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Ice-templated ceramic-metal composites modified by interfacial metal aluminates
(Montana State University - Bozeman, College of Engineering, 2024) Marotta, Amanda Rose; Chairperson, Graduate Committee: Stephen W. Sofie; This is a manuscript style paper that includes co-authored chapters.
Interpenetrating phase (3-3) composites consists of two phases which are fully percolating throughout one system. Research efforts have been made towards routes to fabricate these composites that will allow for them to be utilized for applications like heat spreaders and leading-edge parts. Freeze-tape casting offers a potential avenue for developing 3-3 composites. The system can exhibit complete, long-range alignment through freeze-tape casting, in which both phases of the composite will be in constant periodicity of one another. To explore the potential of such ordering in 3-3 composites, ceramics, such as, yttria- stabilized zirconia (YSZ), alumina (Al 2 O 3) and zirconium diboride (ZrB 2) were freeze-tape casted and sintered to allow for second phase incorporation. Second phases, like copper (Cu) and silicon carbide (SiC) were utilized, so that ceramic-metal (cermet) freeze-tape casted composites and ultra-high temperature ceramic (UHTC) freeze-tape casted composites could be characterized. Initial composite property predictions were made using rule of mixtures (ROM). The work contained in this dissertation demonstrates that freeze-tape casted 3-3 composites can exhibit novel 3-axial anisotropic thermal behavior, and that, by ordering the percolating phases, high-temperature thermal behavior may be enhanced. This work, also, demonstrated that ceramic-metal interfaces are fragile, exhibiting thermal stress at the interface upon thermal cycling. Fostering interfacial adhesion between metal and ceramic phases is a primary tool for manipulating cermet properties. Common approaches to ceramic-metal joining include metallization and active brazing techniques. Though improvements in mechanical properties are notable, the functional capabilities can be sacrificed. To overcome these limitations, a novel approach, via a metal aluminate (copper aluminate), has been utilized to alleviate thermal stress along a ceramic-metal interface, and maintain adhesion of the ceramic-metal up to 100 psi. Mechanistically, it was not well- understood, as to what role copper aluminate played in modifying ceramic-metal interfaces. Chapter 5 of this work elucidates copper aluminate's role in fostering a ceramic-metal interface. By analyzing the surface and cross-sectional features of the cermet, it is discovered that through the formation of copper aluminate, porosity/roughness occurs to the bulk ceramic, allowing avenues for the metallic phase to penetrate through the thickness, fostering a mechanical interlocked joint.
Applying advanced materials characterization techniques for an enhanced understanding of firn and snow properties
(Montana State University - Bozeman, College of Engineering, 2024) Schehrer, Evan Nicholas; Chairperson, Graduate Committee: Kevin Hammonds; This is a manuscript style paper that includes co-authored chapters.
Understanding snow microstructure and stratigraphy is critical for enhancing modeling efforts and instrument validation for the polar regions and seasonal snow. Controlled laboratory experiments help with these efforts and are essential for enhanced comprehension of polar firn densification, snow metamorphism, avalanche mechanics, snow hydrology, and radiative transfer properties. This dissertation aims to characterize snow and ice as they relate to the mechanical and sintering properties of simulated firn subject to trace amounts of sulfuric acid (H 2SO 4). Studies were also developed to characterize faceted snow crystallographic orientation using electron backscatter diffraction (EBSD) and understand the observed reflectance of remote sensing instruments related to mapping changing snow microstructure. To investigate the effects of soluble impurities, 50 ppm H 2SO 4 and impurity-free ice grains were developed to simulate polar firn and then subjected to a series of unconfined uniaxial compression to monitor the effect in mechanical strength at different temperatures and strain rates. Meanwhile, the role of sintering is less defined for ice grains that contain impurities. Two experiments were developed to quantify sintering rates with H 2SO 4. One experiment tracked the changes in microstructure at isothermal conditions using X-ray computed microtomography over 264 days. A second experiment used angle of repose tests to characterize the subsecond sintering between H 2SO 4 and impurity-free ice grains. In addition, it is well known that snow has constantly changing microstructure once deposited during precipitation events. These changes have an immediate impact on the crystallographic and optical properties. Faceted snow crystals, collected from the field and artificially grown, were analyzed using EBSD to map vapor-deposited growth along the three ice (Ih) crystallographic planes. Moreover, validation of remote sensing techniques such as near-infrared hyperspectral imaging (NIR-HSI) and lidar is essential for accurate field measurements. In the laboratory, an intercomparison test was conducted for NIR-HSI and lidar to analyze bidirectional reflectance returns, mapping the effective grain size of snow under different microstructural conditions and during melt/freeze events and surface hoar growth.
Characterization of multi-physics aging effects on the thermomechanical viscoelastic response of ultra high molecular weight polyethylene fiber reinforced composites
(Montana State University - Bozeman, College of Engineering, 2024) Weaver, Jonmichael Andrew; Chairperson, Graduate Committee: David A. Miller
Ultra High Molecular Weight Polyethylene (UHMWPE) fiber reinforced composites have a high strength-to-weight ratio and are gaining attention as a material of choice for specialized applications subjected to extreme environmental conditions. Users value the water-repellent, lightweight, and flexible nature of the material for applications where weight is crucial. Marine, aerospace, and alternative energy sectors are exploring UHMWPE fiber reinforced composites for specialized applications in demanding environments where strength, flexibility, and weight efficiency are important design criteria. The viscoelastic and hydrophobic nature of UHMWPE makes it an attractive replacement for Kevlar® in ballistics protection shields and other industrial applications, providing similar performance while achieving upwards of 40% reduction in weight. However, the durability of UHMWPE composites under real-world aging conditions remains insufficiently examined. This research investigates how the viscoelastic properties of UHMWPE fiber reinforced composites, created through various manufacturing techniques, are altered after exposure to harsh conditions including immersion in water, temperature variations, humidity, and UV exposure. Additionally, the composites were irradiated with: X-rays, gamma-rays, and neutrons. After exposure to adverse environments, the thermomechanical viscoelastic response was characterized through Dynamic Mechanical Analysis (DMA). Surface morphology was evaluated using a field emission scanning electron microscope. DMA revealed an increase in the storage modulus with aging; however, elevated temperature creep tests showed that UV and hygrothermal aging had a higher creep compliance and decreased the ability of the composite to recover strain after unloading. Both single layer and pressed UHMWPE panels showed an increase in weight after submersion in water. Distilled water resulted in a faster rate of hydrolysis in the matrix than did salt water. The UV, gamma-ray, and neutron environments caused the composites to become brittle and yellow through chain scission and crosslinking, whereas the X-ray radiation exposure did not cause a measurable effect. Analysis on the surface of these composites after aging suggested the matrix protects these fibers from damage in harsh environments. Synthetic rubber matrix materials aged at a faster rate than the polyurethane rubber matrix materials. Increasing the strain rate showed an increase in moduli response during tensile DMA. These results quantify the limitations and strengths of this material for future models to accurately predict the lifespan and expand the application of this performance material in extreme environments to ensure safety for applications ranging from extreme sports to aerospace.
Does bone-to-cartilage fluid transport exist and is it relevant to joint health?
(Montana State University - Bozeman, College of Engineering, 2024) Hislop, Brady David; Chairperson, Graduate Committee: Ronald K. June II; This is a manuscript style paper that includes co-authored chapters.
Osteoarthritis (OA) afflicts millions of people each year. The onset of OA has been associated with many factors including increased bone-cartilage fluid transport, yet a cure remains elusive. To implicate bone-cartilage fluid transport in the progression of OA, further studies are needed on fluid transport in health. Recent studies have challenged the assumption that no fluid transport occurs between bone and cartilage in healthy joints. However, many gaps remain in our understanding of bone-to-cartilage fluid transport, including 1) do fluid pressure gradients develop at the bone-cartilage interface, 2) do traumatic injuries impact subchondral bone stiffness, and synovial fluid metabolism 3) do larger molecules move from bone-to-cartilage and does cyclic loading enhance such movement, 4) what material properties influence bone-to-cartilage fluid transport 5) do distinct metabolism changes occur with osteoarthritis, evaluated using a novel clustering method. Our results showed the development of fluid pressure gradients at the osteochondral interface, and that cyclic compression enhances bone-cartilage fluid transport. Furthermore, our results showed that proteoglycan loss, and decreased subchondral bone stiffness increased bone-cartilage fluid transport. Finally, we showed that in the first week after traumatic joint injuries (e.g., ACL tears) subchondral bone volume decreases, and subchondral bone stiffness increases, while the synovial fluid metabolism shifts. In conclusion, we showed that osteochondral fluid transport is enhanced by cyclic compression for larger molecules than previously studied (3kDa dextran), and that material parameters changes associated with the progression of OA alter bone-cartilage fluid transport. These studies provide novel understanding of bone-to-cartilage fluid transport, leading us one step closer to understanding OA as a whole joint disease.
An experimental study of drying in porous media in novel 2D micromodels with dual porosity
(Montana State University - Bozeman, College of Engineering, 2024) Habib, Md Ahsan; Chairperson, Graduate Committee: Yaofa Li
Drying of porous media is pervasive in numerous natural and engineering processes, such as oil recovery, CO 2 storage, and critical zone science. Drying is essentially a multiphase flow process, where the liquid phase evaporates and is displaced/replaced by the gaseous phases, as vapor diffuses out of the porous structure. In terms of pore structure and other physical characteristics like porosity and permeability, many porous matrices exhibit multi-scale heterogeneity. For instance, in critical zone, soil is often viewed as a hierarchical organization: primary particles form aggregates, which in turn form macroaggregates, effectively leading to a dual-porosity medium. Numerous activities, including gases and water transport, are known to be controlled by the resultant multiscale flow dynamics and inter-/intra-aggregate interaction during drying. However, the fundamental physics underlying drying of porous media with dual porosity is not well understood from a fluid mechanics perspective. In this work, a novel 2D microfluidic device fabrication technique has been developed. To study the multi-phase flow of air and water, emphasizing the multi-scale interaction, pore structure, and role of film flows, three distinct types of microfluidic devices have been fabricated, which bear the innovative three-layer glass-silicon- glass architecture, providing precise structural control and excellent optical access from both top and bottom. An innovative dual-magnification imaging technique has been introduced adapted for micro-PIV and epi-fluorescent microscopy which offers insightful information about the flow dynamics at both the micro- and macro-scales concurrently. In this thesis, two distinct types of experiments are outlined, focusing on diffusion-driven drying and flow-through drying, utilizing three diverse micromodels characterized by varying porous structures and distributions. The experimental results have presented the overall drying dynamics observed in different micromodels, each featuring unique porous configurations. The impact of porous geometry and external flow conditions on drying rate and associated pore-scale physics is thoroughly examined. The findings encompass a comprehensive overview of micro-macro pore interactions, as evidenced by separated saturation distribution, displacement rates, and other pertinent flow parameters. The findings have reflected the influence of pore geometry, distribution, hydraulic connectivity, and film flow on the observed effects.
Risk mitigation focused on surgical care using process improvement methodologies in rural health systems
(Montana State University - Bozeman, College of Engineering, 2023) Sitar, Nejc; Chairperson, Graduate Committee: Bernadette J. McCrory; This is a manuscript style paper that includes co-authored chapters.
Rural healthcare is represented by approximately one-third of community hospitals in the United States primarily in the Midwest and Western United States. Due to the lack of resources and the demographic characteristics of rural populations, rural community hospitals are under constant pressure to meet Center for Medicare & Medicaid Services (CMS) quality requirements. Meeting CMS quality requirements is particularly challenging in surgical care, due to the lower volumes and research opportunities, in addition to a shortage of qualified surgical specialists. The perioperative surgical home (PSH) model was established as a health management concept in a rural community hospital located in the Northwest of the United States to improve the quality of care by providing a longitudinal approach to patient treatment. The main opportunities for PSH improvement were identified in the "decision for surgery," "preoperative," and "postoperative" stages of the PSH model. To improve PSH clinic performance this thesis proposes an improved National Surgical Quality Improvement Program (NSQIP) calculator User Interface (UI), as well as a new prediction model for predicting total joint arthroplasty (TJA) Length of Stay (LOS). The improved layout of the NSQIP calculator was developed based on two approved surveys by card sorting and Borda count methodology, while the new prediction model for predicting TJA patients' LOS was based on the Decision Tree (DT) machine learning model. A usability study of the NSQIP calculator UI identified opportunities for future improvements, such as the reorganized layout of postoperative complications and the addition of a supporting tool that would clearly define postoperative complications. The new DT prediction model outperformed a currently used NSQIP calculator in the prediction accuracy of TJA LOS, as it resulted in lower Root-mean-Square-Error values. Furthermore, the structure of the DT model allowed better interpretability of the decision-making process compared to the NSQIP calculator, which increased the trust and reliability of the calculated prediction. Despite some limitations such as a small sample size, this study provided valuable information for future improvements in rural healthcare, that would enable Rural Community Hospitals to better predict future outcomes and meet the strict CMS quality standard.
The effects of angled insoles on short radius flat-track running mechanics
(Montana State University - Bozeman, College of Engineering, 2023) Bianchini, Christopher David; Chairperson, Graduate Committee: Corey Pew
While indoor track allows athletes to compete during the winter period of December to February, injury rates during the indoor track and field season are 16% higher than the outdoor season. Increases in injury rates are often attributed to the shorter turn radii experienced by athletes when competing on a 200m indoor track as opposed to the longer turn radii of a 400m outdoor track. A common method of counteracting these asymmetries is to bank the turns of a 200m indoor track. Aligning the athlete's resultant force vector perpendicular to the running surface can alleviate many of the running form abnormalities caused by turn running. However, the high cost of implementing a banked indoor track can be prohibitive to many programs who currently have a flat track facility. To this end, we have developed two experimental insoles designed to alleviate the asymmetries experienced during turn running: a physically angled foam insole and an insole containing an angled stiff mid-plate. Insole function was tested through human participant running trials to identify their effects on indoor flat track running mechanics. 12 NCAA Division 1 track and field athletes (6 male, 6 female, age: 21 + or - 2 years, mass: 61.4 + or - 11.4 kg, height: 1.77 + or - 0.17 m) who specialize in distance and mid-distance running provided informed consent to participate in this Institutional Review Board-approved protocol. Kinematics, muscle activation, and ground interaction variables were monitored during running trials and used to compare the effects of the insoles on running biomechanics. The physically angled insole produced positive results for ankle joint angles and ground interaction variables for turn running. The angled plate insole positively affected right-side ankle joint angle positioning and did not significantly impact straight running mechanics. Both insoles produced higher levels of muscle activation asymmetry, indicating that this may be a required effect of turn running regardless of joint angle positioning and ground interaction. While the angled plate insoles showed almost no impact on straight or turn running mechanics, the wedge insoles functioned effectively to alleviate several asymmetries related to turn running.
Bio-trapping ureolytic bacteria on sand to improve the efficiency of biocementation
(Montana State University - Bozeman, College of Engineering, 2023) Ugur, Gizem Elif; Chairperson, Graduate Committee: Chelsea M. Heveran; Adrienne J. Phillips (co-chair); This is a manuscript style paper that includes co-authored chapters.
Microbially induced calcium carbonate precipitation (MICP) has emerged as a novel biocementation technique for its potential solution to sustainable construction. Although current MICP approaches have made significant progress, achieving spatial control over biomineralization is challenging due to its complexity, which is affected by many factors, such as microorganisms, reaction kinetics, and environmental factors. Spatially controlling biomineralization for building or targeted repair of materials can significantly improve efficiency and sustainability while achieving desired outcomes. The purpose of this thesis was to assess whether biomineralization can be enhanced through surface pre-treatment of sand using amino silanes, such as 3-aminopropyl-methyl-diethoxysilane (APMDES), which is one form of spatial control of biomineralization through prescribing the location of the microbes. Moreover, a preliminary study was conducted to assess whether biomineralized sand, with and without the APMDES treatment, can be recycled and reused for biomineralization of subsequent generations. The impact of APMDES treatment on bacterial adhesion on sand, growth, and urease activity was analyzed. Biocementation efficiency was evaluated by comparing compressive strength and calcium gain of APMDES-treated sand with untreated sand. APMDES treatment promotes abundant and immediate trapping of bacteria on sand surfaces through increased electrostatic interaction that attracts negatively charged walls of bacteria to positively charged amine groups. While APMDES treatment compromises microbial viability, it preserves the urease enzyme for catalyzing urea hydrolysis. APMDES-treated sand achieved comparable strength with fewer bacterial injections compared to untreated sand. APMDES-treated sand biocemented using three injections of bacteria and cementation media gained the same strength as seven injections. Biomineral gain of APMDES-treated sand was similar compared to untreated sand, which shows calcium accrual in the structure may be influenced by additional factors, such as the distribution of calcite, differences in the calcite precipitation patterns, and morphology. Overall, incorporating APMDES treatment can potentially improve the efficiency and sustainability of MICP by spatially controlling biomineralization.
Analysis of energy and savings of using ground loop or steam to change temperature of the bulding heat pump loop in Norm Asbjornson Hall
(Montana State University - Bozeman, College of Engineering, 2023) Kuikel, Shraddha; Chairperson, Graduate Committee: Kevin Amende
The need for efficient and sustainable environmental conditioning systems in buildings has become increasingly important in the face of rising energy costs and environmental concerns. This thesis aims to assess the optimization of the control logic to maximize energy savings and costs associated with utilizing ground loop or steam to modify the temperature of a heat pump loop in ground source heat pumps (GSHP) in Norm Asbjornson Hall (NAH) building at Montana State University (MSU). The study begins by providing a comprehensive review of existing literature on GSHP systems, their working principles, and the various methods employed to alter the temperature of the heat pump loop. The research methodology involves determining the conditions under which it is economically viable to operate ground loops and/or a steam heat exchanger to maintain the heat pump loop temperature within a set operating range. This is done by deriving an equation that utilizes the coefficient of performance (COP) and entering water temperature (EWT) of the heat pump loop. Energy and cost analysis is then conducted to assess the energy efficiencies for different cases. The findings reveal that both steam and ground loops can effectively alter the temperature of heat pump loops, providing enhanced temperature control and increased energy efficiency. The analysis shows that each strategy does have important financial and environmental implications, nevertheless. Due to the equipment, infrastructure, and operational expenditures, steam injection is primarily utilized to raise the loop's temperature for heating mode only, and at extreme situations when the ground loop cannot provide enough energy to maintain the heat pump loop temperatures. However, compared to steam injection, ground loops, which can be used for both heating or cooling, offer significant energy savings and lower long-term maintenance costs, albeit needing a sizable initial investment. In summary, the thesis explores how to optimize control logic to save energy and costs using ground loop or steam to adjust building heat pump loop temperature. The study evaluates energy, cost, and environmental impact of the proposed control logic optimization approach. The findings aim to provide insights into informed decision-making regarding the adoption of this alternative method.
Forming properties of stretch broken carbon fiber for aircraft structures
(Montana State University - Bozeman, College of Engineering, 2023) Nold, Dalton Bradley; Chairperson, Graduate Committee: Dilpreet S. Bajwa; Douglas S. Cairns (co-chair); This is a manuscript style paper that includes co-authored chapters.
Continuous carbon fiber is known to be a superior material for its strength, stiffness, and high strength-to-weight ratio and is often incorporated in aerospace composites. A challenge, however, is that it's not versatile in forming deep drawn geometries, which require convoluted manufacturing techniques resulting in expensive components. To overcome this, a type of carbon fiber with a random discontinuous fiber alignment called stretch broken carbon fiber (SBCF) is proposed. SBCF has potential to form parts with complex geometries with comparable or better mechanical properties to that of continuous carbon fiber. Montana State University (MSU) developed its own version of SBCF manufacturing processes, and research is being conducted to understand how SBCF prepreg tows react to stretch drawing at elevated temperatures using aerospace-grade epoxy resin systems. Currently, several new methods have been proposed to rapidly test these materials. This research revealed that SBCF forms with greater ease than continuous carbon fiber and is expected to substantially reduce manufacturing times for aircraft structures. To comprehend the material's behavior, simple tensile tests were coursed to understand how gauge length and temperature affected the peak loads when compared to continuous carbon fiber. It was discovered that on average, SBCF experienced stresses that were ten times less than continuous fibers. Additional tensile tests were conducted at elevated temperature to determine the true stress versus true strain. These tests are particularly important because they represent the material's most accurate mechanical properties. The results led to the discovery that SBCF experienced strain softening behavior. Furthermore, a series of forming tests using a novel "forming fixture" revealed that increasing the gap lowered the peak forming loads while the plunger geometry had little to no effect on peak forces at both room and elevated temperatures.

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