 150 babies born, one baby suffers from congenital heart disease. Furthermore, nine percent out of those suffering from congenital heart disease specifically suffer from hypoplastic left heart syndrome (HLHS). To this end, the Fontan operation which is a procedure to generate a harmonic blood flow in single functioning ventricle patients has been executed to palliate HLHS patients. In this operation, the inferior vena cava (IVC) and the superior vena cava (SVC), carrying the low-oxygenated blood returning from the lower and upper body ...


Relationship Between Anisotropy And Dispersive Stress In Wind Plants With Variable Spacing, Tamara S. Dib Mar 2018

Relationship Between Anisotropy And Dispersive Stress In Wind Plants With Variable Spacing, Tamara S. Dib

Dissertations and Theses

Large eddy simulations are considered for wind plants with varied spanwise and streamwise spacing. Data from five different configurations of staggered and aligned LES wind turbine arrays with a neutrally stratified atmospheric boundary layer are employed for analysis. Fields are analyzed by evaluating the anisotropy stress invariants based on the Reynolds shear stresses and dispersive stress tensor. The relationship between quantities are drawn as a function of the wind plant packing. Reynolds stresses and dispersive stresses are investigated alongside a domain altered version of the second and third scalar invariants, ξ, η, as well as the combination of the two ...


Stress Analysis Of Embedded Devices Under Thermal Cycling, Sadhana Radhakrishnan Jan 2018

Stress Analysis Of Embedded Devices Under Thermal Cycling, Sadhana Radhakrishnan

Dissertations and Theses

Embedded active and passive devices has been increasingly used by in order to integrate more functions inside the same or smaller size device and to meet the need for better electrical performance of the component assemblies.

Solder joints have been used in the electronic industry as both structural and electrical interconnections between electronic packages and printed circuit boards (PCB). When solder joints are under thermal cyclic loading, mismatch in coefficients of thermal expansion (CTE) between the printed circuit boards and the solder balls creates thermal strains and stresses on the joints, which may finally result in cracking. Consequently, the mechanical ...


Computational Investigation Of The Biomechanics Of Babywearing In Regards To Developmental Dysplasia Of The Hip, Gaurav Girish Dec 2017

Computational Investigation Of The Biomechanics Of Babywearing In Regards To Developmental Dysplasia Of The Hip, Gaurav Girish

Dissertations and Theses

Developmental Dysplasia of the Hip (DDH) is a congenital condition where an infant’s hip socket is either loose or otherwise unstable. DDH causes a joint instability where the femoral head is not properly situated inside the acetabulum. Etiology of the condition is in part congenital and developmental, with a difference of DDH prevalence between ethnicities. Incidence of DDH is also in some part dependent on cultural practices and activities of the mother and child. The exact nature of this cultural incidence is not clearly understood. A computational approach is hypothesized to identify the impact of babywearing position on the ...


Maritime Object Detection, Tracking, And Classification Using Lidar And Vision-Based Sensor Fusion, David John Thompson Nov 2017

Maritime Object Detection, Tracking, And Classification Using Lidar And Vision-Based Sensor Fusion, David John Thompson

Dissertations and Theses

Autonomous Surface Vehicles have the capability of replacing dull, dirty, and dangerous jobs in the maritime field. However, few successful ASV systems exist today, as there is a need for greater sensing capabilities. Furthermore, a successful ASV system requires object detection and recognition capabilities to enable autonomous navigation and situational awareness. This thesis demonstrates an application of LiDAR sensors in maritime environments for object detection, classification, and camera sensor fusion. This is accomplished through the integration of a high-fidelity GPS/INS system, 3D LiDAR sensors, and a pair of cameras. After rotating LiDAR returns into a global reference frame, they ...


Mission Tasking, Path Planning, And System Integration For An Autonomous Surface Vessel, Timothy Zuercher Nov 2017

Mission Tasking, Path Planning, And System Integration For An Autonomous Surface Vessel, Timothy Zuercher

Dissertations and Theses

This thesis presents the design and development of a fully autonomous surface vessel for use as a research platform for the Office of Naval Research and as a competition entry to the International Maritime RobotX Challenge in 2014 and 2016. The author’s contributions to this include the development of safety systems, power distribution systems, communications software, tasking software, and planning algorithms. The results of these developments include a hardware based safety system, a modular power and health monitoring system, an easy to use autoconfiguring inter-process communications stack, a dynamic tasking engine, and a comparison of two solutions to planning ...


Reduced Order Description Of Experimental Two-Phase Pipe Flows: Characterization Of Flow Structures And Dynamics Via Proper Orthogonal Decomposition, Bianca Fontanin Viggiano Aug 2017

Reduced Order Description Of Experimental Two-Phase Pipe Flows: Characterization Of Flow Structures And Dynamics Via Proper Orthogonal Decomposition, Bianca Fontanin Viggiano

Dissertations and Theses

Multiphase pipe flow is investigated using proper orthogonal decomposition for tomographic X-ray data, where holdup, cross-sectional phase distributions and phase interface characteristics within the pipe are obtained. Six cases of stratified and mixed flow with water content of 10%, 30% and 80% are investigated to gain insight into effects of velocity and proportion of water on the flow fields. Dispersed and slug flows are separately analyzed to consider the added interface complexity of the flow fields. These regimes are also highly applicable to industry operational flows. Instantaneous and fluctuating phase fractions of the four flow regime are analyzed and reduced ...


Supervisory Controls Strategy To Reduce Utility Factor Weighted Criteria Emissions For A Plug-In Hybrid Electric Vehicle, Thomas Francis Gorgia Iii May 2017

Supervisory Controls Strategy To Reduce Utility Factor Weighted Criteria Emissions For A Plug-In Hybrid Electric Vehicle, Thomas Francis Gorgia Iii

Dissertations and Theses

Criteria emission reduction techniques are being more sought out in the automotive industry due to current government regulation for light duty vehicles. Parallel-series plug in hybrid electric vehicles can have multiple strategies to balance emissions and fuel consumption. Common controls strategies in industry target fuel economy by using a large electric vehicle range, known as charge depletion, followed by maintaining a state of charge after a specific vehicle threshold, or charge sustaining. A charge preserve strategy works by running an engine at an optimal loading condition, the engine will burn the fuel more complete reducing criteria emissions. Charge preserve will ...


Numerical Investigation Of A Phase-Change Material Based Photovoltaic Panel Temperature Regulation System, Rohit Gulati May 2017

Numerical Investigation Of A Phase-Change Material Based Photovoltaic Panel Temperature Regulation System, Rohit Gulati

Dissertations and Theses

As the production of clean electricity has gained importance, photovoltaic (PV) panels have become a widely used technology. But, during operation, PV panels heat up due to the solar insolation and suffer a drop in electrical output. The goal of this investigation is to use phase-change materials (PCM) to passively cool PV panels. The PCM is inside an aluminum container attached to the back surface of the PV panel. Four configurations of the container are investigated. The first configuration is a container with bulk PCM occupying its entire interior volume. The depth of this container is varied. The second configuration ...


Development Of An Emulated Free-Floating Environment For On-Earth Testing Of Space Robots, Narendran Muraleedharan May 2017

Development Of An Emulated Free-Floating Environment For On-Earth Testing Of Space Robots, Narendran Muraleedharan

Dissertations and Theses

The ability to perform experiments on space robotic systems within a laboratory setting is crucial to development and testing of satellites and space robots prior to launch. One of the most widely used techniques which recreate the on-orbit motion of space robots and targets is hardware-in-the-loop simulation. This method requires extensive knowledge of the space robot model dynamic parameters. This research proposes a method which uses force feedback to control a robotic platform on which the space robot is mounted. The robotic platform is driven in such a way that the gravity-compensated forces and torques at the mounting interface are ...


Ab Initio Computation Of Radiative Properties Of Monatomic Hydrogen, Fanny Thomas May 2017

Ab Initio Computation Of Radiative Properties Of Monatomic Hydrogen, Fanny Thomas

Dissertations and Theses

With renewed interest in planetary atmospheric entry, descent, and landing, NASA has noted a need for improved physics modeling in computational fluid dynamics. Uncertainty in experimental data used in radiation heat transfer computations leads to “over-engineering” of entry body heat shields, at large weight and cost penalties. There is interest in developing hypersonic thermophysics models from the known “first principles” of physics.

A method for computing high temperature gas emissivity and absorptivity from quantum mechanics principles is developed. The Schroedinger wave equation is cast as a discretized matrix eigenvalue problem which is solved using the ERAU parallel supercomputer. The numerical ...


Dynamic Understeer Control Using Active Rear Toe, Mark Oliver Dixon Kaufman Apr 2017

Dynamic Understeer Control Using Active Rear Toe, Mark Oliver Dixon Kaufman

Dissertations and Theses

This thesis was conducted to show the ability of Active Rear Toe to control the understeer characteristics of a vehicle. Active rear toe is the ability to control the angle of the rear wheels around the vertical axis, allowing the car’s turning radius to change. By changing this radius, the lateral acceleration can be controlled, therefore the understeer of the vehicle can be controlled. The controls scheme is a sliding mode control, specifically a hyperbolic tangent boundary layer and a type 1 zeno controller. The system shows effectiveness to control the understeer of the vehicle up until limit grip ...


Multi-Agent Path Planning For Locating A Radiating Source In An Unknown Environment, Stephanie M. Schwartz Apr 2017

Multi-Agent Path Planning For Locating A Radiating Source In An Unknown Environment, Stephanie M. Schwartz

Dissertations and Theses

A situation is addressed in which multiple autonomous agents are used to search an unknown environment for a target, the position and orientation of which is known with respect to each agent. A controlling framework is proposed to inform and coordinate the agents’ movements in order to reduce the time required to locate the target. Four primary variables are considered: the cost function used to select the agents’ paths, the number of agents in a given scenario, the distance over which the agents are assumed to communicate, and the size of the environment in which the agents are operating. It ...


Computational Modeling Of Thoracic Injury Response Due To Impact Of A Small Unmanned Aerial System (Suas), Alexander Fumiyoshi Dori Mar 2017

Computational Modeling Of Thoracic Injury Response Due To Impact Of A Small Unmanned Aerial System (Suas), Alexander Fumiyoshi Dori

Dissertations and Theses

This study aims to establish a computational model that will predict the injury response after a sUAS impacts the thorax. A rotary and fixed winged sUAS were chosen for analysis. A vast number of numerical simulations were carried out with varying masses, impact velocities, and impact angles. From the simulation results, the maximum viscous criterion was then calculated. A nonlinear surrogate model was established by setting the impact parameters as independent variables and the viscous criterion as the dependent variable. A correlation analysis showed the impact velocity and angle to significantly influence the results more, when compared to the mass ...


Unmanned Aerial Vehicle Based Structure From Motion Biomass Inventory Estimates, Emily Jane Bedell Dec 2016

Unmanned Aerial Vehicle Based Structure From Motion Biomass Inventory Estimates, Emily Jane Bedell

Dissertations and Theses

Riparian vegetation restoration efforts demand cost effective, accurate, and replicable impact assessments. In this thesis a method is presented using an Unmanned Aerial Vehicle (UAV) equipped with a GoPro digital camera to collect photogrammetric data of a 2.02-acre riparian restoration. A three-dimensional point cloud was created from the photos using Structure from Motion (SfM) techniques. The point cloud was analyzed and compared to traditional, ground-based monitoring techniques. Ground truth data collected using the status-quo approach was collected on 6.3% of the study site and averaged across the entire site to report stem heights in stems/acre in three ...


Development Of 3d Accelerometer Testing System, Mohammed Abbas Soudai Alsaedi Dec 2016

Development Of 3d Accelerometer Testing System, Mohammed Abbas Soudai Alsaedi

Dissertations and Theses

Accelerometers are used in numerous industries including aircrafts and missile navigations systems, rotary machines, and electronic devices such as tablets, cell phones, and cameras. Accelerometers of different purposes and specifications are being produced in large quantities. The large demand for accelerometers forces the need for accelerometer testing methodology that is more convenient and accurate. Inertial Micro-Electromechanical Systems Accelerometer (MEMS) require a series of tests that include physical stimuli. One of the key challenges is the cost associated with testing. Therefore, the accurate prediction of the sensor functions not only reduces the testing time but also more importantly contributes to reducing ...


Development, Characterization, & Implementation Of Phase-Change Material Cold Plates For Hybrid-Electric Vehicle Battery Systems, Kevin Cwiok Dec 2016

Development, Characterization, & Implementation Of Phase-Change Material Cold Plates For Hybrid-Electric Vehicle Battery Systems, Kevin Cwiok

Dissertations and Theses

Due to the regulations on internal combustion engine vehicles, there is a large demand of hybrid and electric vehicles with large battery packs as Energy Storage Systems (ESS) capable of long ranges and decreased emissions. These battery packs output large heat loads during charge-depletion mode and currently require active cooling to keep the batteries within operating conditions. The current systems relied onto achieve this are the air and liquid cooled thermal managements systems. A recent alternative approach to current cooling for ESS thermal management is the use of phase-change materials (PCMs). PCMs regulate the temperature of the ESS by leveraging ...


Application Of Floating Pedal Regenerative Braking For A Rear-Wheel-Drive Parallel-Series Plug-In Hybrid Electric Vehicle With An Automatic Transmission, Dylan Lewis Lewton Dec 2016

Application Of Floating Pedal Regenerative Braking For A Rear-Wheel-Drive Parallel-Series Plug-In Hybrid Electric Vehicle With An Automatic Transmission, Dylan Lewis Lewton

Dissertations and Theses

As the world continues to move further away from our reliance on fossil fuels, hybrid vehicles are becoming ever more popular. Braking is a system on both hybrid and normal vehicles that involves a significant amount of power and energy. A hybrid can recapture some of that energy using regenerative braking. In this thesis, a method is devised to blend hydraulic and regenerative braking in the most effective manner. A MATLAB Simulink model was built to simulate a parallel-series plug-in hybrid electric vehicle. The model allows for the implementation of a regenerative brake controller that utilizes floating pedal regen, custom ...