Digital Commons Network^™

Modeling And Characterization Of Additively Manufactured Barium Titanate Ceramic, Luz Irene Bugarin

Open Access Theses & Dissertations

This dissertation investigates the influence of geometric design on the mechanical properties of BTO structures fabricated via 3D printing. Using finite element modeling (FEM), we simulate mechanical stress responses across a range of architected designs. Results reveal that specific design strategies can significantly enhance performance by promoting favorable stress distributions. This work highlights the critical role of structural design in optimizing functional ceramics and provides a computational framework for the design of next-generation piezoelectric devices.

Technology-Enabled Foreign Object (Fo) Prevention, Christopher Lee Colaw

Open Access Theses & Dissertations

The aviation industry incurs $14 billion per year in cost due to Foreign Object (FO) damage and the prevention and resolution techniques associated with foreign object debris. While aircraft loss, material scrap and rework contribute to that cost impact, a traditional approach to aircraft design and manufacturing which is based on human performance is also a significant driver. Failure modes and effects analysis of human based aircraft manufacturing reveals that two of the largest risks are associated with unknown potential for FO creation and the inability to recall or objectively provide evidence of FO conformity for cases of inquiry, learning, …

Material Extrusion 3d Printing Of Metal Alloy: Material, Methods And Application., Sihan Zhang

Electronic Theses and Dissertations

Material extrusion (MEX) additive manufacturing presents a promising pathway for producing metal components with complex geometries while avoiding the safety hazards associated with loose powder handling in conventional metal additive manufacturing processes. This dissertation investigates the development and optimization of MEX processes for aluminum alloys, addressing critical challenges in feedstock formulation, printing parameter optimization, and post-processing strategies. Three distinct approaches were explored to advance the capabilities of aluminum MEX: filament-based processing of 6061 aluminum, paste-based extrusion of 6061 aluminum, and development of a novel aluminum-magnesium-tin alloy system for space manufacturing applications. The filament-based approach successfully demonstrated the production of 6061 …

Mass Effects On Energy Transfer Paths In Nonlinear Vibrating Systems, Manal Mustafa

Dissertations and Doctoral Documents, University of Nebraska-Lincoln, 2023–

This dissertation examines the role of mass in nonlinear systems, uncovering its role in enabling passive energy redistribution and robust vibration control in both idealized and real-world structures. Focusing on a strongly nonlinear two-degree-of-freedom system, it investigates how changes in mass ratio influence the dynamics of energy transfer, nonlinear normal modes (NNMs), and dissipation behavior.

A number of significant contributions are introduced in this work beginning with the introduction of the frequency-energy-peaks (FE-pks) plot, a novel tool that visualizes how energy flows through the system, revealing transient resonance orbits, internal resonance effects, and effectively capturing the different nonlinear phenomena with …

Shape Memory Behavior In Medium To High Entropy Shape Memory Alloys: Design, Prediction, And Experimental Analysis, Hatim Raji

Theses and Dissertations

This dissertation provides a data-driven system integrating synthetic data generation and machine learning (ML) techniques to create multicomponent SMA compositions with specific transformation temperatures (TTs). Models were trained to represent the nonlinear dependencies influencing martensitic transformation behavior by using elemental, thermodynamic, and process-related aspects. The capacity of the ML models on medium entropy NiTiHfPd and high entropy NiTiHfZrCu systems accuracy was confirmed by experimental validation showing TTs closely matched with model outputs.

A Digital Engineering Framework For Ai-Driven Trade-Off Evaluation And Predictive Component Classification, Alejandro Silva Au

Open Access Theses & Dissertations

This thesis introduces a digital engineering tool designed to help engineers make smarter decisions when choosing actuators. At its core, the system brings together machine learning (specifically XGBoost) and a decision-making method called Multi-Utility Attribute Theory (MUAT). The goal is to support engineers in picking components based on what really matters for their designs, whether that's speed, cost, durability, or any other performance factor. What makes this tool stand out is its user-friendly interface that lets people interact with the system directly. It takes a set of actuator performance data, classifies each one into a relevant use category, and then …

Advancing Real-World Implementation Of The Well Optimized Linear Finder (Wolf) High-Speed Atmospheric Turbulence Compensation Method, Timothy Evan Coon

Theses and Dissertations

This dissertation advances the real-world implementation of the Well Optimized Linear Finder (WOLF) method for high-speed Atmospheric Turbulence Compensation (ATC). Atmospheric turbulence introduces phase aberrations into optical wavefronts and degrades image quality in terrestrial imaging systems. Traditional phase diversity methods are computationally intensive and poorly suited to real-time operation. The WOLF method addresses these limitations through a novel, point-wise formulation of the optical transfer function (OTF) as a structured autocorrelation of the generalized pupil function (GPF). This formulation enables the estimation of phase aberrations at individual spatial coordinates with distributed computational complexity.

The research begins by developing a MATLAB-based simulation …

An Optimization Study Of Multi-Orifice Synthetic Jets, Rhett T. Parry

All Graduate Theses and Dissertations, Fall 2023 to Present

From the mixing of creamer into coffee, to the dynamics of a dust storm, or smoke rising from a chimney—everything is driven by turbulent fluid motion. Experimentalists bring the complex driving mechanism that is turbulence into a laboratory setting to fundamentally understand its behavior in response to certain test parameters. Researchers may choose various drivers, or “actuators”, of fluid motion to start the turbulent regime for their applications. However, in building an entire experimental apparatus, they miss the step of ensuring that an individual driver is performing as best as possible. A common actuator used in experimental studies is a …

Analysis Of Thrust Performance And Noise Generation Of Uam Composite Propellers Fabricated Using Composite-Based Additive Manufacturing, Samiul Alam

All Graduate Theses and Dissertations, Fall 2023 to Present

Urban air mobility (UAM) is an emerging transportation concept that uses lightweight, efficient aircraft for transporting goods and passengers and performing other logistical activities. One of the biggest challenges in developing UAM from a structural perspective is manufacturing strong and reliable propellers that are lightweight and durable. Traditional manufacturing methods for composite propellers are expensive, time-consuming, and difficult to scale. This study explores a new approach using Composite-Based Additive Manufacturing (CBAM) to produce high-performance propellers more efficiently. CBAM allows for the fabrication of strong, lightweight composite propellers using short manufacturing lead times. However, one challenge with this technique is that …

Exploring Methods For Quantifying Uncertainty In Neural Network-Based Turbulence Closures, Cody Grogan

All Graduate Theses and Dissertations, Fall 2023 to Present

Machine Learning (ML) is a very promising field for data-driven modeling of different phenomena. In the field of Computational Fluid Dynamics (CFD), ML is an enticing alternative to traditional methods to improve the accuracy and computational efficiency of simulations. However, many ML models, like Neural Networks, don’t quantify their uncertainty or indicate their confidence in a prediction to those who wish to use them. This is especially important because the use of inaccurate ML predictions in a CFD simulation can greatly impact the validity of a simulation. However, with uncertainty quantification, an ML model can indicate to a modeler the …

Effect Of Moderate Decrease In Contractility On Epithelial Cell-Cell Contacts Under External Stretch, Saika Sharmin

Mechanical & Aerospace Engineering Theses & Dissertations

Epithelial tissues are characterized by extensive cell–cell contacts and often subject to stretch during normal function. Cell-cell contact adhesion strength maintains mechanical continuity from cell to cell. Mechanical forces exerted by cells via actomyosin contractility are known to strengthen cell-cell adhesions to a certain extent. While it is known that a large decrease in contractility causes cell-cell contact rupture due to weakened adhesions, it is unclear how a moderate reduction in contractility affects cell-cell junction stability. Here, we studied how a moderate inhibition of non-muscle myosin II (NMII) affects the integrity of epithelial cell-cell contacts, especially when subject to the …

Towards Improving Computational Modeling Of The Lumbar Spine - Impact Of Material Properties And Laminotomy On Spinal Biomechanics, Isaac K. Kumi

Mechanical & Aerospace Engineering Theses & Dissertations

Spinal ligaments play a crucial role in maintaining the mechanical stability of the lumbar spine. These dense, collagenous tissues not only resist excessive motion but also distribute loads between spinal components to protect neural structures. Traditionally, the mechanical response of ligaments has been modeled using linear elastic assumptions, which treat the tissue as having a constant stiffness regardless of loading history. While this simplifies analysis, it fails to capture the time-dependent behaviors, such as creep, stress relaxation, and hysteresis, that are characteristic of biological tissues.

Viscoelastic modeling may provide a more physiologically accurate representation by incorporating both elastic and viscous …

Inter-Cellular Forces Modulate Cell-Ecm Traction Forces, Zaria Booth

Mechanical & Aerospace Engineering Theses & Dissertations

Epithelial cells are among the most abundant cell types in the human body, making up sheets of epithelial tissues that cover the linings of organs and body cavities. Cellular adhesion and force transmission across epithelial tissues are crucial in maintaining tissue integrity and ensuring proper tissue regeneration. Defects in cellular force transmission have been found in various diseases, including cancer. Force transmission at cell-cell and cell-ECM junctions drive cell survival and development. It has been previously shown that changes in cell-ECM traction directly modulates forces at cell-cell contacts. In this study, we aim to determine the effects of perturbations in …

Is There A More Effective Design For Quadrat To Increase Ease Of Use And Vegetation Density?, Scott M. Burke Jr., Kristen M Bellisario

Discovery Undergraduate Interdisciplinary Research Internship

Quadrats are a special tool in the ecology field that allows the measurement of vegetation density for further data analysis of a habitat. The larger the quadrat cross-sectional area, the better the results of the data, which in turn can make the quadrat hard to carry through field sites. In wildlife corridor research, quadrat surveys provide a quantitative metric for habitat suitability. In this work, we consider the efficiency and ease-of-use benefits for field work in the design of a collapsible version of a quadrat using a House of Quality (standard metric for new design requirements) to assess the customer …

Boiling Heat Transfer Coefficient And Critical Heat Flux On Conical Cylindrical Copper Under Surface Modification, Muhammad Dimyati Nashrullah, Andi Sanata, Imam Solahuddin, Nasrul Ilminnafik, Indro Pranoto, Adhika Widyaparaga

Journal of Mechanical Engineering Science and Technology (JMEST)

This study examined how surface roughness and nanoceramic coating, influences the boiling heat transfer coefficient (BHTC) and critical heat flux (CHF) of a conical cylindrical copper test specimen. Three test specimens exhibiting surface roughness of 0.22 µm, 0.14 µm, and 0.04 µm were analyzed for comparison. Two additional test specimens were treated with nanoceramic coatings utilizing silicon carbide as the base material: one specimen received a single-layer coating and the second was applied with a double-layer coating. The behavior of the bubbles was closely observed with a high-speed camera to deepen the analysis. The experimental results showed that the test …

Characterization Of Bamboo Petung Fiber Reinforced Composites With Environmentally Friendly Enzymes, Rudianto Raharjo, Teguh Dwi Widodo, Redi Bintarto, Fikrul Akbar Alamsyah

Journal of Mechanical Engineering Science and Technology (JMEST)

Natural fiber composites are a good choice for many businesses uses because of their better mechanical properties and are friendly environment. Researchers are currently looking into bamboo petung fiber (BPF) and epoxy composites as alternative to synthetic fibers and products made from petroleum. This study's goal is to improve the overall performance of these composites while reducing the need for non-organic materials. This study used the various concentration of bromelain enzyme in BPF to changes the mechanical and physical properties of epoxy composites made from BPF. Composites were characterized the mechanical properties including tensile strength using tensile tester, impact strength …

Dynamic Analysis And Fatigue Life Evaluation Of Single Herringbone Planetary Gear System With Crack Fault, Dongping Sheng, Jie Yang, Chun Su

Journal of Mechanical Engineering Science and Technology (JMEST)

The herringbone planetary gear transmission is widely used due to its exquisite compact structure, excellent load-bearing capacity, and stable transmission characteristics. However, root crack is one of the most common failure modes of gears. A cracked herringbone planetary gear system is taken as research object. The sun gear with crack fault is studied from the aspect of modal and transient dynamic analysis, and the related results are compared with the healthy gear. Based on the transient dynamic analysis of the herringbone teeth with cracks, a fatigue life evaluation is conducted. Firstly, the results show that no significant difference between the …

Investigation Of The Influence Of Warhead Shape And Type Of Missile Weapon Material Counter-Training Tank Weapons Simulation Approach, Transisma Budiarta, Haris Puspito Buwono, Radhi Nurvian Amrullah

Journal of Mechanical Engineering Science and Technology (JMEST)

This study analyzes the effect of warhead shape and material variations on pressure, temperature, and lift on training missiles using CAD-based simulation methods. The variations of warhead shapes tested include flat, flat radius, and tapered, while the materials used are rubber, ABS, and PE. The simulation results show that the tapered warhead shape with PE material produces the lowest pressure (50.3 MPa) due to more efficient pressure release and low friction properties. Conversely, the Flat shape produces the highest pressure (69.1 MPa) on all materials due to flow stagnation. In terms of temperature, the Flat Radius warhead with PE and …

Characterization Of Curcumin As A Coating Material For Polymer-Free Stents Interms Of Morphology And Release, Ameliyana R.S.P.A. Yani, Muhammad Kusumawan Herliansyah

Journal of Mechanical Engineering Science and Technology (JMEST)

The use of bare metal stents over the long term often leads to the re-narrowing of blood vessels, prompting a shift to drug-eluting stents (DES). However, the use of polymers in DES has been known to trigger inflammation and thrombosis in the arteries. As an alternative, polymer-free drug-eluting stents (PF-DES) have emerged as a safer option. In this study, curcumin was selected as the primary coating material for PFDES using the electrophoretic deposition method. The effects of varying curcumin concentrations (125 µg/ml, 250 µg/ml, and 500 µg/ml) were examined to understand their impact on deposition morphology, coating weight, chemical bonding …

Influence Of Different Nanoparticles On Thermophysical Properties And Wear Resistance Of Corn Oil-Based Cutting Fluid In Mql-Cnc Milling Machining, M Nuril Anwar Habiby, Poppy Puspitasari, Aminnudin Aminnudin, Diki Dwi Pramono, Ahmad Atif Fikri, Mariyam Jameelah Ghazali

Journal of Mechanical Engineering Science and Technology (JMEST)

Vegetable oil-based cutting fluids have emerged as a promising innovation in machining operations, supporting the advancement of sustainable and eco-friendly manufacturing practices. This study delves into the development of a biolubricant derived from corn oil, enriched with 0.15% mass fractions of various nanoparticles, including calcium carbonate (CaCO3), copper oxide (CuO), and multi-walled carbon nanotubes (MWCNT). These nano-cutting fluids were applied through the Minimum Quantity Lubrication (MQL) method during CNC milling of AISI 1045 steel. The investigation focused on evaluating thermophysical properties, including density, thermal conductivity, and dynamic viscosity, as well as tool wear performance. The results demonstrated that CuO nanoparticles …

Toolpath Motion Strategy And Feed Rate In Cnc Milling On Energy Consumption Of Machining Process, Luqman Dwi Saputra, Eko Yudiyanto

Journal of Mechanical Engineering Science and Technology (JMEST)

The use of CNC milling machines to produce components, especially aluminum brackets used for automotive, is one of the advances in the industrial field. The use of CNC milling machines has the advantage of producing processes with speed accuracy, and better workpiece quality than conventional machines. This research investigates energy consumption in the CNC milling process by varying the toolpath motion strategies—Zigzag, Constant Overlap Spiral, Parallel Spiral, and Parallel Spiral Clean Corners—as well as feed rates of 700 mm/min, 800 mm/min, 900 mm/min, and 1000 mm/min. The goal is to find out the best parameters for using energy in the …

Development Of Adjustable Static Test Equipment For Below-Knee Prosthetic Feet: A Case Study, Firmansyah Hafizh Rizal Nurrokhim, Fauzan Raka Mawandi, Puspa Dinda Safitri, Imam Mahmudah, Dwiky Mirnanda, Ndaru Adyono, Wahyu Dwi Lestari

Journal of Mechanical Engineering Science and Technology (JMEST)

The high prevalence of physical disabilities in Indonesia, particularly among the productive-age population, highlights the urgent need for advancements in prosthetic technology. While local fabricators have begun producing prosthetic feet, the lack of standardized testing procedures compromises safety and performance. This study addresses that gap by developing an adjustable static testing device tailored for below-knee prosthetic feet, focusing on keel and heel tests to evaluate mechanical performance. The device includes a jig-fixture platform adjustable to 8° and 15° for heel and keel tests, respectively. It applies a 1230 N load based on AOPA standards and integrates load and displacement sensors …

Tear Resistance Evaluation Of Room Temperature Vulcanizing Silicone Rubber: A Comparative Study, F R. Mawandi, P D. Safitri, D Mirnanda, F H. R. Nurrokhim, Ndaru Adyono, W D. Lestari

Journal of Mechanical Engineering Science and Technology (JMEST)

Room Temperature Vulcanizing (RTV) silicone cures at room conditions, providing tear resistance and flexibility to a wide range of industries. Yet, its mechanical performance improvement continues to be difficult when it is filled and catalyzed. In this work, the tear resistance of three RTV materials—RTV 48, RTV 683, and RTV M4503—is investigated with different talc (2–4 wt.%) and catalyst (40–60 wt.%) formulations. Tear resistance testing per ASTM D624 yielded average and standard deviation values for material consistency determinations. Comparative analysis is also given in the research to ascertain the effect of over-cross-linking on elasticity and structural morphology. RTV 48 experienced …

Effect Of Thickness Of Nanofiber Separator Membrane Pan/Pvdf On Supercapacitor’S Performance, Silvia Nurlaili Agustina, Markus Diantoro, Hartatiek Hartatiek, Nasikhudin Nasikhudin

Journal of Mechanical Engineering Science and Technology (JMEST)

Separators in supercapacitors have an important role as intermediaries for ions that pass during the chargedischarge process and affect the performance of supercapacitors. Therefore, a comprehensive study is needed related to separator characteristics, including morphology, pore size, diameter, functional group, and electrochemical performance of separator membranes from PAN/PVDF composites. The separator membrane was synthesized using the electrospinning method with thickness variation (2, 4, 6, 8, and 10 layers), followed by supercapacitor fabrication with coin cell device. The resulting membrane was then characterized by Scanning Electron Microscope (SEM) and Fourier Transform Infrared (FTIR). For the result of supercapacitor fabrication with coin …

Simulation Of Magnet Thickness And Angle Of Attack On Magnetic Force For Magnetic Turbine Design, Eka Pratama, Wirawan Wirawan

Journal of Mechanical Engineering Science and Technology (JMEST)

Electric motors play a vital role across various industries. As their electricity demand grows, improving efficiency has become a priority. One area of innovation involves the use of magnetic strips for improving performance. This study aims to determine the magnet thickness and the angle of attack position in producing the strongest repulsive force in the magnetic turbine. The study used a simulation using SOLIDWORKS and EMS software, applying neodymium N52 magnets with varying sizes and angles of attack. The results indicate that the most efficient magnetic turbine configuration utilizes rotor and stator magnets with dimensions of Ø10 × 20 mm …

Harnessing The Role Of Carbon Black: A New Frontier For Energy-Density Supercapacitor Electrodes, Ana Yuli Komariyah, Ishmah Luthfiyah, Ida Vaeruza Albadi’Ah, Nasikhudin Nasikhudin, Worawat Meevasana, Markus Diantoro

Journal of Mechanical Engineering Science and Technology (JMEST)

The performance of activated carbon (AC)-based supercapacitor electrodes is often limited by poor electrical conductivity, prompting interest in conductive additives such as carbon black (CB). This study explores the transformative potential of CB as a conductive additive in AC-based supercapacitor electrodes and systematically investigates CB mass loadings of 0%, 5%, 10%, 15%, and 20%, using styrene-butadiene rubber (SBR) as the binder. The findings in this study demonstrate that 10% CB is the optimal loading, offering a balanced performance in terms of structure, morphology, and capacitance. X-ray diffraction (XRD) analysis reveals a distinct structural evolution at 10% CB, characterized by the …

Surface Analysis Of Bacterial Cellulose Membrane Made From Biowaste Added With Zno Nanopowder, Naufal Rizky Amasda, Heru Suryanto, Uun Yanuhar, Aminnudin Aminnudin, Fajar Nusantara, Quota Alief Sias

Journal of Mechanical Engineering Science and Technology (JMEST)

Utilization of pineapple biowaste is important to increase the value added to biowaste and solve the environmental problem. So, the study objective is to synthesize membranes of bacterial cellulose made from pineapple biowaste and characterize the surface morphology and porosity of the membrane after being added with ZnO nanopowder. The study starts with extracting biowaste as a bacterial cellulose culture medium for the fermentation process. The obtained pellicle was crushed and homogenized with the added ZnO nanopowder in the presence of ultrasonic waves. The membrane is dried in the oven. The membrane morphology was monitored using scanning electron microscope and …

Predicting Leakage From Nuclear Material Containers At Los Alamos National Laboratory Through Drop Testing, Leak Testing, Finite Element Analysis And Digital Image Correlation, Jude M. Oka, Yu-Lin Shen, Osman Anderoglu, Pankaj Kumar, Rajendra Vaidya

Mechanical Engineering ETDs

Los Alamos National Laboratory (LANL) relies on containment vessels to safely manage special nuclear material. These containers are subject to rigorous testing—such as drop, fire, and water ingress testing—to ensure integrity under adverse conditions. While elastomer-based seals are well studied, metal-to-metal sealing mechanisms remain under investigation, particularly under dynamic loading. This research focuses on the relationship between container mating surfaces and impact loading through drop testing. Finite Element Analysis (FEA) models were developed and validated using Digital Image Correlation (DIC) to measure strain during impact. Drop tests at varying heights showed strong correlation between FEA and DIC results, confirming the …

Networked Systems: Synchronization, Decomposition And Transient Dynamics, Amirhossein Nazerian

Mechanical Engineering ETDs

This dissertation investigates synchronization, transient dynamics, control, and signal amplification in networked dynamical systems. First, it examines complete and cluster synchronization, including cases with large parametric mismatches, in both natural (e.g., brain networks, fireflies) and technological systems (e.g., power grids, robotics). Second, it studies transient dynamics in consensus processes, designing synchronization strategies that link reactivity, contraction theory, and Lyapunov exponents. Third, it addresses the computational limits of Model Predictive Control (MPC) for large networks by introducing an algebraic decomposition method that enables parallel online computation of smaller subproblems, enhancing MPC performance under hardware constraints. Finally, it analyzes the structural role …

Instability Analysis In Cylindrical Thin Film–Compliant Core Structures: Numerical Simulations And Effects Of Inelastic Deformation, Md Al Rifat Anan

Mechanical Engineering ETDs

When a thin film bonded to a thick compliant substrate is subject to in-plane compression, wrinkles can develop if the critical state for instability is reached. In various applications the film/substrate system may also take the form of cylindrical fibers, where an axial compressive loading can trigger axisymmetric wrinkles. A straightforward computational approach to simulate such wrinkling behavior is needed for material design, to either prevent wrinkling or to exploit its benefits for flexible device applications. In this work a comprehensive numerical study is undertaken by employing the finite element method. The embedded imperfection approach used previously for planar structures …