Mechanical Engineering Commons^™

A Maximum Energy Release Rate Computational Framework For Fatigue Crack Trajectory And Life Prediction Under Mixed-Mode Proportional And Nonproportional Loading, Nahla Helmy Matar

Theses and Dissertations

The problem of mixed-mode fatigue crack growth has been a persistent research challenge. The determination of fatigue crack propagation direction directly impacts the safety and integrity of components and structures, making it crucial in various industrial applications, including welded drilling pipes, aerospace, and automotive engineering. Unlike uniaxial loading, mixed-mode cracks tend to change direction frequently (kinking), and nonproportional loading adds to the complexity of the problem. This research aims to estimate the crack propagation direction and fatigue crack life in linear elastic materials subjected to mixed-mode (I+II) loading conditions under proportional or non-proportional cyclic loading. Numerical software was developed based …

Cavitation In Pumps And Propellers: Causes, Effects, Prevention, And Future Trends, Gillian Negron Burgos, Olivia Wilson

Discovery Day - Daytona Beach

In this research, we will explore cavitation in pumps and propellers, including its causes, effects on system performance, prevention methods, and future engineering solutions. Cavitation occurs when the local pressure of a flowing liquid drops below its vapor pressure, forming vapor-filled bubbles that collapse and damage mechanical components. Disciplines such as fluid mechanics, thermodynamics, and materials science contribute to understanding and mitigating cavitation in fluid machinery.   When vapor bubbles collapse near metal surfaces, they generate localized shock waves that cause pitting, erosion, vibration, and noise. These effects reduce efficiency, increase maintenance requirements, and shorten the lifespan of rotating machinery used …

Magnetic Field-Induced Transformation In Polycrystalline Ni2mnal Heusler Type Magnetic Shape Memory Alloy, Choji J. Daches, Joseph W. Newkirk, Mario Buchely, Laura N. Bartlett

Materials Science and Engineering Faculty Research & Creative Works

The martensitic and magnetic transformations, as well as the mechanical properties, of Ni₂MnAl alloys in as-cast (AC) and heat-treated (HT) conditions were investigated. Magnetic-field-induced strain was evaluated via magnetostriction, with reversible strains of 0.14% and 0.2% achieved in the martensitic phase at 2 K for the AC and HT alloys, respectively. Transformation temperatures and Curie temperatures were determined under constant applied magnetic field, revealing that γ-phase inclusions in the AC microstructure suppress antiferromagnetic domain response, yielding a lower magnetization (∼8.4 emu g⁻¹) compared to the HT alloy (∼13.4 emu g⁻¹). Both alloys exhibited hysteretic behavior in the martensitic state and …

Direct Ink Writing Of Functional Fiber/Granular Composites, Zhuoyuan Yang

Doctoral Dissertations and Master's Theses

Direct ink writing provides a versatile manufacturing route for fabricating functional fiber and granular composites with controlled architecture, tunable interfaces, and customized material distributions. Fiber reinforced composites offer high stiffness, strength, fatigue resistance, and functional anisotropy, while granular composites provide scalable access to particle based structures with high material efficiency and broad resource compatibility. However, the additive manufacturing of these composite systems remains challenging. For fiber based composites, precise control of fiber placement, matrix impregnation, interfacial bonding, and freestanding deposition is difficult to achieve during printing. For granular composites, stable particle flow, controllable packing, binder infiltration, and shape retention are …

Electropulse Annealing: Phase Composition Of Tial6v4, Vaughn Eckhardt, Ethan Croke, Ian Baker, Russ Taylor

Wetterhahn Science Symposium Posters

Titanium alloy TiAl6V4 is the most ubiquitous titanium alloy used for dental care, aerospace manufacturing, and for high performance vehicles. The material typically undergoes a thermal heat  treatment, but electropulse annealing is another process that involves sending current through the material to heat it up at a quicker rate. The rate of post-annealing cooling is high, and around the material's critical point, its two components, alpha and beta phase, change in relative concentration. After testing multiple current densities and temperatures, in general, as the current density that the sample received during electropulse annealing decreased, both the alpha and beta phases …

An Analytical Framework For Quantifying Urban And Community Resilience To Natural Hazards From Cell-Phone Gps-Location And Traffic-Flow Data, Georgios Chatzikyriakidis

Civil and Environmental Engineering Theses and Dissertations

Urban areas are increasingly exposed to natural hazards while accommodating a growing share of the global population, yet a consistent science-based framework for quantifying urban and community resilience remains lacking. This dissertation develops a physics-based analytical framework grounded in statistical mechanics and the quantitative theory of Brownian motion. A city is conceptualized as a complex medium in which citizens move analogously to Brownian particles within a viscoelastic environment, influenced by socioeconomic interactions and infrastructure functionality.

A central premise is that urban resilience, interpreted as engineering resilience (an outcome), can be quantified through a single metric: the mean-square displacement MSD=⟨r²(t)⟩, of …

Plastic Material Analysis And Bonding In Small Aquatic Vessels, Andrew R. Orr

Honors College Theses

This project presents the design and development of a suitable vessel for small-scale aquatic applications. The developed project is used for a remote-controlled duck hunting system, and the parameters of the design are based on the requirements for the system as a whole. Traditionally, plastics are fabricated using blow molding to create a single seamless form. However, for small-scale prototyping with limited resources, this method of fabrication is unsustainable for short-term, non-industrial design applications. As a result, an existing longer hull is selected and shortened to meet the required project length. The project evaluates multiple initial hull designs, ultimately selecting …

Ballistics Characterization Of Micro-Truss Reinforced Lunar-Inspired Geopolymer Concrete For Space Construction, Phoebe G. Johnson

Honors Theses

This research investigates the ballistics response and compressive strength of a Fly Ash/ Lunar Regolith hybrid geopolymer concrete developed for space construction. The study aimed firstly to optimize the Fly Ash/ Regolith mix ratio for maximum mechanical performance and secondly, to evaluate the effectiveness of carbon-fiber micro-truss reinforcement, produced by 3D printing, in mitigating damage from high-velocity impacts. Concrete specimens with varying Fly Ash-to-Regolith ratios (100-50% Fly Ash) were fabricated and tested under compression and ballistic loading. Compressive strength tests followed ASTM C109 using a 110 Kip 810-MTS testing apparatus on both unreinforced and reinforced 2” cubes. For unreinforced samples, …

Brine Solidification And Metals Sequestration Using Lignocellulosics, Frank Kvietok

World of Coal Ash Proceedings

Coal ash has historically been used as a convenient, on-site solidification material for brines generated from flue gas desulfurization at power plants. As alternate utilization scenarios are developed for coal ash, lignocellulosic (wood-based) sorbents can serve as a highly efficient substitute for the solidification process. Results will be shared for a variety of different brine types: thermally reduced, thermally reduced and neutralized, and reverse osmosis. In addition to solidification performance, which demonstrated a 3-4x mass of liquid vs mass of sorbent factor, studies were conducted to quantify the strength of binding to the wood-based sorbent for a broad range of …

Practical Guidelines For Pump Testing Of Ccr: Workflow, Design, And Lessons Learned., Nathanial Keller, Brian Hennings, Vic Modeer, Katie Moran

World of Coal Ash Proceedings

This session presents a streamlined approach for pump testing of coal combustion residuals (CCR) to maximize hydraulic information with limited well installations, variable pumping rates, and short tests. Pre-test forward modeling identifies well offsets (typically 5–10 ft) and test durations (~2–6 hours) to yield measurable and analyzable drawdown at observation wells despite low pumping rates. Field execution consists of short step-drawdown testing to evaluate well specific capacity and select pumping rates for a constant rate test with one or more observation wells. Test results facilitate analysis of transmissivity and storativity of the CCR. Applied at two Midwestern sites with different …

Simplified Approximate Procedure For Assessing The Implications Of Updated Usgs Seismic Hazard Models On Seismic Stability Assessments Of Ccr Impoundment Facilities, Nick Mcclung, Matt Bishop, Adrian Pena-Iguaran, Seda Gokyer-Erbis

World of Coal Ash Proceedings

Selection of appropriate seismic design ground motions remains a key challenge for seismic stability assessments of coal combustion residual (CCR) impoundment facilities, particularly where regulatory guidance does not specify a required hazard model. This paper examines the implications of using Uniform Hazard Spectra (UHS) derived from the 2014 versus the 2018 U.S. Geological Survey (USGS) National Seismic Hazard Model (NSHM) for seismic amplification and stability evaluations of the Tennessee Valley Authority (TVA) Widows Creek Fossil (WCF) Plant CCR Management Units. The 2018 NSHM incorporates updated understanding of seismicity in the central and eastern United States and generally predicts higher ground …

Before The Limit Hits: Lessons From A Proactive Construction Air Monitoring Program, Brian Egan, Nicholas Golden, Wendy Depp

World of Coal Ash Proceedings

This presentation describes a comprehensive air monitoring program designed to protect workers and nearby neighborhoods during ash pond closure work. The program uses three main components: project (or boundary) monitoring at the site perimeter to track dust near the project boundaries, work area monitoring placed near active construction zones, and personal sampling on individual workers at regular intervals. Together, these approaches provide data on both community impacts and worker exposures, helping the team respond quickly when levels approach action limits. The Teams actions prior to exceedance of regulatory limits has helped prevent exposures. The talk will explain how monitors are …

Integrating Advanced Geochemical Workflows With Modern Statistical Tools To Improve The Decision-Making Process At Ccr Sites, A Case Study, Glenna Thomas

World of Coal Ash Proceedings

While statistical assessment provides the foundation for CCR compliance reporting, incorporating a holistic geochemical framework transforms statistics from a compliance requirement into a powerful predictive tool. Strategic geochemical insight established the basis of understanding needed to support successful statistical approaches and to ensure that statistical outcomes reflect actual groundwater behavior. Whether it is trend analysis, delineating source mechanism, or updating geochemical conceptual site models (GCMs), geochemical context provides the technical foundations for statistical outputs and methods. A continuously refined GCSM enhances the ability to anticipate how groundwater chemistry should evolve, improving interpretation and predictive capability. This allows practitioners to understand …

Establishing Groundwater Monitoring Systems Under The Legacy Rule: A Systematic Approach For Utilities, Chris Hoglund

World of Coal Ash Proceedings

The USEPA’s Legacy CCR Rule introduces new requirements for establishing groundwater monitoring systems at Legacy Surface Impoundments (LSIs) and Coal Combustion Residual Management Units (CCRMUs). These requirements present unique challenges for electric utilities, particularly at inactive or historically operated facilities where subsurface data are limited and CCR units may have nontraditional configurations such as linear roadways, elongated embankments, or distributed disposal areas. Utilities must also determine how best to apply single-unit or multi-unit monitoring approaches, integrate newly regulated units into existing monitoring networks, and align monitoring system design with planned closure strategies. This presentation outlines a systematic, defensible framework to …

Risk Evaluation Of Linear Coal Combustion Residual Management Unit (Ccrmu) Fills, Qian Zhang, Andrew Bittner, John Kondziolka, Masoud Arshadi

World of Coal Ash Proceedings

In 2024, the US Environmental Protection Agency (US EPA) established new regulations for coal combustion residual management units (CCRMUs), defined as coal combustion residual (CCR) deposits placed on power plant properties outside of landfills or surface impoundments. US EPA supported the rulemaking with modeling-based risk analyses and established regulatory requirements based on fill size. Linear CCRMU, such as backfill along pipelines or haul roads, have individual segments that may be composed of a small amount of mass below the threshold for regulation, but the cumulative mass over the full linear feature extent may exceed regulatory thresholds. This study applies US …

Application Of Mine Tailings Flow Failure Assessment On Ccr, Zachary Fallert

World of Coal Ash Proceedings

A new geotechnical stability analysis method has been implemented for a CCR surface impoundment to aid in design for temporary cut slopes and final closure grades. Conditions have come to light after significant tailings dam failures occurred across the globe, specifically those exhibiting flow failures (i.e. failures in which tailings behave a liquid and flow out of the facility). These failures have come under intense scrutiny as the failures pose significant risk to public safety and the environment and have been observed in CCR. Additionally, static liquefaction has arisen as another potential but less well understood causative mechanism. As the …

Lessons Learned: Commissioning An Fgd Wastewater Treatment System, Bella Triolet, Mckale Grant, Louis Manigault

World of Coal Ash Proceedings

Stantec recently supported commissioning a flue gas desulfurization (FGD) Wastewater Treatment System in accordance with the 2020 Environmental Protection Agency (EPA) Effluent Limitations Guidelines (ELG) Rule, which requires that coal fired power plants meet their more stringent requirements by December 31, 2025. With the addition of the 2024 EPA ELG Rule, coal fired power plants will now be expected to move to zero liquid discharge (ZLD) systems or permanently cease coal combustion by 2034. Due to this change, it is likely that coal fired power plants will be looking to design and install ZLD systems within the next decade. While …

Risk Evaluation Of Linear Coal Combustion Residual Management Unit (Ccrmu) Fills, Qian Zhang, Andrew Bittner, John Kondziolka, Masoud Arshadi

World of Coal Ash Proceedings

In 2024, the US Environmental Protection Agency (US EPA) established new regulations for coal combustion residual management units (CCRMUs), defined as coal combustion residual (CCR) deposits placed on power plant properties outside of landfills or surface impoundments. US EPA supported the rulemaking with modeling-based risk analyses and established regulatory requirements based on fill size. Linear CCRMU, such as backfill along pipelines or haul roads, have individual segments that may be composed of a small amount of mass below the threshold for regulation, but the cumulative mass over the full linear feature extent may exceed regulatory thresholds. This study applies US …

Site Characterization, Design, Permitting, And Construction For Clean Closure Of A Small But Challenging Legacy Ccr Disposal Impoundment, John Garten, Bob Baker, Lee Lenhart

World of Coal Ash Proceedings

The Lay of Land Area (LOLA) is a 10-acre (40,468 square meters) legacy disposal impoundment containing approximately 55,000 cubic yards (42,000 cubic meters) of sluiced coal combustion residuals (CCRs) produced during startup operations of a former fossil plant. Most of its perimeter is bounded by water, with a river to the north and a cooling water lake to the south. The entire area lies within a 100-year floodplain, is heavily forested, and groundwater is typically encountered within a few feet of the existing ground surface. As part of an overall CCR closure-by-removal and ash beneficiation program, planning, design, permitting, and …

Trimble County Pond Closures, Steven Turner, Shanti Montgomery

World of Coal Ash Proceedings

The Trimble County Closure Project is a 5-year project to close the 40-acre (161,900 square meters) Gypsum Storage Pond (GSP) through closure-by-removal and the 100-acre (404,700 square meters) Bottom Ash Pond (BAP) through closure-in-place in accordance with coal combustion residual (CCR) Rule. The excavated gypsum from the GSP was “Beneficially Reused” to fill the BAP to the prescribed grade for drainage through a monitored outfall to the adjacent creek. The daily plant produced CCRs of fly ash, bottom ash, and gypsum were also used for four years to supplement the filling of the BAP as well as several onsite soil/rock …

Dewatering System Operations And Modeling Of A Bottom Ash Ccr Surface Impoundment, Craig Schuettpelz, Todd Stong, Ben Sieren

World of Coal Ash Proceedings

Dewatering of coal combustion residual (CCR) surface impoundments is a technically challenging item for sites with CCR units at closure. Generation has ceased at this site where fly ash was mostly sold for beneficial use and bottom ash was sluiced to composite-lined CCR surface impoundments to passively drain prior to landfilling. During site closure and restoration, bottom ash and relatively minor amounts of other permitted waste materials were consolidated into the site’s landfill and bottom ash impoundment. The bottom ash impoundment entered closure 5 years ago with installation of a final cover system and construction of a sump to allow …

Building Better Partnerships: Design-Build Lessons From The Ash Pond Closure Front Lines, Brian Egan, Nicholas Golden, Mark Edlebeck

World of Coal Ash Proceedings

This presentation shares lessons learned on an ash pond dig-and-haul project delivered by a design-build team with CTI providing engineering and Fisher Contracting delivering construction services. CTI and Fisher Contracting will discuss how they formed their partnership, what makes a good teaming arrangement work, and the challenges that come with working closely together. This team has worked side by side from early design through construction, which has helped cut costs and keep the project on schedule. The talk will show how the partners divide tasks, then adjust roles as needed instead of locking into a fixed plan. In some cases, …

Illinois Coal Ash Impoundment Assessment, Randy Locke

World of Coal Ash Proceedings

Coal combustion residuals (CCR) present one of the most significant waste management challenges in the United States. Illinois hosts 72 coal ash impoundments at 23 facilities across 22 counties. In 2019, the state enacted Public Act 101 0171 (Coal Ash Pollution Prevention Act), followed by Illinois Administrative Code Title 35, Part 845, establishing CCR surface impoundment standards. Even with federal and state requirements, significant gaps remain in identifying management options and site-specific risks. Key limitations include: (1) incomplete understanding of ash composition and variability within and among impoundments; and (2) fragmented information on impoundment physical properties, operational status, and geological …

A Novel Geospatial Tool For Assessing Risks And Opportunities For Conversion Of Ccr Closures Into Productive Solar Energy Generation Sites, Marc Theisen

World of Coal Ash Proceedings

Closure of Coal Combustion Residuals (CCR) surface impoundments and landfills offers unique opportunities for conversion to solar power sites with the potential to offset costs of post-closure care via generation of clean electricity. In 2023 the US Environmental Protection Agency (EPA) collaborated with the National Renewable Energy Laboratory (NREL) to create a report entitled “Coal Ash Disposal Sites and Opportunities for Solar Photovoltaic Development” (EPA Publication #540-S-23-004). The purpose of this document was to identify closed CCR units and provide key factors for their potential for solar photovoltaic (PV) development. In 2022, the EPA’s RE-Powering Initiative identified 772 current CCR …

Establishing A Roadmap For The Planning, Design, And Construction Of A Water Treatment System For A Ccr Unit Closure, Mariah Schroeder, Matthew Balance

World of Coal Ash Proceedings

The treatment of water from a CCR unit is an important step in the closure strategy for surface impoundments to comply with 40 CFR §257.102(d)(2)(i) of the CCR rule. The unwatering and dewatering of a surface impoundment is a necessary first step in ensuring that the eventual closure of the unit will meet the requirements for closure in place described in 40 CFR §257.102(d). Depending on the operational conditions and requirements of the plant, the NDPES discharge limits, and the impacted water quality, the water treatment system needs can vary greatly. This presentation will outline a roadmap for assessment, evaluation, …

The Modern Hydraulic Containment System: Using Automation, Telemetry And Data Dashboarding To Meet Client And Regulatory Objectives At A Coal Combustion Residual (Ccr) Site, Brian Hennings, Christopher Glidden, Vic Modeer, J. Austin Bond

World of Coal Ash Proceedings

The site, a former coal-fired power plant in southern Illinois, generated coal combustion residuals (CCR) such as bottom ash and fly ash stored in surface impoundments. Adjacent to the Ash Pond, boron was detected in groundwater above the state standard of 2 mg/L. In late 2025, a groundwater extraction system was installed to control hydraulic conditions and prevent boron migration offsite until source control measures are completed. The system is expected to operate for up to 11 years. Three-dimensional groundwater modelling was used to support system design, helping to identify optimal well locations and flow rates for effective containment. Components, …

Strategic Workforce Solutions In The Coal Ash Industry, Stuart Keeter

World of Coal Ash Proceedings

The coal ash industry stands at a pivotal moment, shaped by legacy environmental events, evolving engineering standards, and a rapidly shifting workforce landscape. This session explores the strategic talent challenges facing consultants, civil engineering firms, and utilities in 2026 and beyond. Drawing from data sources including MRI, LaborIQ, AGC, and the U.S. Bureau of Labor Statistics, the presentation highlights: • The impact of historic coal ash incidents (TVA Kingston, Duke Dan River) on industry best practices. • The convergence of civil, environmental, and power sectors in driving remediation and innovation. • Alarming workforce trends, including the retirement of 12,000 professionals …

Establishing Sustainable Vegetation On A Challenging Legacy Ccr Site, Derek Oosterhouse, Blake Arthur

World of Coal Ash Proceedings

American Electric Power (AEP) is closing and restoring a legacy Coal Combustion Residuals (CCR) site in Ohio that once held a power plant that pioneered innovative steam generation technology. The plant was closed in 1975. Today, the legacy CCR site is being transformed back to natural, sustainable vegetation. To comply with and close the Stormwater Pollution Prevention Plan (SWPPP) permit, permanent stabilization is required on the site. AEP, one of the largest electric companies in the country, holds a core principle to respect the environment through creative sustainable solutions. AEP connected with Profile Products, the world’s largest manufacturer and supplier …

Closure Of A Process Water Impoundment, Todd Stong, Shane Stockdill, Erin Hunter

World of Coal Ash Proceedings

Rainbow Energy Center’s (REC’s) Coal Creek Station manages process water in various engineered impoundments across the facility. As part of the ongoing life of the plant, one of the site process water ponds has been decommissioned to allow for construction of a new coal combustion residuals (CCR) impoundment within the same footprint. In order to transition from a non-CCR impoundment to construction of a CCR impoundment, the existing impoundment was closed and decommissioned in 2025. The composite-lined process water impoundment intended for closure previously operated from the early 1990s. To effectively close the impoundment, a closure verification plan was developed …

Future Strategies For Beneficial Use Harvesting, Gabe Lang, Patrick Kiser

World of Coal Ash Proceedings

TVA is the largest public power company in the U.S. and has historically operated a fleet of 12 coal-fired plants as part of their diverse generating portfolio. To date, eight of the coal plants have been retired and the remaining four plants are projected to shut down in the next couple of decades. The decommissioning of these plants is driving a transition to harvesting of ponded and landfilled CCR’s to continue to support ready-mix concrete and other industries that enable infrastructure development. However, the regional market demand limits the ability to initiate widespread harvesting activities during near-term CCR Unit closure …