Doctor of Philosophy, University of Akron, 2007, Polymer Science

Significant interest in nanotechnology is stimulated by the fact that materials exhibit qualitative changes of properties when their dimensions approach nanometer scales. Quantization of electronic, optical, and acoustic energies with nanoscale dimensions provides exciting, novel functions and opportunities, with interests spanning from electronics and photonics to biology. Characterizing the behavior of nanoscale materials is critical for the full utilization of such novel properties, but metrology for nanostructures is not yet well developed. In particular, mechanical properties of nanoscale particles or features are critical to the manipulation and stability of individual elements, yet changes in mechanical and thermodynamic properties in nanostructured materials create complications in fabrication. This thesis involves the application of Brillouin light scattering to quantify and utilize confinement induced vibrational spectra to understand phononics and elastic properties of nanostructured materials. Measurement and proper interpretation of acoustic waves in polymeric, inorganic, and biological nanostructures provides information about elastic properties and self-assembly. Brillouin light scattering was used to study the vibrational spectra of two-dimensionally confined photoresist and silicon oxide nanolines and three-dimensionally confined poly(methyl methacrylate) spheres and spherical-like viruses. These applications extend the capabilities of Brillouin from characterization of thin films and well-defined spheres to more complex structures. Acoustic waves propagating along the polymeric and silicon oxide lines allowed determination of modulus and its anisotropy. An unexpected acoustic mode was identified in the spectra from nanolines that provided a means to measure mechanical anisotropy. In polymeric lines as narrow as 88nm, neither a change in elastic properties relative to bulk elastic values nor anisotropy in elastic constants was observed. The acoustic (open full item for complete abstract)

Doctor of Nursing Practice, Mount St. Joseph University , 2024, Department of Nursing

Mechanical ventilation is a lifesaving therapy frequently used in intensive care units for critically ill patients. More than thirty percent of critically ill patients will require mechanical ventilation. Continuous sedation often accompanies mechanical ventilation to promote comfort and compliance with the ventilator. The longer the patient remains on a mechanical ventilator, the more of a risk the patient is apt to develop ventilator-associated events, pneumonia, acute respiratory distress syndrome, immobility, and psychosis. This can have a significant impact on the patient's overall outcome, length of stay, and risk for mortality. Early extubation is shown to be effective in the prevention of these associated risks. The use of light sedation, daily awakening trials with coordinated breathing trials have a significant positive impact on the critically ill patient. The goal of this Doctor of Nursing Practice (DNP) evidence-based practice quality improvement (EBP-QI) project was to improve patient outcomes by implementing a standardized spontaneous awakening trial with a coordinated breathing trial protocol. The Johns Hopkins Nursing Evidence-Based Practice Model and the American Association of Critical-Care Nurses (AACN) Synergy Model for Patient Care were the evidence-based practice model and theoretical framework used to guide this project. This project's outcome was to decrease ventilator days and hospital length of stay. 64 nurses participated in the new protocol education. While this study did not show a significant reduction in either ventilator days or hospital length of stay, a significant increase in protocol compliance and nurse comfort in initiating a spontaneous awakening trial was seen. These improvements can lead to a decrease in ventilator days and hospital length of stay overtime.

Master of Science, Miami University, 2023, Mechanical and Manufacturing Engineering

Balancing creativity with a structured approach in engineering design poses a critical challenge, necessitating optimization of each stage to aid in efficiently creating superior products. Functional analysis, a systematic approach defining the design problem, enables comprehensive exploration of the design space. However, critics argue that it requires too many resources, restricts creativity, and imposes high demands on design teams. The goal of this research is to enhance the effectiveness of functional analysis by integrating theories from cognitive research and human-centered design. The proposed method, Natural Cognitive Flow Functional Analysis (NCFFA), aims to promote designers' creative freedom, maintain the quality of the function model, and be accessible to engineering students and professionals alike. A between-subject study involving novice engineers evaluated the effectiveness of NCFFA. Although determining the full effectiveness of NCFFA in terms of enhanced creativity and reduced effort proved challenging, the study found marginal improvement in designers' Flow State, suggesting the potential merit of the NCFFA method for enhancing the designer experience during functional analysis. The study highlights the benefits of incorporating cognitive research and human-centered design principles into functional analysis and paves the way for further research to refine the structured design process.

Doctor of Philosophy, The Ohio State University, 2023, Mechanical Engineering

Metamaterials are deliberately architected artificial materials that can achieve unconventional properties not observed in nature, showing potential for various applications. Mechanical metamaterials are a new branch of metamaterials using geometry designs to control mechanical properties such as stiffness, deformation, and energy absorption. To date, most of the research on mechanical metamaterials considers an array of unit cells distributed in a uniform pattern, and the properties of those mechanical metamaterials are restricted by the unit cell structure. By introducing multiple unit cells into the array with non-uniform patterns, a much wider variety of mechanical properties become possible. However, such non-uniform mechanical metamaterials with extensive design domains bring challenges to the design, especially when specific target properties are desired. Motivated by the development of deep learning, we develop a framework based on feedforward neural networks (FNN) to systematically explore a large design domain of non-uniform mechanical metamaterials with nonlinearity in material, geometry, and boundary condition, realizing the mechanical response curve predictions of non-uniform patterns and the inverse designs for given target response curves. But for conventional mechanical metamaterials, their properties are significantly confined by the original geometries and lack in-situ tunability. Thus by a direct ink writing (DIW) technique, we combine hard-magnetic soft materials (MSMs) and hard-magnetic shape memory polymers (M-SMPs), which demonstrate superior shape manipulation performance by realizing reprogrammable, untethered, fast, and reversible shape transformation and shape locking in one material system, to develop magneto-mechanical metamaterials that are capable of shifting between various macroscopic mechanical behaviors such as expansion, contraction, shear, and bending under cooperative thermal and magnetic actuation, enabling wide-range i (open full item for complete abstract)

PHD, Kent State University, 2023, College of Arts and Sciences / Department of Chemistry and Biochemistry

Supramolecular Chemistry has become a versatile and dynamic field for drug delivery, catalysis, sensing, and protein targeting. It is based on molecular recognition which is the non-covalent interaction or intermolecular force (IMF) between the host and the guest with high affinity and specificity due to proper fitting. The IMF like H-bonding, Van der Waals forces, electrostatic and/or hydrophobic interaction are considered responsible for the proper fitting on the host cavity, but they lack the direct methods to precisely gauge the assembly/disassembly pathways of noncovalent force due to rapid motions of the molecules. Here, we used single-molecular force spectroscopy to directly measure the intermolecular mechanical force (IMMF) between the different hosts and the guests as well as small molecules. We found that the IMMF of cucurbit[7]uril (CB7) as host and charged adamantane as a guest was greater than neutral adamantane. From this study, we concluded that CB7 is a good host in drug delivery and sensing. However, when we changed the host and guest from CB7 to β-cyclodextrin (Me-β-CD/β-CD) and adamantane to cholesterol, respectively, we found that the IMMF between the β-CD and cholesterol depends on the orientations of the cholesterol inside the host cavity. We also found that the stability of the Me-β-CD-cholesterol complex was greater than the β-CD-cholesterol complex. In addition to the IMMF of host-guest pairs, we also measured the IMMF between two cholesterol molecules which is comparable to the stability of DNA secondary structures and the IMMFs of dimeric cholesterol complexes were dependent on the orientation of the interaction. By looking at the IMMFs, it tells that β-CD can easily solubilize the cholesterol plaque inside the artery. These results demonstrate that the IMMF can serve as a generic and multipurpose variable to examine noncovalent interactions among small molecules.

Master of Sciences (Engineering), Case Western Reserve University, 2022, Materials Science and Engineering

The effects of changes in process parameters, heat treatment, build orientation, and resulting defects on fatigue behavior of selective laser melting-processed AlSi10Mg have been determined. Samples were prepared under distinct P-V parameters and heat treatments for the following classifications: A- nominal with SR+HIP+T6, B- large defects with SR+HIP+T6, G- small to medium defects with SR+HIP+T6, D- many defects with SR+HIP+T6, E- large defects with SR+T6, and F- small to medium defects with SR+T6. Fatigue crack growth (FCG) testing of bend bars and high cycle fatigue (HCF) fatigue testing of cylindrical samples occurred at a stress ratio R = 0.1 and 20 Hz according to appropriate ASTM standards. This is reviewed along with ASTM-standardized tension testing of cylindrical samples. Increased defects typically reduced UTS, ductility, and fracture toughness particularly in the Z orientation. The S-N performances of X/Y orientation were improved or similar to the Z orientation in HCF as a result of having smaller or similar fatigue-initiating defect sizes, that were quantified for all failed S-N samples. HIP-processing generally reduced fatigue-initiating defects sizes and improved most S-N performances. Compared to SLM AlSi10Mg from literature, the nominal (A) build had an increased HCF performance. HCF sample life was estimated by using fracture surface defect measurements and FCG data obtained for those process conditions.

Master of Sciences, Case Western Reserve University, 2020, Physics

In this thesis we explore mechanical analogs of electronic topological insulators. We develop continuum models for the mechanical instability and spontaneous symmetry breaking for monolayer antimonene and bilayer graphene. We find that walls form between domains corresponding to different symmetry breaking minima. These domain walls are solitons in our model. Perturbations about the symmetry breaking equilibria propagate as waves with a gapped dispersion in the bulk but there is a gapless mode with linear dispersion that propagates along the domain wall in a manner reminiscent of the electronic edge modes of a topological insulator. We establish that monolayer antimonene is a mechanical topological insulator by demonstrating a mapping between our continuum model and an underlying Dirac equation of the symmetry class BDI which is known to be a topological insulator in one dimension and a weak topological insulator in two dimensions. Following a similar argument we expect that bilayer graphene as well is a weak topological insulator in two dimensions. We surmise that the effects studied here (namely low scale symmetry breaking, strain solitons and gapless edge modes) are not limited to antimonene and bilayer graphene but are common features of two dimensional materials.

Master of Science, The Ohio State University, 2017, Materials Science and Engineering

Hot stamped boron steels, such as Usibor® 1500, have been increasingly used in automotive structural components for light-weighting and impact resistance. Classified as an ultra-high strength steel, these alloys have superior strength with tensile strengths exceeding 1500 MPa. The rapid heating and cooling thermal cycle during resistance spot welding can significantly alter the martensitic base metal microstructure, resulting in formation of coarse-grained and subcritical heat-affected zones (CGHAZ and SCHAZ) with inferior mechanical properties. The martensitic CGHAZ is adjacent to the weld nugget and experiences the most time above the AC3, which allows for austenite grain growth. The SCHAZ is next to the unaffected base metal and does not reach the AC1¬ during welding, thus the base metal microstructure is over-tempered into cementite and ferrite. The present research aims at developing the fundamental knowledge of plastic deformation and fracture behaviors of ultra-high strength steel resistance spot welds. As a resistance spot weld comprises highly inhomogeneous microstructure, the overall research approach is based on studying the local (or microstructure-dependent) mechanical properties for individual regions in the weld as well as their interactions with weld geometry on the deformation behavior. Specifically, optimal welding parameters are determined to produce welds of appropriate nugget diameter for 2T Usibor 1500 with a gauge thickness of 1.5 mm. Micro-hardness mapping and metallographic analysis allow for characterization of the weld metal, CGHAZ, SCHAZ, and base metal of the spot weld. Quasi-static tensile testing with digital image correlation (DIC) is used to determine the local stress-strain behaviors of each region using bulk microstructural samples created in a Gleeble® thermal-mechanical simulator. Conventional and innovative resistance spot weld mechanical testing methods are used to generate more knowledge on the deformation of joints un (open full item for complete abstract)

Doctor of Philosophy, The Ohio State University, 1987, Graduate School

Master of Science, University of Toledo, 2016, Civil Engineering

The motivation of this research originates from the hypothesis that the sinkhole occurrences in the karst areas are significantly affected by the mechanical behavior of geomaterials, chemical dissolution, hydrological transport and scenarios. The development and formation of sinkholes is strongly dominated by the geo-mechanical characteristics of soil and rock behavior complicated by the chemical interaction and hydraulic transport processes. Sinkholes formed in soils can be sudden and catastrophic in nature and involve many intricate processes which have not yet been assessed properly. This thesis presents preliminary results of an ongoing research focusing on mechanical and coupled hydro-mechanical modelling approaches, aimed to understand the diverse and intricate mechanisms behind the formation and development of cover-collapse and cover-subsidence types of sinkholes. The feasibility of the geomechanics approach of the sinkholes, understanding the critical factors and mechanisms involved in the formation of sinkholes and their deformation characteristics has been assessed using FLAC 2D. First, a parametric study was conducted in order to examine the effects of shape and size of the cavity, overburden thickness and pressure related to vertical stress and deformation. Larger sizes of the cavity and higher overburden pressures cause higher deformation at the cavity resulting in sinkhole development. Similarly, shape of the cavity is also an influential factor inducing sinkhole formation. Circular cavities are found more stable than the square and rectangular cavities. Second, the FLAC was also used to model the behavior of geomaterials around a cavity in various potential water drawdown scenarios. Deeper lowering of the water table was found to cause larger deformation. Moreover, the influence of the slow and rapid drawdown of the water is studied thoroughly, the results show that the rapid drawdown induces fast creation of sinkholes. However, slow drawdown has li (open full item for complete abstract)

Bachelor of Science (BS), Ohio University, 2015, Biological Sciences

Osteoporosis is a disease characterized by a decline in bone strength leading to an increased risk of fracture, but no clinical device measures bone strength. Bone strength is strongly associated with bone stiffness (EI), but no clinical device measures EI either. Mechanical Response Tissue Analysis (MRTA) is being developed to measure EI in human ulna bones in vivo. Bone EI depends strongly on bone interosseous diameter (ID), and cortical porosity (CP) has been proposed for assessing fracture risk. This project compared the accuracies with which ulna bending strength was predicted by CP, ID, and EI in 35 cadaveric arms from men and women ranging widely in age (17-99 yrs.) and BMI (13-40 kg/m2). ID was obtained by computed tomography (CT). Ulna EI was measured noninvasively by MRTA on intact arms, while EI and bending strength were measured on excised ulnas by the gold standard method, Quasistatic Mechanical Testing (QMT), which cannot be employed in vivo. ID and CP were obtained in fractured ulnas by micro-computed tomography (µCT) by ImageJ using Avizo® 3D models to locate the endosteum. Simple and forward stepwise multiple regressions revealed that CP was the least accurate predictor of bending strength (SEE≥235N). ID as more accurate (SEE≤163N, p=0.02). Accuracies of predictions by ID from CT and µCT images were indistinguishable (p=0.35). Accuracies of predictions by EI measured by QMT and MRTA (SEE≤91N) were more accurate than CP and ID alone or together (p≤0.02) and indistinguishable from one other (p=0.12). Age was the only predictor to explain any (1%) variance not explained by EI. No model with >2 predictors was significant.

Doctor of Philosophy, University of Toledo, 2014, Engineering

Bio-nanocomposites have recently attracted much interest in the field of bioengineering due to their exceptional chemical, mechanical and biological properties. On one hand, biopolymers such as chitosan have low mechanical properties which have to be improved by diverse methods in order to utilize them for medical applications. On the other hand, biocompatibility of the final material is critical for tissue engineering. Thus, fabricating and designing bio-nanocomposites with biocompatibility, biodegradability and improved mechanical properties are critical for next generation of implantable bone tissue biomaterials. Measurement of cell mechanical properties is also a timely and important topic in mechanical and bioengineering viewpoints. Previous studies have indicated there are some differences between healthy and cancerous cells which can be led to diagnosis of cancers. One of the main purposes of this dissertation is to improve the mechanical properties of chitosan using different methods of fabrication such as formation of cross-linking and addition of nanoparticles and tubes as reinforcement into chitosan matrix. In this study, Tripolyphosphate was used to cross-link between amino group in chitosan and phosphate groups of tripolyphosphate molecules. Micro- and nano- mechanical measurements showed that cross-linking chitosan would improve elastic modulus in both macro and nano scales. Atomic force microscopy based nanoindentation indicated that cross-linking decreased ductility of samples. In addition, surface morphology and material behavior under the applied loads were explored. A new method of measuring cell mechanical properties was introduced and the elastic modulus of two different cell lines at different cell regions was estimated using Hertz model. This novel method did not require any specific substrate treatment or cell fixation. The elastic modulus was measured at cell nucleus and cytoskeleton parts in human amniotic fluid stem cells and murine ost (open full item for complete abstract)

Master of Science in Engineering (MSEgr), Wright State University, 2013, Biomedical Engineering

Direct Mechanical Ventricular Actuation (DMVA) is a non-blood contacting cardiac assist device that augments ventricular function. The purpose of this study was to determine if a volume-regulated “hand pump” drive system and a pressure-regulated “switch tank” drive system provide equivalent levels of cardiac support. Canine (n=2) and swine (n=4) were instrumented for hemodynamic monitoring and intravascular echocardiography. DMVA support was assessed during both severe heart failure and fibrillation. Pump function was evaluated using hemodynamic measures to calculate stroke work. Myocardial function was assessed using echocardiographic speckle tracking to quantify strain rate. Results were compared between groups using paired t-tests. There were no significant differences in either pump function or myocardial strain rates between the hand pump versus switch tank during support of either the failing or fibrillating heart. These results suggest functional equivalency between the two drive system mechanisms that supports development of an automated volume-regulated system, with its corresponding benefits in reduced size, portability, and potential user-friendly control.

Master of Science (MS), Ohio University, 2010, Biomedical Engineering (Engineering and Technology)

Actuation is one of the fundamental aspects of robots. Optimization of a robotic system poses a complex problem for engineers. For developing robots that mimic biological systems, the robot actuation problem becomes more complicated because of stringent limitations on space and power output. It is hypothesized that a system can be designed which would allow a rotating capstan to act as a mechanical amplifier when a flexible member such as a cord or rope is wrapped around it. When a tension is applied to the end of the cord pointing in the direction of the capstan's rotation, friction will be transferred to the cord and the tension will effectively be amplified. Experimentation was performed to validate a traditional assumption for how the dynamics of the system should work. The capstan equation was found to be only a rough estimation of the behavior of the system. A new equation was formed by combining known curves and fitting them to the data. Simulation of the new equation provides an initial insight into the behavior of a combined capstan amplifier system.

Bachelor of Science (BS), Ohio University, 2013, Biological Sciences

Fracture occurs when mechanical loading exceeds bones strength. The National Institute of Health defines osteoporosis as a skeletal disorder characterized by decreased bone strength, but no medical device measures bone strength directly in vivo. Bone stiffness is strongly associated with bone strength, but no clinical method measures bone stiffness in vivo, either. Quasistatic Mechanical Testing (QMT) is the reference gold standard method for directly measuring the stiffness and strength of bones, but it can only be employed on excised bones and bone samples. Mechanical Response Tissue Analysis (MRTA) is a minimal-risk, non-invasive, radiation-free technique for measuring the bending stiffness of certain long bones, such as the ulna, in humans in vivo. MRTA was originally developed at Stanford University in the 1980's, but limited information has been published about its accuracy. Ohio University is further developing an MRTA device and the purpose of the research reported in this thesis was to validate the accuracy, precision, and repeatability of this device by comparison to QMT. The stiffness of standard and custom artificial human ulnas (N = 39) with -10% to +10% excess glass fill in the glass-epoxy composite emulating cortical bone (Pacific Research Laboratories/Sawbones, Vashon, WA) were measured by MRTA and QMT in 3-point antero-posterior bending with proximal support by an articulating vertical Sawbones® humerus and distal support by the anterior distal radio-ulnar articular surface on a steel block. The load was applied at the mid-point of the posterior border. The precision and repeatability, respectively, of stiffness measurements were calculated without and with dismounting of ulnas from the humerus between repeated measures. Fifteen of the artificial human ulnas were then fractured by QMT under the same support conditions to determine the relationship between bending stiffness and strength. Results demonstrated that in our hands MRTA and (open full item for complete abstract)

Master of Science in Aerospace Systems Engineering (MSASE), Wright State University, 2024, Mechanical Engineering

The development of high order numerical schemes has been instrumental in advancing computational fluid dynamics (CFD), particularly for applications requiring high resolution of discontinuities and complex flow phenomena prevalent in high-speed flows. This thesis introduces the Pade-ENO scheme, a high-order method that integrates Essentially Non-Oscillatory (ENO) techniques with compact Pade stencils to achieve superior accuracy, up to 7th order, while maintaining stability in harsh environments. The scheme's performance is evaluated through benchmark tests, including the advection equation, Burgers' equation, and the Euler equations. For high Mach number flows, such as the sod shock tube the Pade-ENO method demonstrates its ability to resolve sharp gradients and discontinuities with no smoothing required. Numerical results highlight the scheme's robustness and its potential as a powerful tool for high-speed aerodynamic simulations, paving the way for future advancements in CFD modeling.

Doctor of Philosophy (Ph.D.), University of Dayton, 2024, Electrical and Computer Engineering

Additive manufacturing (AM) technology is rapidly advancing across diverse fields. For instance, the use of robotic arms in various AM processes has led to significant gains in printing flexibility and manufacturing scalability. However, despite these advancements, there remains a notable research gap concerning the mechanical properties of parts 3D-printed with robotic arms. This study focuses on developing a robotic fused filament fabrication (FFF) 3D-printing process with a layer resolution of 50 μm to 300 μm. The impact of the robotic printing process on the mechanical properties of printed parts is investigated and benchmarked against a commercial FFF 3D printer. In addition, we propose a novel tool path that can vary contour layer thickness within an infill layer to improve mechanical strength by minimizing air gaps between contours. SEM images suggest that this new tool path strategy leads to a significant reduction in the fraction of the void area within the contours, confirmed by a nearly 6% increase in the ultimate tensile strength. Furthermore, a novel strategy for non-planar contours is proposed, specifically designed for thin-shell 3D models. This approach aligns tool paths parallel to the Z-axis, organized into triangular segments, and utilizes planar slicing techniques. The method involves segmenting the point cloud and systematically printing non-planar contours on top of the planar contours. Axial compression testing reveals that samples produced using this strategy exhibit mechanical properties comparable to those of conventional 3D printing. However, distinct fracture patterns are observed: in conventional 3D-printed samples, fractures occur on both inner and outer surfaces, while in non-planar printed samples, fractures are confined to the inner surfaces (planar contours) and do not propagate to the outer non-planar contours. This demonstrates the potential of non-planar printing for improved structural integrity.

PhD, University of Cincinnati, 2024, Engineering and Applied Science: Materials Science

The welded austenitic 304 / 304L Stainless Steel (SS) Spent Nuclear Fuel Dry Storage Canisters (SNFDSCs), either newly built or the in-service ones, are facing a looming and insidious problem of Chloride Induced Stress Corrosion Cracking (CISCC). The construction of these large structured austenitic SNFDSCs involves welding which results in them undergoing the adverse phenomenon of sensitization at the welded areas making the newly built welded austenitic SNFDSCs susceptible to intergranular stress corrosion cracking. Furthermore, in the case of in-service canisters situated near marine environment, the presence of chloride salts in the atmosphere aided by the tensile residual stresses present at the welded areas led to crack formation at the heat affected zones of the susceptible weldments due to CISCC. Therefore, to prolong the service life of in-service SNFDSCs and to avoid the catastrophes involved in their failures, long term reliable cost-effective in-situ repair methods such as Cold Spray (CS), Laser-Assisted Cold Spray (LACS), and Additive Friction Stir (AFS) deposition techniques have been considered as plausible solutions by the nuclear industry for repairing the CISC-Cracks in the existing canisters. However, the corrosion behavior (CB) of 304L SS material deposited through these three processing techniques remains unexplored. Hence, a part of this dissertation research work aimed at studying the microstructural, mechanical, residual stress (RS), and most importantly, the CB of 304L SS material deposited by these three processing techniques along with that of the sensitized 304L SS material, which revealed that the sensitized, CS, LACS, and AFS 304L SS materials had inferior corrosion and/or residual stress properties owing to the differences in their microstructural characteristics from that of the bulk 304L SS material. Therefore, to improve the corrosion properties of these four different 304L SS materials having distinct micro (open full item for complete abstract)

Master of Science (M.S.), University of Dayton, 2024, Mechanical Engineering

The goal of this work is to analyze and characterize solid granular media in high temperature CSP applications. This work expands on commercially available Discrete Element Method (DEM) modeling software, Aspherix®, through development of two calibration templates designed to mimic both the experimental rigs for the slump test and rotary kiln discussed in this thesis. Whereas, designed experimental rigs were developed to isolate desired frictional behaviors in three different material types (CarboBead HSP, CarboBead CP, and Granusil) for temperatures varying from 25°C – 800°C. Additionally, improvements were made upon the previously constructed rotary kiln to facilitate high temperature testing experimentally.

Master of Science, The Ohio State University, 2006, Graduate School