Digital Commons Network^™

Measuring And Modeling Grease Degradation, Alan Gurt

LSU Doctoral Dissertations

Lubricating grease is an ideal lubricant for many devices such as roller bearings, journal bearings, slide bearings, gears, and many types of joints due to its simplicity. Once grease is put in place, it can often provide adequate lubrication for extended periods of time without the need for a complex supply system that would generally be needed for oil lubrication. However, during prolonged use, various degradation mechanisms change the physical and chemical properties of grease, possibly leading to inadequate performance and machinery failure.

In order to succinctly quantify the degradation of grease, it is essential to have robust, meaningful test …

Development Of Machine Learning-Based Tool For Prediction Of Long-Term Field Performance Of Asphalt Concrete Overlays In A Hot And Humid Climate, Elise Mansour

LSU Doctoral Dissertations

The performance of pavement plays a critical role in Maintenance, Rehabilitation and Reconstruction (MR&R) for highway agencies. Reliable and accurate estimation of pavement performance can be instrumental in prioritization of the limited resources and funding for highway agencies. The latter requires robust prediction models that can handle large-scale, real-world data and can forecast pavement performance in the long run. Unfortunately, the traditional performance prediction models have raised concerns regarding their efficiency and accuracy. It is because these models were based on a limited number of explanatory variables, were not up-to-date and were designed for forecasting short-term (up to five years) …

Effect Of Workload And Trust On Automation Levels In Human-Robot Collaboration, Abhiram Maddula

LSU Master's Theses

Automation is becoming increasingly common in manufacturing and assembly plants. The future lies in hybrid workspaces where the strengths of humans and robots complement each other, with robots excelling in precision, speed, and strength, and humans excelling in creativity, emotional intelligence, and complex decision-making. Collaborative robots can foster a more efficient and productive work environment by bridging the gap between human and machine capabilities. This study examines how semi-automated and automated modes impact human-robot collaboration, focusing on mental workload, trust, and task performance.

In this experiment, 58 participants performed a primary task alongside a collaborative robot assembling a miniature lamppost …

Gastrointestinal Ischemia In The Horse: Preoperative Detection And Surgical Intervention, Michael P. St. Blanc

LSU Master's Theses

The objective of this study was to evaluate the utility of calprotectin, a protein released by activated leukocytes during inflammation, in the detection of gastrointestinal ischemia in horses with signs of abdominal pain (colic). Additionally, one-layer end-to-end anastomoses of the descending colon were critically evaluated in comparison to two-layer closures. For the calprotectin portion of the study, samples were obtained from ten control horses and nineteen clinical cases assigned to three treatment groups (non-strangulating, strangulating small intestinal, or strangulating large intestinal lesions). Objective data was collected from each patient, and calprotectin concentration in serum and peritoneal fluid was determined using …

Pooled Analysis Of Physical Activity, Sedentary Behavior, And Sleep Among Children From 33 Countries, Kar Hau Chong, Thomas Suesse, Penny L. Cross, Sarah T. Ryan, Eivind Aadland, Oluwayomi Aoko, Ankhmaa Byambaa, Valerie Carson, Jean Philippe Chaput, Hayley Christian, Dylan P. Cliff, Marieke De Craemer, Clarice Maria De Lucena Martins, Christine Delisle Nyström, Catherine E. Draper, Asmaa El Hamdouchi, Alex Antonio Florindo, Hongyan Guan, Amy S. Ha, Najmeh Hamzavi Zarghani, Kylie D. Hesketh, Mohammad Sorowar Hossain, Jajat Jajat, Thanh Kim, Denise Koh, Anna V. Kontsevaya, Nicholas Kuzik, Marja H. Leppänen, Marie Löf, Himangi Lubree, Kim Meredith-Jones, Tawonga W. Mwase-Vuma, Johan Y.Y. Ng, Rachel Novotny

Population and Public Health Science Faculty Publications

Importance: The prevalence estimates of physical activity, sedentary behavior, and sleep (collectively known as movement behaviors) in 3-and 4-year-old children worldwide remains uncertain. Objective: To report the proportion of 3-and 4-year-old children who met the World Health Organization guidelines for physical activity, sedentary behavior, and sleep across 33 countries. Design, Setting, and Participants: Pooled analysis of data from 14 cross-sectional studies (July 2008 to September 2022) identified through systematic reviews and personal networks. Thirty-Three countries of varying income levels across 6 geographical regions. Each study site needed to have at least 40 children aged 3.0 to 4.9 years with valid …

Short Communication: Numerically Simulated Time To Steady State Is Not A Reliable Measure Of Landscape Response Time, Nicole M. Gasparini, Adam M. Forte, Katherine R. Barnhart

Faculty Publications

Quantifying the timescales over which landscapes evolve is critical for understanding past and future environmental change. Computational landscape evolution models are one tool among many that have been used in this pursuit. We compare numerically modeled times to reach steady state for a landscape adjusting to an increase in rock uplift rate. We use three different numerical modeling libraries and explore the impact of time step, grid type, numerical method for solving the erosion equation, and metric for quantifying the time to steady state. We find that modeled time to steady state is impacted by all of these variables. Time …

Euphemism In Ai Discourse As Colonial Harm & Effect: Learnings From Subaltern Puerto Rico, Jacqueline Oquendo

LSU Doctoral Dissertations

Through three integrated studies, this dissertation explores complex human-AI interactions by comparing the perceptions of two groups of U.S. citizens: subaltern Puerto Ricans and stateside Americans’ interactions with ChatGPT. This corpus-assisted Critical Discourse Analysis or CLCDA, triangulated with 1:1 semi-structured interviews, validates scholars’ concerns about the biases inherent in generative AI. Contributing to those concerns, this dissertation reveals that ChatGPT deploys discourse strategies that, when executed, facilitate digital colonialism. Euphemistic language is prominent among its discourse strategies, replacing controversial words, phrases, and topics with more palatable ones. When prompted on events of historical significance, I find that ChatGPT’s discourse obscures …

Assessing The Influence Of Occupancy Factors On Energy Performance In Us Small Office Buildings, Seddigheh Norouziasl, Sorena Vosoughkhosravi, Amirhosein Jafari, Zhihong Pang

Faculty Publications

Office buildings are responsible for about 35% of the total electricity in the US and over 70% of building energy consumption occurs during occupancy periods. Therefore, understanding occupancy behavior is crucial for reducing building energy consumption. However, given the stochastic nature of occupant behavior, identifying which occupancy parameters have the most impact on energy consumption poses a considerable challenge. This study aims to investigate and quantify the impact of various occupancy parameters on the energy performance of a US small-sized office building using an EnergyPlus-based nationwide energy simulation. First, dynamic occupancy schedules are created based on different occupancy parameters using …

Assessing Dimensions Of Thought Disorder With Large Language Models: The Tradeoff Of Accuracy And Consistency, Samuel L. Pugh, Chelsea Chandler, Alex S. Cohen, Catherine Diaz-Asper, Brita Elvevåg, Peter W. Foltz

Faculty Publications

Natural Language Processing (NLP) methods have shown promise for the assessment of formal thought disorder, a hallmark feature of schizophrenia in which disturbances to the structure, organization, or coherence of thought can manifest as disordered or incoherent speech. We investigated the suitability of modern Large Language Models (LLMs - e.g., GPT-3.5, GPT-4, and Llama 3) to predict expert-generated ratings for three dimensions of thought disorder (coherence, content, and tangentiality) assigned to speech samples collected from both patients with a diagnosis of schizophrenia (n = 26) and healthy control participants (n = 25). In addition to (1) evaluating the accuracy of …

In Silico And Functional Analysis Identifies Key Gene Networks And Novel Gene Candidates In Obesity-Linked Human Visceral Fat, Lijin Wang, Pratap Veerabrahma Seshachalam, Ruiming Chua, Hongwen Zhou, Sun Lei, Sujoy Ghosh

Division of Basic Science Faculty Publications

Objective: Visceral adiposity is associated with increased proinflammatory activity, insulin resistance, diabetes risk, and mortality rate. Numerous individual genes have been associated with obesity, but studies investigating gene regulatory networks in human visceral obesity have been lacking. Methods: We analyzed gene regulatory networks in human visceral adipose tissue (VAT) from 48 and 11 Chinese patients with and without obesity, respectively, using gene coexpression and gene regulatory network construction from RNA-sequencing data. We also conducted RNA interference-based functional tests on selected genes for effects on adipocyte differentiation. Results: A scale-free gene coexpression network was constructed from 360 differentially expressed genes between …

Genomic Analysis Of Intracranial And Subcortical Brain Volumes Yields Polygenic Scores Accounting For Variation Across Ancestries, Luis M. García-Marín, Adrian I. Campos, Santiago Diaz-Torres, Jill A. Rabinowitz, Zuriel Ceja, Brittany L. Mitchell, Katrina L. Grasby, Jackson G. Thorp, Ingrid Agartz, Saud Alhusaini, David Ames, Philippe Amouyel, Ole A. Andreassen, Konstantinos Arfanakis, Alejandro Arias-Vasquez, Nicola J. Armstrong, Lavinia Athanasiu, Mark E. Bastin, Alexa S. Beiser, David A. Bennett, Joshua C. Bis, Marco P.M. Boks, Dorret I. Boomsma, Henry Brodaty, Rachel M. Brouwer, Jan K. Buitelaar, Ralph Burkhardt, Wiepke Cahn, Vince D. Calhoun, Owen T. Carmichael, Mallar Chakravarty, Qiang Chen, Christopher R.K. Ching, Sven Cichon

Clinical Research Faculty Publications

Subcortical brain structures are involved in developmental, psychiatric and neurological disorders. Here we performed genome-wide association studies meta-analyses of intracranial and nine subcortical brain volumes (brainstem, caudate nucleus, putamen, hippocampus, globus pallidus, thalamus, nucleus accumbens, amygdala and the ventral diencephalon) in 74,898 participants of European ancestry. We identified 254 independent loci associated with these brain volumes, explaining up to 35% of phenotypic variance. We observed gene expression in specific neural cell types across differentiation time points, including genes involved in intracellular signaling and brain aging-related processes. Polygenic scores for brain volumes showed predictive ability when applied to individuals of diverse …

Studying Geometry Of The Ultraluminous X-Ray Pulsar Swift J0243.6+6124 Using X-Ray And Optical Polarimetry, Juri Poutanen, Sergey S. Tsygankov, Victor Doroshenko, Sofia V. Forsblom, Peter Jenke, Philip Kaaret, Andrei V. Berdyugin, Dmitry Blinov, Vadim Kravtsov, Ioannis Liodakis, Anastasia Tzouvanou, Alessandro Di Marco, Jeremy Heyl, Fabio La Monaca, Alexander A. Mushtukov, George G. Pavlov, Alexander Salganik, Alexandra Veledina, Martin C. Weisskopf, Silvia Zane, Vladislav Loktev, Valery F. Suleimanov, Colleen Wilson-Hodge, Svetlana V. Berdyugina, Masato Kagitani, Vilppu Piirola, Takeshi Sakanoi, Iván Agudo, Lucio A. Antonelli, Matteo Bachetti, Luca Baldini, Wayne H. Baumgartner, Ronaldo Bellazzini

Faculty Publications

Discovery of pulsations from a number of ultra-luminous X-ray (ULX) sources proved that accretion onto neutron stars can produce luminosities exceeding the Eddington limit by several orders of magnitude. The conditions necessary to achieve such high luminosities as well as the exact geometry of the accretion flow in the neutron star vicinity are, however, a matter of debate. The pulse phase-resolved polarization measurements that became possible with the launch of the Imaging X-ray Polarimetry Explorer (IXPE) can be used to determine the pulsar geometry and its orientation relative to the orbital plane. They provide an avenue to test different theoretical …

Underrepresented Minority Faculty In The Usa Face A Double Standard In Promotion And Tenure Decisions, Theodore Masters-Waage, Christiane Spitzmueller, Ebenezer Edema-Sillo, Ally St. Aubin, Michelle Penn-Marshall, Erika Henderson, Peggy Lindner, Cynthia Werner, Tracey Rizzuto, Juan Madera

Faculty Publications

Underrepresented minority (URM) faculty face challenges in many domains of academia, from university admissions to grant applications. We examine whether this translates to promotion and tenure (P&T) decisions. Data from five US universities on 1,571 faculty members’ P&T decisions show that URM faculty received 7% more negative votes and were 44% less likely to receive unanimous votes from P&T committees. A double standard in how scholarly productivity is rewarded is also observed, with below-average h-indexes being judged more harshly for URM faculty than for non-URM faculty. This relationship is amplified for faculty with intersectional backgrounds, especially URM women. The differential …

Combined Toxicity Of Multi-Walled Carbon Nanotubes And Cu2+ On The Growth Of Ryegrass: Effect Of Surface Modification, Dose, And Exposure Time Pattern, Wenwen Xie, Cheng Peng, Weiping Wang, Xiaoyi Chen, Jiaqi Tan, Wei Zhang

Faculty Publications

The escalating release of multi-walled carbon nanotubes (MWCNTs) into the environment has raised concerns due to their potential ecotoxicological impacts. However, their combined phytotoxicity with heavy metals such as copper (Cu) is still unclear. This study investigated the individual and combined toxic effects of MWCNTs (MWCNT, MWCNT-OH, and MWCNT-COOH) and Cu²⁺ on ryegrass (Lolium multiflorum), uniquely considering different addition orders. The results show that Cu severely inhibited the growth of ryegrass while MWCNTs exhibited a hormesis effect on ryegrass. When MWCNT and Cu were combined, the malondialdehyde (MDA) content in ryegrass showed a 32.39% increase at 20 mg/L MWCNT …

The Roles Of Vicarious Trauma Exposure And Perceived Social Support In Codeine Syrup Misuse Among Black Men Living In Prisons, Jardin Dogan-Dixon, Shawndaya S. Thrasher, Shemeka Thorpe, Paris Wheeler, Danelle Stevens-Watkins

Faculty Publications

Using General Strain Theory, this study investigates the effects of vicarious trauma exposure and perceived social support on nonmedical codeine syrup misuse among Black incarcerated men nearing community re-entry. Data were drawn from the Helping Incarcerated Men project, a study examining mental health, substance misuse, and human immunodeficiency virus (HIV) risk behaviors among Black men living in prisons who were within 180 days of release. A total of 200 Black men self-reported demographics (i.e., age and length of incarceration after age 18), vicarious trauma exposure (e.g., ever witnessing an assault with a weapon and a sudden accidental death), perceived social …

Deephive: A Reinforcement Learning Approach For Automated Discovery Of Swarm-Based Optimization Policies, Eloghosa Ikponmwoba, Opeoluwa Owoyele

Faculty Publications

We present an approach for designing swarm-based optimizers for the global optimization of expensive black-box functions. In the proposed approach, the problem of finding efficient optimizers is framed as a reinforcement learning problem, where the goal is to find optimization policies that require a few function evaluations to converge to the global optimum. The state of each particle within the swarm is defined as its current position and function value within a design space, and the particles learn to take favorable actions that maximize the reward, which is based on the final value of the objective function. The proposed approach …

Research Gaps And Priorities For Quantitative Microbial Risk Assessment (Qmra), Kerry A. Hamilton, Joanna Ciol Harrison, Jade Mitchell, Mark Weir, Marc Verhougstraete, Charles N. Haas, A. Pouyan Nejadhashemi, Julie Libarkin, Tiong Gim Aw, Kyle Bibby, Aaron Bivins, Joe Brown, Kara Dean, Gwyneth Dunbar, Joseph N.S. Eisenberg, Monica Emelko, Daniel Gerrity, Patrick L. Gurian, Emma Hartnett, Michael Jahne, Rachael M. Jones, Timothy R. Julian, Hongwan Li, Yanbin Li, Jacqueline Mac Donald Gibson, Gertjan Medema, J. Scott Meschke, Alexis Mraz, Heather Murphy, David Oryang, Emmanuel De Graft Johnson Owusu-Ansah, Emily Pasek, Abani K. Pradhan

Faculty Publications

The coronavirus disease 2019 pandemic highlighted the need for more rapid and routine application of modeling approaches such as quantitative microbial risk assessment (QMRA) for protecting public health. QMRA is a transdisciplinary science dedicated to understanding, predicting, and mitigating infectious disease risks. To better equip QMRA researchers to inform policy and public health management, an Advances in Research for QMRA workshop was held to synthesize a path forward for QMRA research. We summarize insights from 41 QMRA researchers and experts to clarify the role of QMRA in risk analysis by (1) identifying key research needs, (2) highlighting emerging applications of …

Computational Modeling Of Tool-Rock Frictional Contact With Anisotropic Damage, Yaneng Zhou, George Z. Voyiadjis

Faculty Publications

The mechanism of frictional contact is investigated between a blunt tool and quasi-brittle rocks with anisotropic damage. A recently developed anisotropic elasto-plastic-damage model is further validated using experimental results under monotonic and cyclic loadings for rocks and concrete. A finite element model of tool-rock frictional contact is validated by analytical results in the two asymptotic regimes of an elastoplastic rock. The mesh sensitivity is reduced using a fracture energy-based method for anisotropic damage. The tool-rock frictional contact is predominantly controlled by three dimensionless parameters: η, ξ, and ζ, which characterize elastoplasticity, brittleness, and anisotropic damage, respectively. The newly introduced damage …

Development Of Multifunctional Wood Composites With Integrated Phase Change Materials For Enhanced Thermal Management, Self-Healing, And Sustainability., Emmanuel Igbokwe

LSU Master's Theses

Abstract

This study focused on incorporating self-healing, flame retardancy, and energy harvesting capabilities into the wood composite to contribute to more sustainable and energy-efficient building practices. Oriented strand board has been widely used as sheath for roofing or dry walls in residential buildings. Residential buildings account for a large portion of energy consumption. Therefore, an oriented strand board with energy harvesting capability is highly desired. Additionally, flame retardancy and damage self-healing and end-of-life recycling are also critical features for buildings.

In this study, we prepared a novel oriented strand board by constructing sandwich structures. The face sheets of the sandwich …

Learning Problems Related To Stochastic Differential Equations, Jinpu Zhou

LSU Doctoral Dissertations

Stochastic differential equations (SDEs) are essential for modeling systems influenced by both deterministic dynamics and random fluctuations, with applications in a wide variety of disciplines. This thesis develops a Bayesian framework for nonparametric learning in SDEs, addressing key challenges in inference, particularly when dealing with complex systems and incomplete data. The thesis begins by establishing a theoretical foundation in optimization over Hilbert spaces, including a generalized representer theorem to address infinite-dimensional optimization problems encountered in nonparametric inference. Building on this, we introduce a Bayesian framework with shrinkage priors to learn drift functions from high-frequency data. Bayesian approach incorporates low-cost sparse …

Precision Bottlebrush Polymers: Synthesis, Characterization, And Structure-Property Relationship, Nduka D. Ogbonna

LSU Doctoral Dissertations

Bottlebrush polymers, a type of non-linear polymer characterized by densely grafted side chains on a linear backbone, offer a versatile platform for material design due to their unique thermomechanical and rheological behavior. Addressing the grand challenge of achieving structural precision for bottlebrush polymers remains crucial because traditional disperse mixtures are plagued with batch variability, limiting our ability to control their functions, and correlate theoretical predictions with experiments. To date, narrow-dispersity bottlebrush polymers remain highly heterogeneous, as they are typically synthesized from disperse linear building blocks.

To address this longstanding challenge of structural heterogeneity in brush polymers, the primary objective of …

The Structure, Oxidation States, And Energetics Of Co Nanoparticles On Ceo2(111): An Stm And Dft Study, Md Saeedur Rahman, Nishan Paudyal, Linze Du Hill, Jing Zhou, Ye Xu

Faculty Publications

Co nanoparticles (NPs) dispersed on ceria have been widely studied as active catalytic materials for many industrially relevant reactions. The detailed nature of such particles and the factors affecting their interaction with ceria remain to be better understood. In this study, a very low coverage (∼0.02 ML) of Co is deposited on a model CeO2(111) thin-film surface and is examined using scanning tunneling microscopy (STM) and X-ray photoelectron spectroscopy (XPS). The Co NPs that nucleate on terrace sites grow with coverage in this range to a maximum size of ca. 40 Co atoms, with an average diameter and height of …

Resource Harvesting For Parallel Functions In Serverless Workflows, Peiman Fotouhi

LSU Master's Theses

In the rapidly evolving landscape of cloud computing, serverless architectures have gained attention for their scalability and cost-effectiveness. This thesis aims to introduce a novel approach to maximize resource utilization in serverless environments through the concept of harvesting idle resources within Directed Acyclic Graph (DAG)-based workloads. Our proposed solution targets resource harvesting at parallel stages by utilizing Machine Learning models to accurately harvest or accelerate serverless functions. Additionally, we present a scheduling algorithm specifically designed to address the unique requirements of DAG workloads in cloud environments.

The framework leverages dynamic resource allocation techniques to identify and exploit idle resources within …

Performance Analysis Of C++ Parallel Algorithms In Hpx, Srinivas Yadav Singanaboina

LSU Master's Theses

The exponential growth in computational power and the increasing demand for high-performance applications have driven the need for greater parallel efficiency. Over the years, the number of cores in consumer-level CPUs and high-performance computing (HPC) systems has grown significantly. In response, numerous parallel programming li- braries have been developed. Each of these libraries offers unique mechanisms to enhance parallel performance. In this paper, we investigate the performance of five such paral- lel programming backends: C++ std::execution::par, OpenMP, TBB, Taskflow, and HPX. We evaluate these libraries using two sets of benchmarks. The first set focuses on standard C++ STL algorithms, including …

Evaluating Laser Tracking For The Improvement Of Quality Control Methods Of Precast Concrete, Blake A. Barbay

LSU Master's Theses

Current quality control (QC) methods of precast concrete are outdated and present challenges of human error and lengthy inspections. Current research into modernizing QC practices revolves around the implementation of laser scanners, with less focus on the possibility of using laser trackers. The aim of this study is to evaluate the implementation of laser trackers into the QC process of precast concrete by comparing time, accuracy, and cost to the traditional method of using a tape measure. The time studies and accuracy tests were performed in the pre- and post-pour of the precast concrete process at a precast concrete plant …

Command And Control Mechanisms For Post-Exploitation, Connor Hummel

LSU Master's Theses

The client-server model forms a core part of any existing network infrastructure. This interdependence between multiple client-server information systems means more vulnerabilities are open to exploitation. Once attackers gain control of an existing server, they can explore the vulnerabilities of a server system. To provide a more effective manner of defending against this type of persistent attack, this thesis aims to provide core information for understanding how post-exploitation of client-server systems works and an example attack scenario of a compromised system's behavior.

In this thesis, we identify several mechanisms used to control the attack flow and evade detection in the …

Evaluation Of Wood Fibers Derived From Different Tree Species And Processing Methods On Crop Growth And Microbial Activity In Soilless Substrates, Amanda Mizell

LSU Master's Theses

Soilless culture use is expanding as arable land and viable fumigants have decreased in availability. This has subsequently increased the demand for soilless substrates for container crop production. The primary component in most soilless substrates is Sphagnum peat moss, which is considered unsustainable due to the extensive time it takes to produce and the release of large amounts of carbon into the atmosphere during harvesting. Research into viable peat moss amendments to reduce reliance on this relatively non-renewable material has become a necessity. The most promising amendment that has been accepted in the horticulture industry as a viable amendment is …

Effects Of Longitudinal Training Walls On Two-Dimensional Flow Structure, Sediment Transport, And Bed Aggredation Using Numerical Methods And Sediment Core Analyses In Grand River, Michigan, Sumaiya Tul Siddique

LSU Doctoral Dissertations

Longitudinal training walls (LTWs) are structures oriented parallelly with the main flow and separate the channel into two sub-channels. One channel acts as the main navigational channel and the other is considered a secondary side channel. The long-term effects of the LTWs on morphodynamics and deposition remain poorly understood. This study investigated the long-term effects of the LTWs on flow, sediment transport and long-term deposition of the Grand River using numerical approaches and sediment core analysis. The effects of LTWs on 2D flow dynamics and sediment transport were investigated by using numerical approaches. The long-term deposition under the influence of …

Exploring Pre-Service Teachers' Experiences With Emerging Technologies In Secondary Education: A Phenomenological Study, Richelle M. Decuir

LSU Doctoral Dissertations

This research was an investigation of the role of emerging technologies in preparing pre-service teachers to engage with secondary learners effectively. A phenomenological approach was utilized to explore how instructional design models and constructivist learning theories shape technology training in two Southeastern public universities. The research was focused on pre-service teachers' experiences developing digital competencies, integrating instructional design, and utilizing emerging technologies in educational settings. Data was collected through semi-structured interviews and demographic surveys to understand the participants’ perspectives comprehensively. The study findings revealed that while pre-service teachers recognize the value of technology in enhancing student engagement and supporting personalized …

An In-Situ Method For Quantifying Entropy Generation In Fatigue Via A Novel Thermographic Approach, Peyton J. Wilson

LSU Master's Theses

This work features a new approach that is used to measure the rate of plastic work during a cyclic fatigue test, based on the first and second laws of thermodynamics. Using the one-dimensional Fourier heat equation coupled with the concept of fracture fatigue entropy, the rate of plastic work during fatigue can be measured without the need to interrupt a fatigue test, and the accumulated entropy to failure can be quantified. Experimental fatigue tests are conducted on Aluminum 6061-T6 specimens under cyclic axial loading and Carbon Steel 1018 specimens under fully reversed cyclic bending loading. The obtained results in addition …