Master of Science in Engineering, University of Akron, 2018, Mechanical Engineering

Recently, developments in automotive industries have increased competition. So, the design and development of new products have become more time sensitive. But an equally important aspect is the durability and reliability of new products. Currently, the reliability of products is tested and examined using traditional laboratory methods. In this traditional approach, the products are tested until failure, which is usually a costly and time-consuming process. Additionally, this approach increases the time from design to market. Reducing the testing duration of new products will reduce the product development cost and time to market. Therefore there is an increase in employing Accelerate Life Test (ALT) methods by many companies. ALT is the method of testing a product sample by applying more severe environmental conditions than normal conditions. Although cost and time can be reduced by this method, the method is insufficient in many cases because it often does not accurately determine the root cause of potential failures. Consequently, this need has given rise to the development of prediction models to enable a better understanding of product reliability. According to many studies, the main reason for the failure of mechanical components is the loss of material on the surfaces, in other words, wear. Previous research efforts have created a platform for wear simulation by combining Finite Element Analysis (FEA) with mathematical wear equations. This research is focused on reducing the wear simulation time by using an axisymmetric model and developing a mathematical equation in which the wear on the contacting surfaces in relative motion can be calculated by simulating the wear on only one surface in contact. This approach should make the FEA model more time and cost efficient. In this research, a critical factor (wear rate) is determined from experimental data, i.e., wear tests. Based on these results, the local wear is firstly calculated and then integrated over (open full item for complete abstract)

Committee: Gary Doll (Advisor); Shao Wang (Advisor); Manigandan Kannan (Committee Member) Subjects: Educational Tests and Measurements; Engineering; Experiments; Materials Science; Mechanical Engineering

MS, University of Cincinnati, 2023, Arts and Sciences: Geology

Sauropods are extraordinary animals: they surpassed all other clades of herbivorous dinosaur in diversity or body-mass but, maybe more astonishing, they are terrestrial, mega-herbivore r-strategists. The abundant sauropod offspring constituted a large share of biomass in Mesozoic ecosystems and shaped trophic dynamics of Jurassic and Cretaceous ecosystems. However, we know little about the ecological niches occupied by both adult and juvenile sauropods owing to the sparse fossil record of sauropod skulls, particularly juvenile skull elements. Dietary niches are a central aspect of ecology dictating not only the exploitation of resources, but also the animals' habitat-use. A collection of teeth attributed to the Late Cretaceous titanosaur Rapetosaurus krausei, Curry Rogers & Forster, 2001, includes specimens spanning a wide ontogenetic range which document variation in tooth morphology throughout life history. Combined with evidence from the known record of Rapetosaurus cranial material, including a hatchling dentary, I use the teeth to test for changes in feeding strategy throughout ontogeny. Tooth morphology in Rapetosaurus changed both in the shape of unworn teeth and in complexity of wear throughout ontogeny. The morphology of sauropod teeth is commonly designated as either peg-like or spatulate-like; broader spatulate-like teeth are considered the more primitive state, with narrower peg-like teeth considered an adaptation for non-selective bulk-feeding on plant material. The size distribution of spatulate-like teeth within our dataset suggests that Rapetosaurus replaced the spatulate-like dentition found in the hatchling with a peg-like dentition during ontogeny. Tooth wear also differs within the sample and can be classified into 14 distinctive wear-types, some of which are known from other sauropod taxa. I qualitatively ascertained the validity of these wear-types with the use of observer-independent, semi-landmark-based 3D-geometric morphometrics. The framewo (open full item for complete abstract)

Committee: Joshua Miller Ph.D. (Committee Chair); Kristina Curry Rogers Ph.D. (Committee Member); Brooke Crowley Ph.D. (Committee Member) Subjects: Paleontology

Master of Science, Miami University, 2021, Mechanical and Manufacturing Engineering

Polytetrafluoroethylene (PTFE) is commonly used as a solid lubricant due to its ultralow friction coefficient (µ=0.04~0.20). However, its high wear rate (K~10-4 mm3/Nm) motivated researchers to study its composites to reduce wear. While many fillers can produce up to 1000 times lower wear, certain α-alumina can lower its wear rate up to 10,000 times. Robust tribofilm generation due to tribochemistry is likely the cause of this ultralow wear behavior. The filler particle porosity along with the filler material is considered behind this enhanced tribofilm generation. This study evaluated the effect on composite wear rate due to the ratio of its filler and countersurface hardness. During this investigation,additional ultralow wear low friction PTFE composites were discovered. This study revealed the friction coefficient of PTFE-Cr against brass 260 countersample to be around half that of ultralow wear PTFE α-alumin's (µ=0.12 vs µ=0.2~0.25) while delivering similar wear properties as PTFE α-alumina. It has also revealed that, within the same fillers, a lower wear rate can be distributed around a certain region of hardness ratio of filler and countersamples.

Committee: Mark Sidebottom Dr. (Advisor); Timothy Cameron Dr. (Committee Member); Zhijiang Ye Dr. (Committee Member) Subjects: Mechanical Engineering

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

Committee: Not Provided (Other) Subjects: Engineering

Doctor of Philosophy, University of Toledo, 2011, Bioengineering

Relative motion at interacting implant surfaces will generate wear debris over time. Bio-tribological tests serve as an effective pre-clinical tool to investigate device wear characteristics. Wear debris evaluations for artificial discs are done in simulators using the currently published ASTM/ISO loading profiles. However, these tests can primarily compare wear related parameters of one disc design against another as opposed to an in vivo scenario. Additionally, these experiments are time consuming, expensive and labor intensive procedures. Current wear testing standards for artificial discs do not account for parameters such as the influence of anatomic structures and variations in the surgical procedures for disc placement. However, appropriate parametric mathematical modeling may help assess the contributions of these parameters to implant wear. The objective of this study is to address the above mentioned factors and to simulate in-vivo wear parameters as far as practicable. In this approach, the wear phenomena of the total disc replacement (for two different designs – metal on metal and metal on polymer) placed in a ligamentous functional spinal unit (FSU), as opposed the disc alone analyses conducted previously by other researchers was simulated. The models were further modified by sequential addition and removal of spinal structures in order to understand the role of each element with respect to the wear outcome. Furthermore, the effect of the implant placement was studied. This was followed by comparative analyses of load versus displacement control test methodology. A significant difference was noted between the implanted and standalone condition. The standalone test cases were in agreement with the published literature, while the implanted scenario replicated some of the retrieval failure modes. Lift-off at the device interface was observed at the implant interface which was found to be a function of facets and muscle forces. This phenomenon was also re (open full item for complete abstract)

Committee: Vijay K. Goel PhD (Advisor); Arunan Nadarajah PhD (Committee Member); Constantine Demetropoulos PhD (Committee Member); Ioan Marinsecu PhD (Committee Member); Lesley Berhan PhD (Committee Member) Subjects: Biomechanics; Biomedical Engineering; Biomedical Research; Biophysics

Master of Arts, University of Akron, 2008, Family and Consumer Sciences-Clothing, Textiles and Interiors

George Stavropoulos, a New York fashion designer, built a multi-million dollar business on his signature, floating chiffon dresses. His self-titled label produced eveningwear and daytime styles for the wholesale, ready-to-wear market, from 1961 to1991. While he was known for his use of chiffon, Stavropoulos also created notable designs in lace, lame, suede, and taffeta. Stavropoulos, born in Greece, believed in classic design and found inspiration in the simplicity of ancient Greek sculpture. Renowned for his innovative draping techniques, Stavropoulos created every piece in his collection and produced the entire line in his 57th Street atelier. For each spring and fall runway presentation, Stavropoulos created about one hundred designs and held his shows at the luxurious Regency Hotel, in Manhattan. Buyers from the most important stores in New York attended each show, as well as socialites and celebrities. Stavropoulos initially became know for dressing Lady Bird Johnson during her White House years and created looks for other popular figures throughout his career. Fiercely independent, Stavropoulos did not participate in the licensing agreements popular with other designers of his time nor did he join the Council of Fashion Designers of America (CFDA). Stavropoulos believed in his own fashion philosophy and refused to adhere to the ephemeral nature of fashion, creating sophisticated designs that were innovative rather than shocking or avant-garde.

Committee: Virginia Gunn (Advisor) Subjects: Art History; Design; Fine Arts; Home Economics; Marketing; Museums; Textile Research

Master of Science, The Ohio State University, 2013, Mechanical Engineering

Wear models developed for gears often employ Archard's wear equation, which states that the change of wear depth with sliding distance is proportional to contact pressure. The constant of proportionality, the wear coefficient, represents all other contact parameters with potential impact on wear, ranging from lubricant parameters, surface conditions and operation conditions to material type and hardness. As such, application of the Archard's equation to gear wear problems requires that the wear coefficient be defined empirically. This study aims at quantifying the influence of various contact parameters on the wear coefficient such that this dependence on empirical means can be minimized. For this purpose, a wear model of point contacts formed by surfaces in relative sliding is developed. The model combines a contact pressure formulation and the Archard's wear equation to predict the accumulation of wear on contact surfaces. A family of two-disk roller contact experiments are simulated using this model and the wear coefficient value that results in a good match between the measured and predicted wear profiles is determined for each test. With simulations of tests performed at various speeds, normal forces (contact pressures), oil temperatures (i.e. viscosities), and surface roughnesses, impact of these contact parameters on the wear coefficient values is quantified. A regression analysis of the wear coefficient values as a function of dimensionless force, speed, viscosity and roughness parameters is carried out at the end to obtain an expression for the wear coefficient that includes these parameters.

Committee: Ahmet Kahraman (Advisor); Gary Kinzel (Committee Member) Subjects: Mechanical Engineering

Master of Science, The Ohio State University, 1971, Graduate School

Committee: Not Provided (Other) Subjects:

Master of Science, The Ohio State University, 2007, Graduate School

Committee: Not Provided (Other) Subjects:

Master of Science, Miami University, 2024, Mechanical and Manufacturing Engineering

The friction and wear properties of bilayer graphene on silicon substrate with diamond atomic force microscope tip were investigated using molecular dynamic simulation with three independent variables of tip velocity, temperature, and normal load. Based on isolated experimental results, it is determined that graphene friction is velocity, temperature, and normal load dependent. Velocity and normal load increase lead to positive friction correlations while temperature increase leads to negative friction correlations, thus leaving the mechanism to be determined. Combined studies reveal similar results, with each variable maintaining its isolated effect in chorus with the other utilized. Upon obtaining the contact area from these experiments it is evident that velocity and temperature change do not hold direct bearing on the contact area, rather that it is the normal load and size of the sliding surfaces that can fluctuate both contact area and friction in tandem. Hence, the mechanism with respect to velocity and temperature dependence of graphene friction is determined to be variation in interatomic potentials associated with interatomic interactions. Varying the contact area can increase or decrease the quantity of atoms in contact, therefore also having an impact on graphene friction.

Committee: Justin Ye (Advisor); Mark Sidebottom (Committee Member); Andrew Paluch (Committee Member); Timothy Cameron (Committee Member) Subjects: Engineering; Materials Science; Mechanical Engineering

Doctor of Philosophy, University of Akron, 2024, Mechanical Engineering

The rise of electric vehicles (EVs) has led to new engineering challenges for electric motors and new design opportunities for lubricants and tribological elements like bearings and gears. High power density EV motors require dual fluids: a high heat capacity, low viscosity coolant fluid and a highly effective lubricant capable of protecting ultra-high-speed bearings and gears. This dual fluid practice requires two different fluid systems (sumps, pumps, pipes, and filters) adding cost, weight and complexity. Compared to combustion engines, EVs fluids (oils and coolants) do not require similarly extreme high temperature capabilities. Thus, the opportunity exists to consider new fluids (coolants/lubricants) to enhance EV system performance. Towards this end, low viscosity, high heat capacity fluids such as water-based lubricants (WBLs) have gained popularity, as they can cool electric components and lubricate moving parts fulfilling the single fluid approach. However, WBLs have limitations such as low viscosity, evaporation, freezing point, microbiological growth, oxidation, corrosion, and high electrical conductivity. To mitigate these limitations, different additives such as ionic liquids, bio-based oils, and nanoparticles have been incorporated into WBLs. This has resulted in significant improvements in coefficient of friction and wear reduction. Limited literature is available on the rheological and tribological behavior of WBLs in steels, and the wear mechanisms for these lubricants are not fully understood. The proposed work aims to test different WBLs by characterizing their rheological properties and conducting tribological tests such as fretting and sliding experiments. Posttest analyses will be performed via SEM/EDX, XRD, and AFM to characterize the tribofilms and surface morphology. The results will be compared with traditional lubricants to gain a better understanding of the mechanisms and propose adjustments to current modeling tools. The study unders (open full item for complete abstract)

Committee: Christopher DellaCorte (Advisor); Yalin Dong (Committee Member); Nicholas G. Garafolo (Committee Member); Manigandan Kannan (Committee Member); Weinan Xu (Committee Member); Richard L. Einsporn (Committee Member) Subjects: Mechanical Engineering

Master of Science, Miami University, 2023, Mechanical Engineering

Unfilled PTFE has a low friction coefficient, but also a high wear rate (K~10-4-10-3 mm3/Nm). Different filler materials can reduce the wear rate of PTFE by ~104 against 304 SS. These ultra-low wear composites form a film between the sliding interfaces which lowers the wear rate. The film observed on the counterbody is known as transfer film. Recently three metal filler (Cr, Ti, Mn) particles were able to achieve ultra-low wear rate against Brass 260 but mixed performance against 304 SS. This discovery motivated to explore other countebodies such as Cu110 and Zn. The test showed high variation in friction coefficient and wear rate among different counterbodies. Hence the transfer film needed to be analyzed to find the relation between these fillers and counterbodies other than 304 SS. PTFE-Cr was chosen for this study as it showed the most variation among the counterbodies (~2× variation in μ and 1000× variation in wear rate). PTFE-Cr showed lowest wear rate against Brass 260 (K~7.1×10-9 mm3/Nm with desired transfer film properties: coverage (Lf~50 μm @ 50 m), thickness (~300 nm), surface energy (~35 mJ/m2), low friction coefficient(μ~0.2). Cu 110, 304 SS, and Zn coated steel showed abrasive wear resulted in high wear rate.

Committee: Mark Sidebottom (Advisor); Zhijiang Ye (Committee Member); Giancarlo Corti (Committee Member); Andrew Sommers (Committee Member) Subjects: Mechanical Engineering

Master of Science, The Ohio State University, 2023, Dentistry

Purpose: Currently there is no regulatory requirement or international standard for wear resistance of dental materials and therefore no need to test prior to market launch. The purpose of this study was to evaluate and compare the vertical and volumetric wear of milled (MPs) polymer infiltrated ceramic network (PICN) and printed polymer resin (PPs) with five opposing antagonists: human enamel (EN), lithium disilicate (LI), zirconia (ZR), milled PICN (MPa) and printed polymer resin (PPa). Additionally, the wear of the antagonists will be measured. Materials and Methods: Ten of each antagonist for a total of 50 EN, LI (IPS e.max CAD, Ivoclar Vivadent), ZR (IPS e.max ZirCAD MT, Ivoclar Vivadent), MPa (Crystal Ultra, Digital Dental Laboratory), and PPa (Crowntec for NextDent, NextDent, B.V.) were shaped into spherical heads and were tested against two disc shaped substrates, MPs (Crystal Ultra, Digital Dental Laboratory) and PPs (Crowntec for NextDent, NextDent, B.V.). Samples were tested in wear machine, with a third-body food substitute, loaded with a force of 20-70N at 1 Hz for 100 000 cycles. Maximum wear height and volume were measured for tail and head portions using software (WearCompare, Leeds Digital Dentistry). The area of the wear facet of antagonists were also measured and used to estimate height and volume loss of antagonists. Data were analyzed using two-way and one-way ANOVA followed by the Tukey's Multiple Comparisons post hoc test (α=0.05). Results: Significant differences in the amount of wear in substrates and in antagonists were found to be a result of the antagonist type, substrate type, and their interaction. Antagonists significantly affected the vertical abrasion (p=0.0011) and volumetric attrition (p=0.0134), which was seen by EN causing significantly more wear than PPa. Antagonists also significantly affected the vertical attrition (p=0.0012), where most antagonist groups were found to be significantly different. For differences in the s (open full item for complete abstract)

Committee: Scott Schricker (Advisor); Robert Seghi (Committee Member); Damian Lee (Committee Member) Subjects: Dentistry

Doctor of Philosophy (Ph.D.), Bowling Green State University, 2023, Photochemical Sciences

The interaction of molecules and materials with light can transform the chemical nature besides the physical phenomena. Investigation of these transformations for better cognizance of light mater interaction is significant. Chapter 2 will present a novel and new excited state reactivity of aryl maleimides that go through a [2+4] photodimerization utilizing visible light irradiation, instead of the established [2+2]-photodimerization. The [2+4] photodimerization of arylamides was established under both direct and sensitized conditions. Typically, light-mediated reactions proceed through electron transfer / energy transfer in case of sensitized (photocatalyzed) reactions. This new reactivity is investigated and reported using various photochemical and photophysical studies. Employing light as a green reagent for various transformations and development of novel green polymerization strategies is discussed in Chapter 3. Photoinitiators are relevant components in photopolymerization. Biomass derived and visible light activated photoinitiators are fascinating new technology when compared to fossil fuel derived UV-active photoinitiators. UV-light is hazardous and cause energy wastage. Chapter three will detail the synthesis of biomass derived photoinitiators that are effective in promoting polymerization under visible light irradiation. Based on photopolymerization and photophysical data, these new visible light active biomass derived photoinitiators are shown to have superior optical properties compared to conventional fossil fuel derived photoinitiators with similar functionality. Chapter 4 will detail the development of stabilizers for electronically dimmable eyewear, that features dye dopped liquid crystal (LC) scaffolds. The photodegradation of the LC materials were investigated and suitable stabilizers were evaluated to slow the degradation process. Chapter 5 will also highlight studies related to the photodegradable polym (open full item for complete abstract)

Committee: Jayaraman Sivaguru, Ph.D. (Committee Chair); Pavel Anzenbacher Ph.D. (Committee Member); Malcolm D. E. Forbes Ph.D. (Committee Member); Amy L. Morgan Ph.D. (Other) Subjects: Chemistry; Organic Chemistry

Doctor of Philosophy, The Ohio State University, 2023, Anthropology

Early Fort Ancient (c. 1000–1250 CE) sites in the Middle Ohio River Valley have classically been described as small-scale, egalitarian groups practicing maize agriculture. As some of the earliest farmers in the region, these groups represent a society at the transition to agriculture. In North America, the transition to agriculture is often linked with the rise of social complexity; however, the cause-and-effect relationship between these phenomena vary by region. At some sites, an increase in agricultural complexity precedes an increase in social diversity and complexity, whereas at other sites in the region, the reverse is true. Fort Ancient sites, in particular, have limited research on social relationships within sites, which leads to the question this dissertation addresses: In what ways did Fort Ancient groups exhibit social complexity during the transition to agriculture? This dissertation assesses social complexity in Fort Ancient groups using mortuary and bioarchaeological (dietary) analyses of two early Fort Ancient sites–Turpin (33HA28[19]) and Guard (12D29). Three additional questions are also addressed here: 1) To what extent did foraged food resources continue to be used in the Middle Ohio River Valley during early Fort Ancient?, 2) To what extent are Guard and Turpin likely to belong to the same cultural group?, and 3) To what extent do mortuary and bioarchaeological analyses support the conception of Fort Ancient cultures as egalitarian and lacking in social differentiation? Diet is analyzed through Dental Microwear Texture Analysis (DMTA), Occlusal Fingerprint Analysis (OFA), and dental caries, with comparisons to known isotopic data from the sites. These data provide both short- and long-term dietary information for individuals. To examine social relationships, diet is analyzed according to age, sex, and location of burial. Dietary data demonstrated that individuals at Guard and Turpin continued to use foraged food resources while also practicin (open full item for complete abstract)

Committee: Debbie Guatelli-Steinberg (Committee Chair); Robert Cook (Committee Co-Chair); Mark Hubbe (Committee Member); Luca Fiorenza (Committee Member); Christopher Schmidt (Committee Member) Subjects: Archaeology

Master of Science (MS), Ohio University, 2023, Civil Engineering (Engineering and Technology)

Tire particles (TP) are the largest source of microplastics in nature. However, the adsorption behavior of TP needs to be better understood. TP used in this study were generated from cryo-milling and aged with 30% nitric acid. Single and competitive adsorption isotherm experiments were conducted to investigate the potential of TP as carriers of heavy metals. Langmuir and Freundlich models were used to analyze adsorption data. Competitive adsorption demonstrated a reduction in the adsorption capacity of TP. The preference for lead to copper by TP was explained by the physical and chemical properties of the metals. The adsorption capacity was maximum at the pH range of 6-12 for lead, and for copper, it was pH 10. pH, zeta potential, FT-IR, and XPS results indicated that electrostatic attraction and surface complexation were involved in the heavy metal adsorption on TP.

Committee: Lei Wu Dr. (Advisor); Natalie Kruse-Daniels Dr. (Committee Member); Daniel Che Dr. (Committee Member); Guy Riefler Dr. (Committee Member) Subjects: Environmental Engineering

Doctor of Philosophy, University of Toledo, 2022, Engineering

Solid lubricants are materials with a layered crystal structure that provide lubrication in conditions where conventional liquid lubricants are unstable. They are used in extreme environmental and working conditions processes such as high and vacuumed pressure, cryogenic and high temperatures, corrosive and radiative environments, high loads and sliding velocity. Such conditions are mainly encountered in aerospace and marine applications. Some commercially used solid lubricants include 2D materials such as graphite, MoS2, h-BN. However, these materials lack good anti-wear properties and manufacture of lubricating composites where the lubricant is dispersed in a wear resistant matrix is the widely used method for increasing their wear resistance. Heavy metal doping that facilitates grain boundary strengthening and restricts the motion of dislocations across the grain boundary is also employed for improved wear properties. Another challenge of solid lubricants is the narrow operating range. Their lubricating properties drastically deteriorate with changes from specified operating parameters. Adaptive lubrication, where the lubricating mechanism changes with operating parameters is employed to increase the working range of these lubricants. This dissertation work focusses on understanding and improving the tribological properties of sputter deposited ZnO films. ZnO possess some desirable properties compared with existing solid lubricants. It has high-temperature stability, corrosion resistance, and radiation stability. Presently, commercially used solid lubricants are greatly influenced by these environmental parameters. Hence ZnO is a suitable candidate for developing solid lubricants with broad operating range. In this work, the effect of humidity and annealing on the coefficient of friction and wear life are primarily investigated. Pin-on-Disk tribo-test were conducted on sub stoichiometric ZnO films with silver, aluminium and nitrogen doping to understand its eff (open full item for complete abstract)

Committee: Ahalapitiya H. Jayatissa (Committee Chair); Adam Schroeder (Committee Member); Sorin Cioc (Committee Member); Lesley Berhan (Committee Member); Champa A. Jayasuriya (Committee Member) Subjects: Materials Science; Mechanical Engineering; Mechanics

Master of Dental Hygiene, The Ohio State University, 2021, Dental Hygiene

The use of activated charcoal has become prevalent in oral health products and concerns amongst dental professionals has risen on its safety. This study aims to determine if charcoal products are too abrasive on tooth enamel by comparing surface roughness changes after being subjected to toothbrush abrasion with charcoal and non-charcoal products. Twenty central incisors, collected from the Ohio State University restorative lab, were divided into four groups. Group one was brushed with Arm&Hammer Peroxicare toothpaste, group two was brushed with a mixture of Arm&Hammer Peroxicare toothpaste and activated charcoal powder, group three was brushed with charcoal powder mixed with water, and group four was brushed with plain water. The teeth were brushed with a toothbrushing machine for two-minute intervals which was repeated 60 times to mimic a month's worth of brushing. The specimens were subjected to profilometric analysis before and after brushing to determine surface roughness changes. Results were analyzed with descriptive statistics and one-way ANOVA. Results concluded that there was no significant difference on surface roughness values between groups, but there was a slight greater change in surface roughness changes with group two when comparing the mean RA change for each group.

Committee: Rachel Kearney (Advisor); Scott Schricker (Committee Member); Rebecca Henderson (Committee Member) Subjects: Dental Care; Dentistry

Doctor of Philosophy, University of Akron, 2021, Mechanical Engineering

In 2016 it was estimated that corrosion related costs were 3.4% of global GDP. Coatings are widely used for preventing or controlling corrosion. However, none of the currently used corrosion resistant coatings provides enough wear resistance for gears and bearing applications. Poor surface morphology of the corrosion resistant coatings cause increased wear and friction, resulting in early failure of the rolling element. Developing electrodeposited alloy coatings that promote synergy with additives used in gear and engine oils, while providing corrosion resistance can be a viable solution. Alloyed metals provides superior properties (like hardness, physical, chemical, magnetic) compared to pure metals, even at a nanoscale. Ni-W alloy was recently been reported to have unique contribution to mechanical, tribological and corrosion resistant performance. In addition, Ni was found to promote the formation of a thicker and durable lubricating layer. However, careful evaluation of in-service life of these alloy coatings are needed. Composite nanoparticles in many cases can also improve tribological performance of the component. Researchers have studied the effect of such nanoparticles on the tribological performance of oils. Both beneficial and detrimental effect of such nanoparticles has been reported. In this study NiW alloy and NiW-TiO2 composite coatings were electrodeposited on SAE 52100 steel coupons. Pulsed reversed current (PRC) electrodeposition technique is used due to its capability of producing more dense and uniform coating. Also, incorporating TiO2 nanoparticles on the NiW matrix is hypothesized to enhance the hardness and corrosion resistance. Both NiW alloy and NiW-TiO2 coated disks were tested in fully formulated oil and mineral oil provided by John Deere. Tribological performance was evaluated in both sliding and rolling condition. Corrosion resistance property were measured in 3.5% NaCl. Sliding performance were tested using High Frequency Reciproc (open full item for complete abstract)

Committee: Gary L. Doll (Advisor); Gregory N. Morscher (Committee Member); K.T. Tan (Committee Member); Rajeev K. Gupta (Committee Member); Robert Mallik (Committee Member) Subjects: Chemistry; Materials Science; Mechanical Engineering

Doctor of Philosophy, University of Akron, 2021, Mechanical Engineering

Planar inductive sensors have been widely used in non-contact displacement measurement applications. Due to their advantages such as low cost, easy installation, high accuracy, and stability in harsh environments, planar inductive sensors are typically used to measure turbine blade tip clearance, the displacement of metal parts in belts, and the movement of robots/manipulators. However, the planar inductive sensors has a lot of limitations. First, when the material, size, or shape of the target is changed, the calibration curve needs to be rebuilt since the eddy current varies in different materials. Second, the inductive sensor which has a high sensitivity always needs a high frequency excitation signal. This means that when using the inductive sensor in industrial applications, several high performance support instruments need to be used with the sensor, such as high sampling rate data acquisition system and multi-channel power source. All these limitations cause a lot of inconvenience while using the planar inductive sensor. To overcome the above problems, we first presented a new method for planar inductive sensors to measure the gap between the sensor and a non-ferrite metallic target. The eddy current on the target plate was modeled as a virtual coil. The mutual inductance between the sensing coils and the virtual coil was calculated. From our analysis, we found that when the target material is changed, the new calibration curve can be obtained by adding a constant to the base calibration curve. To verify the validity of the method, three planar inductive sensors with different dimensions were manufactured and used to measure the gap from four different non-ferrite targets (Cu, Al, Zn, and Ti). Results showed that the new calibration method has a small error of 3.2% in the 500 – 5000 μm measurement range. Second, in order to extend the new calibration method to any shape/size of the target, we presented an improved method to measure the gap from an irre (open full item for complete abstract)

Committee: Jiang Zhe Ph.D. (Advisor); Jae-Won Choi Ph.D. (Committee Member); Shengyong Wang Ph.D. (Committee Member); Hongbo Cong Ph.D. (Committee Member); Yi Pang Ph.D. (Committee Member) Subjects: Mechanical Engineering