Mechanical Engineering Commons^™

Boiling Crisis Is A Consequence Of Thermal Runaway In The Substrate Due To Degradation Of Nucleate Boiling Heat Transfer, Manohar Bongarala, Justin A. Weibel, Suresh V. Garimella

CTRC Research Publications

Chaotic bubble interactions during vigorous boiling have foiled attempts at an accurate mechanistic understanding of this important industrial transport process. Prediction of the boiling crisis (dryout) that occurs due to the spontaneous merger of bubbles into an insulating vapor film at critical heat flux remains an unsolved challenge. This work diagnoses the dryout process using synchronized high-resolution spatiotemporal heat flux and phase data, obtained via through-substrate infrared and visual inspection. We examine prevailing theories for the boiling crisis and provide evidence to rule out all but one. The boiling crisis is found to be a consequence of a peak in …

The Shoulder Effect In The Stagnation Zone For Temperature-Controlled Jet Impingement Transition Boiling Of Submerged Dielectric Fluid, Tyler P. Stamps, Justin A. Weibel

CTRC Research Publications

Two-phase jet impingement is capable of high heat transfer coefficients and high boiling critical heat flux (CHF) limits, making it a suitable technology for electronics immersion cooling applications. Previous studies have focused on the heat-flux-controlled nucleate boiling performance of an impingement jet up to the CHF. Exploration of other boiling regimes that occur under temperature-controlled surfaces is of equal fundamental importance. It has been shown for free jets that a high and consistent heat flux can be dissipated over a wide range of surface superheats in the transition boiling regime when the surface is temperature-controlled. This so-called “shoulder effect”, or …

Multiphysics Simulation Of Biochar Adsorption Rates, Joseph Salerno

Graduate Theses & Non-Theses

An accepted carbon capture and sequestration (CCS) method to remove carbon dioxide from the atmosphere is via adsorption onto biochar. While the characteristics of the char are important and greatly impact the adsorption of CO2 molecules, the conditions in which the adsorption occurs are equally critical. Factors such as char particle size and quantity, environmental temperature and pressure, as well as outside driving mechanisms such as vibration frequency, driving force, and flow rates play an impactful role on how the char adsorbs CO2 particles. These factors and their effects will be studied in multiphysics simulations performed using methods that work …

Natural Fiber Reinforced Composites For Sustainable Additive Manufacturing., Athira Nair Surendran

Electronic Theses and Dissertations

Carbon fiber is widely known for its exceptional strength, making it a sought-after material in composite manufacturing, especially with thermosets and thermoplastics. Its major applications span aerospace, wind turbines, sports equipment, automotive interior and exterior parts, robotics and medical equipment. Recently, carbon fiber filament manufacturing has gained attention due to the availability of desktop 3D printers and the versatility and customizability that comes with the realm of 3D printing. Commercial carbon fiber production, primarily from polyacrylonitrile (PAN), is energy-intensive and derived from crude oil, contributing to significant environmental impacts and poor recyclability. Alternatively, lignocellulosic natural fibers present a possible sustainable …

Development Of A High-Throughput Methodology For Vibration-Based Fatigue Tests, Brandon Alexander Furman

All Graduate Theses and Dissertations, Fall 2023 to Present

Global efforts towards the development of additively manufactured materials, biomaterials, metamaterials, self-healing materials, and composites have reached a staggering pace. With new materials being developed on a near-daily basis, it is more important than ever to be able to quickly and precisely quantify their mechanical performance. However, one of the most important mechanical properties, fatigue life, is notoriously time consuming to measure. Consequently, fatigue parameters are often calculated based on small sample sizes, resulting in high uncertainty of the measured parameters. In this dissertation a high-throughput approach to fatigue measurements is developed. This technique allows for multiple samples to accumulate …

Experimental And Computational Investigation Of Green Laser Propagation Through Turbulent Medium In A Water Tank, Richard Owusu Adansi

Open Access Theses & Dissertations

Turbulence medium poses significant challenges to the propagation of laser beams, impacting applications such as free-space optical communication, remote sensing, and laser weapons systems. Therefore, comprehending and mitigating turbulence effects are vital for enhancing the performance of these systems. Analysis of a strong turbulence impact on electromagnetic wave propagation requires extensive knowledge of the Earth's atmospheric and Oceanic phenomena and Maxwell's electromagnetic theory of light as a propagating wave of electric and magnetic fields. Optical systems' propagation often encounters Strong Turbulence, causing interference and diffraction. Nonetheless, light propagation through randomly fluctuating media has been an exciting and active area of …

Hierarchy Of Exchange-Correlation Functionals In Computing Lattice Thermal Conductivities Of Rocksalt And Zinc-Blende Semiconductors, Jiacheng Wei, Zhonghao Xia, Yi Xia, Jiangang He

Mechanical and Materials Engineering Faculty Publications and Presentations

Lattice thermal conductivity (𝜅L) is a crucial characteristic of crystalline solids with significant implications for thermal management, energy conversion, and thermal barrier coating. The advancement of computational tools based on density functional theory (DFT) has enabled the effective utilization of phonon quasiparticle-based approaches to unravel the underlying physics of various crystalline systems. While the higher order of anharmonicity is commonly used for explaining extraordinary heat transfer behaviors in crystals, the impact of exchange-correlation (XC) functionals in DFT on describing anharmonicity has been largely overlooked. The XC functional is essential for determining the accuracy of DFT in describing interactions among electrons/ions …

Transient Heat Transfer To Rolling Or Sliding Drops On Inclined Heated Superhydrophobic Surfaces, Joseph Furner, Daniel Maynes, Brian D. Iverson, Julie Crockett

Faculty Publications

The thermal transport to drops that roll or slide down heated superhydrophobic surfaces is explored. High-speed infrared imaging is performed to provide time-resolved measurement of the heat transfer to the drop. Data are obtained for drops moving along smooth hydrophobic and structured superhydrophobic surfaces. Both post and rib style structures with surface solid fractions ranging from 0.06 to 1.0 are considered. The inclination angle of the surfaces was varied from 10 deg to 25 deg, and the drop volume was varied from 12 to 40 µL. The measurements reveal that the drop speed is a strong function of both the …

Trade-Offs In Lighting For Dic Strain Measurements In Vibration-Based Fatigue Testing, Jacob R. Rigby

All Graduate Theses and Dissertations, Fall 2023 to Present

Vibration based fatigue testing offers a fast and efficient method for determining the breaking point of a material. This method often uses a device, called a strain gage, to measure the deformation of a test sample at a single spot on the test sample. However, these strain gages often break before testing is complete. To overcome this premature break, a laser vibrometer is often used to measure the amount of movement or the speed of the test sample throughout the vibration test. The deformation measured by the strain gage is compared against the amount of movement or velocity of the …

Smart Automatic Modal Hammer Predictor–Corrector Approach For Accurate Excitation Of Dynamical Systems, Mohammad Nasr

Department of Mechanical and Materials Engineering: Dissertations, Theses, and Student Research

This research introduces an innovative solution that revolutionizes the study of linear and nonlinear dynamical systems—a smart automatic modal hammer. With its affordability and intelligent capabilities, this automatic modal hammer becomes an invaluable tool for research and industry, enabling repeatable strikes with precise force control. This system's significance becomes particularly evident when studying nonlinear systems, which heavily rely on the excitation level for their dynamics. By offering a cost-effective design this proposed system proves to be robust in accelerating research on nonlinear dynamics, providing researchers with an efficient and accessible means to delve deeper into these complex systems. The proposed …

Ultrasonic Nondestructive Quantification Of Case Depth In Railroad Bearing Components, Trevor K. Adelung

Department of Mechanical and Materials Engineering: Dissertations, Theses, and Student Research

While in service, railroad bearings must withstand large loads to ensure smooth operation. These large loads can lead to failure due to rolling contact fatigue (RCF), for which small cracks initiate just beneath the surface of the components. As a preventative measure, bearings are manufactured with a hardened surface layer called the effective case depth (ECD). Current methods in industry use destructive hardness testing to quantify the ECD. While accurate, this method is costly and time consuming. Ultrasonic nondestructive testing would provide a more efficient and cost-effective method to determine ECD. In this thesis, diffuse ultrasonic shear backscatter was used …

Studies Of Exotic Electronic, Optical, And Electrochemical Properties In Nanoparticle Assembly And Graphene, Jay Min Lim

Department of Mechanical and Materials Engineering: Dissertations, Theses, and Student Research

It is well known that exotic properties and phenomena emerge as structural dimensions shrink to nanoscales. We self-assembled one-dimensional chains of gold nanoparticles in solution and quantified the growth process by monitoring the redshift of localized surface plasmon resonance (LSPR). Curiously, the redshift stopped while the chains continued to rearrange as manifested by gradual reduction in the LSPR peak. Using electromagnetic simulations, we quantitatively explained the phenomena as a rapid “addition-polymerization” followed by a sharp transition to “condensation-process.” Next, recognizing the significant electric field enhancement in the interparticle gap, a photoluminescent-active Eu³⁺ ion was used to probe Surface-Enhanced Photoluminescence …

Understanding The Microstructure And Tribological Performance Of Cocrfeni-Based High Entropy Alloys, Ali Azarmi

All Theses

Due to their higher wear resistance compared to conventional alloys, high entropy alloys (HEAs) are now being considered as candidates for parts undergoing sliding contact during their lifetimes. While the engineering field has built some knowledge related to the performance of selected high entropy alloys, such as the CoCrFeNi alloy, more research is needed to determine if (how) expansions from four to five principal alloying elements alter the performance compared to the initial alloy. In this study, we started this research effort by investigating the relative performance of CoCrFeNiMn and CoCrFeNiTi with respect to CoCrFeNi. The two primary alloying elements …

Predicting The Ductility Of Tungsten Based Bcc Refractory High Entropy Alloys: A Computational Science Driven Study, Akshay Korpe

All Theses

Bcc refractory high entropy alloys (HEAs) are a relatively new category of metallic alloys that promise excellent irradiation resistance and strength retention at high temperatures but exhibit brittle behavior at room temperatures limiting their formability. Understanding the deformation mechanisms and predicting their ductility at room temperature is a topic of interest in contemporary research.

In this work, multiple independent ductility criteria for quantifying the ductility of these HEAs were studied, calculated and compared using Density Functional Theory (DFT) calculations and continuum mechanics frameworks. These ductility parameters were calculated for various W-Ta-Cr-V alloys and the trends were analyzed for each criteria …

Developing An Assessment Tool For Ideation Effectiveness: A Survey-Based Approach For The Shah’S Method Of Design Space Exploration, Venkat Jaya Deep Jakka

All Theses

The research is focused on creativity in engineering design. The goal is to understand if creativity in engineering design can be assessed using a less resource-intensive approach, specifically a survey, compared to design exercises. The survey builds on the metrics established by Shah and colleagues. The four metrics are Novelty, Quality, Variety and Quantity. The metrics are measured with the help of a design activity that is deployed to the participants. These metrics have been used in comparative analysis to assess treatments such as new design methods and personality types. However, the downside of the metrics is that they require …

Modeling, Simulation, And Experimental Testing Of A Single-Legged Hopper, John Anthony Bennett

Master's Theses

Legged robots are well-suited for navigating unstructured terrain due to their ability to perform agile dynamic motions. Building on the efforts of Cal Poly's Legged Robotics Group, this project focuses on achieving stable forward hopping with a single legged robot.

A comprehensive model of leg hopping is formulated, with leg dynamics during flight and stance phases derived using Euler-Lagrange equations. During the stance phase, a spring-mass system models the leg-ground interaction. The touchdown and lift-off conditions are formulated mathematically, and state mappings between phases are determined via momentum conservation. A two-phase hybrid controller is designed, incorporating trajectory planning during flight …

Natural Language Processing For Automated Sysml Diagram Generation, Joshua Andre Ontiveros

Theses and Dissertations

This thesis explores the applications of natural language processing (NLP) techniques in model-based system engineering (MBSE) to help generate System Modeling Language (SysML) diagrams. MBSE is a method that aids in enhancing traditional engineering practices by modeling to help improve understanding and communication in systems development. SysML, one of the modeling languages for MBSE, helps represent a system's architecture, behavior, and information flow. Translating systems requirements and specifications into SysML models can be time-consuming and can lead to errors when created manually. Automating the creation of SysML diagrams from textual descriptions with the help of NLP techniques can aid in …

Dynamic Modeling Of A Nuclear Integrated Energy System With Thermal Energy Storage And Hydrogen Production, Seth J. Dana

All Graduate Theses and Dissertations, Fall 2023 to Present

Historically, nuclear reactors have used water for cooling and moderating the nuclear reaction within the core. Advanced generation IV nuclear reactors currently under development are designed with different coolants which enable operation at higher temperatures. A higher operating temperature makes nuclear power suitable for co-located hydrogen production via high temperature electrolysis. Natrium, an advanced reactor design by TerraPower and GE Hitachi, combines a sodium fast reactor with molten salt thermal energy storage. The work presented in this thesis models and analyzes three Natrium systems which integrate hydrogen production with the Natrium nuclear power plant. The first two configurations focus on …

Selective Bacterial Biofilm Removal Using Image-Guided Detection And Cold Atmospheric Pressure Plasma, Michael Okebiorun

Boise State University Theses and Dissertations

This dissertation explores the use of cold atmospheric pressure plasma (CAP) technology in eradicating bacterial biofilms from tissue surfaces, using Ps. fluorescens on chicken tissue to model human chronic wounds. It introduces a novel image-guided technique for precise biofilm removal, employing trypan blue staining coupled with advanced computer vision analysis, enhancing the CAP treatment's precision and efficacy. The study demonstrates the CAP device's ability to effectively disrupt biofilms through a non-thermal mechanism, based on its electrical characteristics and operational parameters. The success of the treatment is evident in the significant reduction of biofilm thickness of 49 -185 µm, with the …

Advancements In Aerial Vehicle Platforms: A Guide For Design, Validation, And Implementation Of 3d Printed Drones, Alan Salvador Urteaga

Theses and Dissertations

Additive manufacturing methods have revolutionized the way products are designed and developed through a product's entire design life cycle. This is in part correlated with the nature of additive manufacturing methods that differentiate them from traditional methods. Some of the benefits of additive manufacturing methods include customizability, rapid prototyping, the production of complex design geometry, and embedded assembly manufacturing. Unmanned aerial vehicles have been on the rise for various military, commercial, or personal applications. The focus of this study is to provide detailed instructions on how to engineer a viable drone design that is impact-resistant, modular, and customizable. This study …

In Situ Shear Exfoliation Of Layered Materials And Fabrication Of Multifunctional Composites, Md Abdur Rahman Bin Abdus Salam

Theses and Dissertations

To harness the extraordinary properties of 2D nanomaterials across a range of applications, including but not limited to device fabrication (such as sensors and transistors), energy storage and conversion systems (like batteries and solar cells), as well as biomedical applications (such as drug delivery and tissue engineering), it is imperative to achieve proper synthesis to single-layer form from bulk material, ensuring defect-free synthesis. Recognizing the criticality of defect-free synthesis and high yield for nanocomposite production, our focus centered on developing a facile, contamination-free, single-step, in situ shear exfoliation process for bulk materials (such as graphene, hBN, coal) within elastomers, which …

Feature Extraction From Vibration Signature Acquired From Railroad Bearing Onboard Condition Monitoring Sensor Modules, Kevin Quaye

Theses and Dissertations

The University Transportation Center for Railway Safety (UTCRS) has designed an onboard monitoring system that tracks vibration waveforms over time, to obtain a direct and more accurate indicator of bearing health. The data collected by these sensors is used for vibrational analyses of the bearings. The speed of the bearing is a fundamental parameter needed to carry out the analysis. GPS data can be used to determine bearing speed if available; however, due to size, cost and power constraints GPS is typically not available at the sensor location. This means that analysis must be delayed until the data is uploaded …

Bridging Human Emotion And Autonomous Vehicle Control: Reinforcement Learning Enhancements In The Carla Simulator, Timothy Marion Jude Lyons

Theses and Dissertations

Autonomous vehicles are a key component for an evolution in transportation as they may lead to increased safety and productivity. As autonomous vehicles advance industries will look to further increase customer satisfaction through personalized experiences for autonomous vehicle passengers. Reinforcement learning may be the key to success for autonomous vehicles. The development of autonomous vehicles, utilizing reinforcement learning, which consider the emotions of the passenger, will be a breakthrough for the automotive industry. This thesis presents a unique approach to autonomous vehicles developed with reinforcement learning which consider the human emotions of the passenger. It is a stepping stone to …

Attachment Of 2d Nanomaterials Onto 1d Nanofibers For Separation And Sensing Applications, Elmmer A. Vera Alvarado

Theses and Dissertations

Advancing materials for water desalination and sensing is essential for tackling global issues related to clean water and efficient energy systems. This thesis explores the application of 2D nanomaterials, specifically graphene, integrated onto 1D poly(vinylidene fluoride) (PVDF) nanofibers to enhance their effectiveness in these areas. Utilizing innovative techniques such as Forcespinning® and plasma treatment, PVDF nanofibers were strengthened with graphene and conductive polymers like poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT: PSS). The research involved thorough assessments using direct contact membrane distillation (DCMD) systems, oil-water separation tests, and various mechanical and electromechanical evaluations. Heat-pressed membranes consistently delivered a flux of 0.33 kg/m²/hr and …

Heat Treatment Post-Processing For The Improved Mechanical Properties Of Scalmalloy® Processed Via Directed Energy Deposition, Rachel Boillat-Newport, Sriram Praneeth Isanaka, Frank Liou

Mechanical and Aerospace Engineering Faculty Research & Creative Works

As high-strength aluminum alloys present several processability issues with additive manufacturing (AM), Scalmalloy®, an Al-Mg-Sc-Zr-based alloy, has been developed. This alloy is age-hardenable, allowing it to precipitate out a strengthening precipitate phase, Al3(Sc,Zr). The manufacturer recommends a single-stage aging treatment at 325 °C for 4 h; however, the majority of the literature studies utilize a powder bed processing known as selective laser melting (SLM) over powder-fed processing directed energy deposition (DED). This study addresses the lack of information on heat treatments for DED fabrication by exploring the application of artificial aging temperatures of 300–400 °C for 2, 4, and 6 …

Smart Zoning Control For Air Conditioning Systems, Octavio Gomes Diaz

Mechanical Engineering Theses

Nearly 45% of the energy consumed in residential buildings goes for Heating, Ventilation, and Air Conditioning (HVAC). Typical HVAC systems are mostly controlled by one thermostat that is usually located in the living room. This means that the HVAC system is running without consideration of the thermal conditions in the other rooms (zones), which might be colder (or warmer). Colder zones in the summer indicate that a lot of energy is wasted, and warmer zones mean that the HVAC system can’t produce a good comfort level. Therefore, zoning was introduced into relatively recent HVAC systems. Zoning in HVAC systems uses …

Fundamental Study Of Nonlinear Electrophoresis, Joseph Armakan Bentor

All Dissertations

Classical electrophoretic theory describes the linear response of particles suspended in Newtonian fluids under weak electric fields. When the electric field exceeds this weak limit, a nonlinear response arises due to non-uniform surface conduction over the curved particles. This nonlinear behavior introduces dependencies on fluid and particle properties not considered in the classical theory, offering potential advantages for microfluidic particle manipulation. While this phenomenon has been extensively studied theoretically and numerically in Newtonian fluids, experimental investigations have been relatively limited.

Fluid rheology can significantly alter particle dynamics under applied electric fields. Rheological properties like shear-thinning and elasticity which are not …

Linear And Nonlinear Topology Optimization With Morphing Beam Networks, Andrew S. Montalbano

All Dissertations

Topology optimization (TO) is an engineering design discipline dedicated to optimizing material distribution within a given domain. In traditional gradient-based topology optimization, the solid domain is discretized into small volumetric elements. Using finite element analysis (FEA) of the structure, the gradient of the objective function with respect to the design variables (the pseudo densities) is computed, and these design variables are updated iteratively until convergence is achieved. Although gradient-based TO methods are well-established, sensitivity analyses of objective functions and constraints can be both mathematically complex and computationally intensive. The nonconvex nature of most TO problems often complicates efficient convergence. Furthermore, …

Hybrid Physics-Infused Machine Learning Framework For Fault Diagnostics And Prognostics In Cyber-Physical System Of Diesel Engine, Shubhendu Kumar Singh

All Dissertations

Fault diagnosis is required to ensure the safe operation of various equipment and enables real-time monitoring of associated components. As a result, the demand for new cognitive fault diagnosis algorithms is the need of the hour. Existing deep learning algorithms can detect, classify, and isolate faults. Still, most depend solely on data availability and do not incorporate the system's underlying physics into their prediction. Therefore, the results generated by these fault-detecting algorithms sometimes need to make more sense and deliver when tested in actual operating conditions.

Similar to diagnosis, the fault prognosis of diesel engines is paramount in numerous industries. …

Reactive Processing Of Hf-Nb-Ti-Ta Melts Into A B4c/C Packed Bed, Laura Leticia Sandoval

Open Access Theses & Dissertations

The reactivity of liquid Hf-Nb-Ti-Ta alloy in B4C/C packed bed to form boride-carbide precipitates for ultra-high temperature ceramics was investigated at 2800 K. The objectives were to predict the thermodynamic phases formed and verify them with microstructural characterization. A pseudo-isopiestic technique was used to significantly lower the oxygen potential as the liquid Hf alloy infused and reacted into a B4C packed bed within a graphite enclosure. The technique had a low temperature region (at 1300 K) to control the oxygen potential with a Y-Al/Y2O3-Al2O3/carbide mixture as a liquid Hf alloy at 2800 K and reacted with B4C/C. In addition, any …