Mechanical Engineering Commons^™

Additive Manufacturing Of Stretchable Strain Sensors: Fabrication, Optimization And Application, John Nady Shihat Bastawrous

Theses and Dissertations

In this project, a novel strain sensor design is fabricated employing different additive manufacturing techniques. The spring sensor's primary material is PLA-Like resin with a nanocomposite encapsulation layer as the functional material. The main principle of Straining the sensors results in a change in resistivity as the distances among the conductive carbon particles change according to the strain applied.

Sensor fabrication consists of two parts: spring manufacturing and development of nanocomposite encapsulation The nanocomposite matrix is developed through the dispersion of Graphene and Carbon nanotubes in Thermoplastic Polyurethane through sonication and magnetic hotplate stirring. While the spring itself is manufactured …

Understanding The Effectiveness Between Modern Technologies And Traditional Training Methods Of E-Learning On An Individual’S Learning Curve, Content Retention, And Satisfaction, Andressa Camacho Ortiz

Theses and Dissertations

E-learning has become a widespread and valuable tool for skill development. After the COVID-19 pandemic, the necessity and adaptability of this method increased drastically. Hence, numerous studies focused on understanding the effectiveness of this method. The academic literature highlights the need to explore alternative solutions that can increase a learner’s content retention and satisfaction when learning remotely. Modern technologies can be a great solution for this need with the correct application and development. This thesis analyzes the effects of technology on content retention, satisfaction, and learning curve through the following technologies: online platform, virtual reality (VR), and hologram display. A …

Convexity Applications In Single And Multi-Agent Control, Olli Nikodeemus Jansson

All Graduate Theses and Dissertations

The focus of this dissertation is in the application of convexity for control problems; specifically, single-agent problems with linear or nonlinear dynamics and multi-agent problems with linear dynamics. A mixture of convex and non-convex constraints for optimal control problems is also considered. The main contributions of this dissertation include: 1) a convexification of single-agent problems with linear dynamics and annular control constraint, 2) a technique for controlling bounded nonlinear single-agent systems, and 3) a technique for solving multi-agent pursuit-evasion games with linear dynamics and convex control and state constraints. The first result shows that for annularly constrained linear systems, controllability …

Experimental And Numerical Studies Of Slurry-Based Coextrusion Deposition Of Continuous Carbon Fiber Micro-Batteries To Additively Manufacture 3d Structural Battery Composites, Aditya R. Thakur, Xiangyang Dong

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Carbon Fiber Structural Battery Composites Have Recently Attracted Growing Interests Due to their Potentials of Simultaneously Carrying Mechanical Loads and Storing Electrical Energy for Lightweight Application. in This Study, We Present a Slurry-Based Coextrusion Deposition Method to Additively Manufacture 3D Structural Battery Composites from Carbon Fiber Micro-Batteries. Cathode Slurry is Coextruded Together with Solid Polymer Electrolyte-Coated Carbon Fibers in a Single Deposition. a Network of Carbon Fiber Micro-Batteries is Achieved within the Fabricated Structural Battery Composites. Electrochemical Tests Show a Stable Charge-Discharge Performance Up to 100 Cycles. the Rheological Behavior of the Cathode Slurry is Found to Govern the Coextrusion …

Copyright, 3d Printing, And The Value Of Open Vetted 3d Oer, Wilhelmina Randtke, Lee Bareford, John Schlipp

All Things Open

Libraries are protected from copyright lawsuits when patrons make copies, as long as signage is posted and patrons make the copies themselves. But, unlike copying or printing in libraries, self-service 3D printing in libraries is unrealistic. 3D prints take hours to finish, and troubleshooting 3D printing problems takes skill and experience. Meanwhile, the top websites for finding CAD designs to download and 3D print are rampant with copyright infringement. This presentation provides an overview of the status of copyright for 3D printing, covers the tech of why 3D printing is different from printing and copying on paper, and advocates for …

Microscale Modelling Of Lightning Damage In Fibre-Reinforced Composites, Scott L. J. Millen, Juhyeong Lee

Mechanical and Aerospace Engineering Faculty Publications

In this work, three-dimensional (3D) finite element simulations were undertaken to study the effects of lightning strikes on the microscale behaviour of continuous fibre-reinforced composite materials and to predict and understand complex lightning damage mechanisms. This approach is different from the conventional mesoscale or macroscale level of analysis, that predicts the overall lightning damage in composite laminates, thus providing better understanding of lightning-induced thermo-mechanical damage at a fundamental level. Micromechanical representative volume element (RVE) models of a UD composite laminate were created with circular carbon fibres randomly distributed in an epoxy matrix. The effects of various grounding conditions (one-, two-, …

Mechanical Metamaterials, Brent A. Peluso, Oliver T. Parker

Mechanical Engineering

Mechanical metamaterials are an emerging design strategy aimed at tailoring lattice structures to achieve specific properties such as negative Poisson’s ratios and guiding wave propagation. These metamaterials have received increasing attention from various application domains, including medical devices, aerospace, automobile, and infrastructure. The scope of this project is to vary a single lattice parameter and quantify its effect on the structural properties of the given 3D lattice.

Measured Spectral, Directional Radiative Behavior Of Corrugated Surfaces, Kyle S. Meaker, Ehsan Modfidipour, Matthew R. Jones, Brian D. Iverson

Faculty Publications

Spacecraft thermal control is entirely reliant upon radiative heat transfer with its surroundings for tem- perature regulation. Current methods are often static in nature and do not provide dynamic control of radiative heat transfer. As a result, modern spacecraft thermal control systems are typically ‘cold-biased’ with radiators that are larger than necessary for many operating conditions. Deploying a variable radiator as a thermal control technique in which the projected surface area can be adjusted to provide the appro- priate heat loss for a given condition can reduce unnecessary heat rejection and reduce power require- ments. However, the radiative behavior of …

Creativity, Craftsmanship, And Connection: Large-Format Sculpture Design, Jacqueline L. Puga, Gordon Hoople

The STEAM Journal

Artistry is a concept that is not usually explored in engineering yet is an invaluable skill that touches everything from product design to systems thinking. This past summer I developed conceptual designs for a large format sculpture that required connecting engineering knowledge with artistic vision. The initial phase required constant inspiration and creativity. The first step was to look at previous sculptures showcased throughout the world, such as at venues like “Burning Man,” to understand the possibilities or limitations of the space provided. Sketching varied and numerous ideas was essential in our design process. Next, we took our favorite ideas …

Biogas Combustion Characteristics In A Concentric Flow Slot Burner: Effects Of Co2 Concentration On Stability And Flame Structure, Maged Kiriakos

Theses and Dissertations

Biogas combustion is affected by the concentration of carbon dioxide. The successful applications of Biogas as a sustainable renewable alternative fuel produced from waste depend on its combustion stability, heat release, and pollution level. The aim of the current study is to apply new combustion technology and study the stability and combustion characteristics of natural gas with different percentages of carbon dioxide from 0 to 40% simulating biogas fuel. The stability characteristics and the temperature profiles of turbulent planar flames at different levels mixture inhomogeneity are investigated and presented in this work. The flames are created in a newly developed …

Changes In The Mechanical Performance Of An Ortho-Planar Spring After Aging Tests, Lucas F. L. Santos, Larry L. Howell, Jose J. R. D’Almeida

Faculty Publications

This paper analyzed an ortho-planar spring (OPS) compliant mechanism and evaluated its mechanical performance after hygrothermal and ultraviolet radiation aging tests. The aging analysis performed here addresses the performance of compliant mechanisms after aging processes which can help inform the design of future compliant mechanisms. ASTM D638 tensile test type I samples were also submitted to aging to serve as a comparison for OPS samples. The samples were submitted to three different kinds of aging conditions, namely water immersion, oil immersion, and ultraviolet radiation. In conclusion, tensile samples showed significant statistical changes in Young's modulus and elongation at break, whereas …

Estimation Of The Response, Power Spectra, And Whirling Patterns Generated From Mud Circulating Along The Annulus During Drilling Procedures: An Alternative Mathematical Representation Via Finite Element Modelling, Eleazar Marquez

Mechanical Engineering Faculty Publications and Presentations

In this study, an alternative mathematical representation of a drill-string is proposed to provide an alternative assessment on BHA dynamic alterations. Lateral vibrations remain the focal point of drill-string breakdowns given their high frequency characterization and ability to deviate perforation trajectories from the subsurface target. In this paper, the proposed model consists of an anisotropic rotor subjected to distinct RPMs, an axial force, and a bidirectional harmonic excitation with specified amplitude and assorted duration to simulate annulus motion generated from the mud fluid. In this regard, Euler-Bernoulli beam theory was adopted to establish a complete MDOF mathematical expression and thus …

Development Of An Improved Mathematical Representation Which Captures The Nonlinear Dynamic Behavior Of A Drill-String Assembly, Eleazar Marquez

Mechanical Engineering Faculty Publications and Presentations

In this study, an improved mathematical representation of a drill-string assembly is developed to provide an alternative assessment on vibration irregularities proliferating downhole due to bit-rock interference. Lateral vibrations receive particular attention due to their high frequency content which alter the dynamic response of the drill-string, instigate casing damage, and impede optimal penetration rates. The response of the drill-string is captured by synthesizing compatible stationary bit excitations, via an auto-regressive digital filter, and implementing Monte Carlo simulation, while the power spectral density function is approximated to elucidate the dynamic characteristics during drilling. Formulating adequate physical parameters for the equation of …

A Probabilistic Analysis In Vibration-Assisted Drilling To Measure Dynamic Behavior During Drilling And Understand Risk Factors, Eleazar Marquez, Samuel Garcia

Mechanical Engineering Faculty Publications and Presentations

In this paper, a mathematical representation is proposed to further understand the dynamic behavior and risk factors associated with vibration-assisted drilling (VAD) technology. The proposed Timoshenko beam model, which characterizes VAD technology, consists of two passive, counter-rotating coaxial rotors operating simultaneously, subjected to a stochastic excitation. In this regard, a finite element technique was incorporated to determine the physical parameters of the governing equation of motion, where the shear and rotary effects, as well as the gyroscopic couples generated perpendicular to the axis of rotation, were accounted for. Further, the relative velocity between the coaxial rotors was accounted in the …

Session 11: Can Machine Learning Predict Particle Deposition At Specific Intranasal Regions Based On Computational Fluid Dynamics Inputs/Outputs And Nasal Geometry Measurements?, Mohammad Mehedi Hasan Akash, Zachary Silfen, Diane Joseph-Mccarthy, Arijit Chakravarty, Saikat Basu

SDSU Data Science Symposium

Along with machine learning modeling, numerical simulations of respiratory airflow and particle transport can be used to improve targeted deposition at the upper respiratory infection site of numerous airborne diseases. Given the need for more patient data from varied demographics, we propose a machine learning-enabled protocol for determining optimal formulation design parameters that may match nasal spray device settings for successful drug delivery. We measured 11 anatomical parameters (including nasopharyngeal volume, nostril heights, and mid-nasal cavity volume) for 10 CT-based nasal geometries representative of the population for this aim. We also ran 160 computational fluid dynamics simulations of drug delivery …

Session 2: The Effect Of Boom Leveling On Spray Dispersion, Travis A. Burgers, Miguel Bustamante, Juan F. Vivanco

SDSU Data Science Symposium

Self-propelled sprayers are commonly used in agriculture to disperse agrichemicals. These sprayers commonly have two boom wings with dozens of nozzles that disperse the chemicals. Automatic boom height systems reduce the variability of agricultural sprayer boom height, which is important to reduce uneven spray dispersion if the boom is not at the target height.

A computational model was created to simulate the spray dispersion under the following conditions: a) one stationary nozzle based on the measured spray pattern from one nozzle, b) one stationary model due to an angled boom, c) superposition of multiple stationary nozzles due an angled boom, …

Membrane-Enhanced Lamina Emergent Torsional Joints For Surrogate Folds, Guimin Chen, Spencer P. Magleby, Larry L. Howell

Faculty Publications

Lamina emergent compliant mechanisms (including origami-adapted compliant mechanisms) are me- chanical devices that can be fabricated from a planar material (a lamina) and have motion that emerges out of the fabrication plane. Lamina emergent compliant mechanisms often exhibit undesirable para- sitic motions due to the planar fabrication constraint. This work introduces a type of lamina emergent torsion (LET) joint that reduces parasitic motions of lamina emergent mechanisms (LEMs), and presents equations for modeling parasitic motion of LET joints. The membrane joint also makes possible one-way joints that can ensure origami-based mechanisms emerge from their flat state (a change point) into …

Symmetric Equations For Evaluating Maximum Torsion Stress Of Rectangular Beams In Compliant Mechanisms, Guimin Chen, Larry L. Howell

Faculty Publications

There are several design equations available for calculating the torsional compliance and the maximum torsion stress of a rectangular cross-section beam, but most depend on the relative magnitude of the two dimensions of the cross-section (i.e.,the thickness and the width). After reviewing the available equations, two thickness-to-width ratio independent equations that are symmetric with respect to the two dimensions are obtained for evaluating the maximum torsion stress

of rectangular cross-section beams. Based on the resulting equations, outside lamina emergent torsional joints are analyzed and some useful design insights are obtained. These equations, together with the previous work on symmetric equations …

Halloysite Reinforced Natural Esters For Energy Applications, Jaime Taha-Tijerina, Karla Aviña, Victoria Padilla-Gainza, Aditya Akundi

Informatics and Engineering Systems Faculty Publications and Presentations

Recently, environmentally friendly and sustainable materials are being developed, searching for biocompatible and efficient materials which could be incorporated into diverse industries and fields. Natural esters are investigated and have emerged as eco-friendly high-performance alternatives to mineral fluids. This research shows the evaluations on thermal transport and tribological properties of halloysite nanotubular structures (HNS) reinforcing natural ester lubricant at various filler fractions (0.01, 0.05, and 0.10 wt.%). Nanolubricant tribotestings were evaluated under two configurations, block-on-ring, and 4-balls, to obtain the coefficient of friction (COF) and wear scar diameter (WSD), respectively. Results indicated improvements, even at merely 0.01 wt.% HNS concentration, …

Launching A 3d Printing Program For Students: Recommendations And Best Practices For Libraries, Wilhelmina Randtke, Lee Bareford

Georgia Library Quarterly

The Georgia Southern University Libraries launched a 3D printing program for students in July 2022. Prior to launch, library employees at two of Georgia Southern University’s campuses investigated options for implementing safe, affordable, and sustainable 3D printing in existing academic libraries without retrofitting costly ventilation systems into existing facilities. This article describes the reasons why the Georgia Southern University Libraries thought that a 3D printing program could fulfill a service need for students across university colleges and departments and outlines some of the challenges, best practices, and unique innovations that the library’s employees experienced throughout the program launch process. The …