Tribology Commons^™

Finite Element Analysis Of The Bearing Component Of Total Ankle Replacement Implants During The Stance Phase Of Gait, Timothy S. Jain

Master's Theses

Total ankle replacement (TAR) implants are an effective option to restore the range of motion of the ankle joint for arthritic patients. An effective tool for analyzing these implants’ mechanical performance and longevity in-silico is finite element analysis (FEA). ABAQUS FEA was used to statically analyze the von Mises stress and contact pressure on the articulating surface of the bearing component in two newly installed fixed-bearing total ankle replacement implants (the Wright Medical INBONE II and the Exactech Vantage). This bearing component rotates on the talar component to induce primary ankle joint motion of plantarflexion and dorsiflexion. The stress response …

Improving Hexapod Platform Pose Accuracy - A Photogrammetry-Based Approach, Sourabh Karmakar

All Dissertations

The aim of this research is to make a newly constructed Stewart-Gough Platform-based test frame Tiger 66.1 operational by developing control software and estimating the error in its pose accuracy. The accuracy of the platform is affected by one source or multiple sources. The typical error sources are kinematic and structural, some of them originate from manufacturing imperfections, assembly deviations, elastic deformations, thermal deformations, and joint clearances which change the expected kinematic behavior of the manipulator. Also, some non-mechanical errors like transmission error, sensor accuracy, algorithm error, and truncation error in calculation contribute significantly in some cases. Using pose deviations …

Molecular Dynamics Study Of Characterization In Metal-Free Friction Materials, Yizhan Zhang

Electronic Theses and Dissertations

Metallic friction materials currently used in industry may adversely impact the environment. Substitutions for metals in friction materials, on the other hand, can introduce operational safety issues and other unforeseeable issues such as thermal-mechanical instabilities and insufficient strength. In view of it, this dissertation focuses on developing different kinds of materials from simple structure to complex structure and evaluating the material properties with the assistance of molecular dynamics (MD) tools at the nano scale.

First, the concept of the contacted surfaces in friction at the atomic scale was introduced in order to get accurate understanding of the friction process compared …

Improving Tribological Properties Of Polydopamine/Polytetrafluoroethylene Coatings Through Incorporating Core-Shell Nanoparticles And Laser Surface Texturing, Firuze Soltani-Kordshuli

Graduate Theses and Dissertations

Polytetrafluoroethylene (PTFE) is a widely used polymer that has unique properties such as chemical and temperature resistance, corrosion resistance, low maintenance cost, and a very low coefficient of friction (COF). These distinctive properties have made PTFE a promising candidate for industrial applications where surfaces are in relative motion. PTFE can be utilized as a thin film solid lubricant to significantly reduce the friction between moving surfaces. However, PTFE coatings have low cohesion and poor adhesion to the substrate resulting in its low wear resistance. This fact limits the application of PTFE coatings in load-bearing situations. To address these limitations, an …

Timken Black Oxide False Brinelling Project, Elizabeth Kotzalas

Williams Honors College, Honors Research Projects

There is a known issue that occurs in wind turbine main shaft bearings, among other bearing types and applications during transportation or while the turbine is powered on, but the bearing is not spinning. This issue is damage that is confined to mostly the raceways but can damage the rollers over time. It is called false brinelling and is a material removal from the raceways due to repeated tiny vibrations of the rollers over the same area. A question was posed on whether black oxide surface treatment could reduce false brinelling wear on bearings in this application, and as a …

An Investigation Into The Velocity-Dependence Of The Coefficient Of Friction Between Concrete And Maraging Steel, Trace A. Duncan

Theses and Dissertations

This work investigates the velocity-dependent coefficient of friction between concrete and 300 Maraging steel over short displacements. A modified torsional Hopkinson bar is utilized for rotating thin-walled steel rings in contact with a concrete disk under static precompression. Rotational velocity is varied between tests to determine the velocity dependence of the friction coefficient. Normal force is varied between certain tests to determine the pressure dependence of the friction coefficient between the concrete and steel. Three different types of concrete are tested to deduce any composition effect on the friction coefficient. Dry and greased conditions’ impact on the friction coefficient are …

Motion And Crosslinked Polyethylene Wear In Reverse Total Shoulder Arthroplasty, Christopher Millward

Electronic Thesis and Dissertation Repository

The reverse total shoulder arthroplasty (RTSA) has quickly grown to become the most commonly used shoulder arthroplasty design; however, reports have shown evidence of RTSA failures related to polyethylene wear and damage. Therefore, the present work investigated the wear of crosslinked polyethylene (XLPE) in environments similar to that of an in vivo RTSA. Additionally, a computational model was developed based on a previous study of the shoulder motions obtained from a selection of typical patients with RTSA. This model quantified the amount of glenohumeral motion that an RTSA may be subjected to in vivo and provided an approximate value for …

Experimental And Theoretical Investigation Of Vibro-Impact Triboelectric Energy Harvesters, Mostafa Hassan

Mechanical Engineering Theses

Improving the efficiency of energy harvesting, by investigating different techniques to increase the harvester bandwidth, as well as by exploring the influencing factors and adjusting them to optimal setups. Towards this, multiple Vibro-impact energy harvesters were proposed in this study. First, a Two-Degree of Freedom (2DOF) Vibro-impact Triboelectric Energy Harvester with a single and a double impact configuration is proposed. Multi-modality and piecewise linearity were combined to improve the harvesting bandwidth of triboelectric energy harvesters utilizing two resonant frequencies. The harvester structure consists of a primary cantilever beam attached to a secondary cantilever beam through a tip mass in the …

Tribological Studies Of Thick Polytetrafluoroethylene Coatings Enhanced By Polydopamine And Nanoparticles, Sujan Kumar Ghosh

Graduate Theses and Dissertations

Polytetrafluoroethylene (PTFE) is a popular low friction solid lubricant with high chemical and thermal stability. Thick PTFE coatings have the potential for many tribological applications, such as replacing Tin-based Babbitt materials in journal bearings. However, the weak bonding strength to the substrate and the high wear rate of PTFE coatings are current limiting factors. The lack of understanding of their tribological properties and wear mechanisms in oil-lubricated conditions and how coating thickness affects the tribological performance further hindered the use of PTFE coatings. In this dissertation, polydopamine (PDA), a bio-inspired adhesive, is used as an underlayer for or as a …

High Temperature Degradation In Gan-Based Hall Effect Sensors, Alexis Anne Krone

Graduate Theses and Dissertations

This research focuses on understanding the effects of accelerated aging through temperature and environment on novel gallium nitride-based Hall effect magnetic field sensors and determining device reliability under electric vehicle operating conditions. The device reliability was modeled using accelerated aging for the temperatures of 200 °C, 350 °C, 450 °C, and 600 °C under various time steps unique to each temperature and either air, which is identical to operating circumstances, or argon, which would model the hermetic packaging environment. Using a high temperature furnace and oven, devices underwent high temperature storage tests at a chosen temperature and time step. Afterwards, …

An Investigation Of Testing Parameters On The Frictional Properties Of Patterned Core-Shell Nanostructures, Colin Phelan

Graduate Theses and Dissertations

Friction tests are a beneficial means to analyze the tribological characteristics and advantages of materials and textured surfaces. However, the selected test parameters can significantly influence the results. This work explores the significance of the friction testing parameters on the frictional performances of core-shell nanostructure-textured surfaces (CSNTSs). Several applied normal loads (10 μN, 100 μN, and 500 μN) and diamond counterface indenter tip radii (1 μm, 5 μm, and 20 μm) were selected for the testing of Al/diamond-like-carbon (DLC) and Al/amorphous silicon (a-Si) CSNTSs. The measured friction values of the CSNTSs were then compared to a matching Al/DLC film and …

Solid State Synthesis And Characterization Of Apatite Based Ceramic Waste Form For The Immobilization Of Radioactive Iodine, Md Imdadul Islam

LSU Doctoral Dissertations

The growing demand for nuclear power in the United States and worldwide is accountable for addressing the major concern of radioactive waste, involving the technical challenges of maintaining the nuclear fuel cycle and immobilizing high-level wastes for safe disposal in geological storage. The appropriate selection of waste forms for spent nuclear fuel such as fission products and radionuclides can be effective means for a feasible and sustainable nuclear fuel cycle. But highly volatile radionuclides such as iodine (129) are of specific concern due to its extraordinary long half-life (15.7 million years). Due to its poor solubility and high volatility at …

Design Of High Stability Superhydrophobic Surfaces, Shuo Wang

Major Papers

In the recent two decades, superhydrophobic surfaces' properties and their potential applications have attracted much attention. With the main advantages of self-cleaning, anti-icing, and drag-reduction, the superhydrophobic surfaces can be applied to many industry fields. But the traditional fabrication methods developed in the last twenty years for the superhydrophobic surfaces were focusing on mimicking nature. Specifically, most of the fabrication methods were based on the micro, and nano-scale structure of plants and animals, which came with the problems that such weeny structure on the surfaces would be damaged easily in the practical application without the self-healing capability like the creatures …

Pulse Reverse Current Electrodeposited Tio2 Doped Ni-W Coating, Sydney Hughes

Williams Honors College, Honors Research Projects

Nickel-Tungsten (Ni-W) coatings via the pulse reverse current method have been under development as a potential replacement for typical Chromium/Cadmium coatings. To increase the effectiveness of Ni-W as a coating, dopants have been tested to decrease microcracks and pores and increase overall tribological performance. Previous research by Timken Engineered Surfaces Laboratory showed that Ni-W doped with TiO₂ nanoparticles had a positive effect on coating performance. The purpose of this study was to determine the ideal solution parameters (i.e. TiO₂ concentration, pH) to maximize the benefit of the dopant when samples are subjected to tribological testing. Here, solutions of …

Thermomechanical Mechanisms That Cause Adhesion Of Aluminum High Pressure Die Castings To The Die, Alex Monroe

Dissertations, Master's Theses and Master's Reports

In high pressure die casting (HPDC) of aluminum, cast material adhering to die is a significant defect. Adhesion occurs in two primary ways. The casting may stick preventing its removal from the die. Aluminum can also adhere to the die and buildup in local areas on the die surface with additional casting cycles. This second form of adhesion is called soldering. Lubricant is the best technology to control all forms of adhesion, but it comes at the cost of casting porosity, blisters, reduced die life, and increased die casting machine wear. New strategies to prevent adhesion are desired to eliminate …

Viscoelasticity Of Ptfe-Based Face Seals, Bo Tan

Theses and Dissertations--Mechanical Engineering

PTFE-based materials are widely used in areas of tribology, particularly in seal and bearing applications because of their outstanding self-lubricating properties. Often in dynamic seal applications there is a need for ultra-low mechanical friction loss between the sealing surfaces. Due to its extremely low friction coefficient, there is interest in employing Polytetrafluoroethylene (PTFE) materials in such applications. One challenging aspect of employing PTFE is that these materials are viscoelastic and plastic. This dissertation concentrates on the modeling of viscoelastic material response when used as mechanical face seals with a focus on PTFE-based materials. First, the viscoelastic characteristics are measured through …

A Semi-Active Vibration Isolator For 3d Printing On Shipboard, Mohammad Z. Shahabuddin

Electronic Theses and Dissertations

In the recent years, additive manufacturing (AM) (aka 3D printing)-has become a viable alternative to traditional manufacturing due to its unique advantages, such as enabling the fabrication of complex geometries at reduced weight and costs as well as allowing on-site fabrication for maintenance and repair. One specific application area of the AM is the navy vessels. During extended voyages, the navy vessels likely require the convenience of on-site fabrication of the malfunctioned parts. However, the shipboard equipment suffers from a broad range of external excitations arising not only from the waves but also from the vessel’s engines, which …

Mechanical And Frictional Behavior Of Textured And Non-Textured Surfaces, Raghuram R. Santhapuram

Graduate Theses and Dissertations

Tribology is the study of surfaces where two objects are sliding against another. Significant energy is lost due to friction between the sliding surfaces. Therefore, developing or designing surfaces to minimize friction is critical for the durability and reliability of the mechanical components. Several researchers have identified that surface texturing at the nanoscale (nanotexture) would reduce the friction between the contacting surfaces. The nanotextured surfaces have several applications in microelectromechanical systems and nanoelectromechanical systems. This dissertation employs molecular dynamics simulations to investigate the frictional and mechanical response of nanotextured aluminum (Al) and Al/amorphous silicon (a-Si) composite surfaces.

This study determines …

Correlating The Physicochemical Properties Of Magnesium Stearate With Tablet Dissolution And Lubrication, Julie L. Calahan

Theses and Dissertations--Pharmacy

Magnesium stearate (MgSt) is the most commonly used pharmaceutical excipient and is present in over half the tablet formulations on the market. In spite of its popularity as an effective lubricant, it has been repeatedly recognized that there is significant variability between MgSt samples, which can cause inconsistent lubrication between batches of MgSt. The hypothesis of this research is that the batch-to-batch variability in tablet lubrication and dissolution observed in tablet formulations containing different MgSt samples can be correlated with differences in MgSt physicochemical properties (fatty acid salt composition, crystal hydrate form, particle size and surface area). Developing correlations between …

Experimental Studies Of Interfacial Behavior Of Contact System During Liquid Mediated Rough Surfaces Separation, Nhat Le

All Graduate Theses, Dissertations, and Other Capstone Projects

In the applications related to liquid-solid interface, their operation could be affected by the properties of the interface especially the applications that have infinitesimal interaction force at the interface surface and high interaction velocity. This study provides real time dynamic force measurement in separation process along with the real time image acquisition to explain the deviation between theoretical and experimental methods. The experimental design, setup and initial conditions for experiment are described in detail for further study related to liquid separating force. The simulation model is created to apply the theoretical model in prediction of meniscus force for different initial …

Final Design Review: Wear Test Machine, Justin Ju-Han Hou, Abraham Jack Mitchell, Alexandra Denae Pavano, Jahyun Kaylla Son

Mechanical Engineering

A California Polytechnic State University Senior Project team has been tasked by Marvin Engineering Co. to design and build a friction wear test fixture; the fixture is to characterize the coefficient of friction and potential friction wear of various industry adopted metal pairings in an oxygen-free environment. This final design review serves to document project research, full design process, method of operation of final product, and a comprehensive testing procedure.

The R&D department at Marvin Engineering Co. proposed this investigation in order to explore the phenomenon of friction and adhesive wear, specifically the occurrence of galling between stainless steel surfaces. …

Investigation Of Chip-Form And Tool-Wear In Turning Of Hardened Af9628 Alloy Under Various Cooling And Lubrication Conditions, Jason Wolf

Theses and Dissertations--Manufacturing Systems Engineering

Next generation defense and commercial applications for structural steels require new alloys that eliminate or reduce critical elements from their composition to lower cost and improve manufacturability, while maintaining or exceeding high strength and toughness requirements. A new alloy, denoted as AF9628, has recently been developed for this purpose and its manufacturing characteristics and the material response in component manufacturing must be fully understood.

In the present study, hardened AF9628 alloy was turned with a coated carbide cutting tool under fixed cutting speed, feed rate, and depth of cut parameters. This work focuses on chip-form and tool-wear analysis to understand, …

Photochemical Etching Of Nitrided Stainless Steel Piston Rings, Steven Sonntag

Mechanical Engineering Undergraduate Honors Theses

Piston rings are designed to provide a seal between the piston and the cylinder wall of internal combustion engines, keeping oil from the crankcase from getting into the combustion chamber. This means piston rings are the main point of contact between the piston and the cylinder wall, which causes the piston to experience high amounts of friction and wear. By texturing the surfaces of the cylinder wall and/or the piston ring, the amount of contact area can be reduced, allowing for less friction, slower wear, and better gas mileage. In this thesis experiments, photochemical etching processes were developed to etch …

Incorporation Of Silica Nanoparticles Into The Underlayer Of Pda/Ptfe Thin Coatings, Adedoyin Abe

Mechanical Engineering Undergraduate Honors Theses

Polytetrafluoroethylene (PTFE) is one of the most low friction and corrosion resistant solid lubricants. Prior studies have shown that a polydopamine (PDA) underlayer enhances the durability of PTFE thin coating. In this study, 100, 200, and 300 µL of aqueous silica nanoparticle (NP) solutions were added to the PDA deposition solution. The durability and coefficient of friction of PDA/PTFE thin coatings on stainless steel substrates are investigated with and without incorporating the silica NPs. The coatings were tested in dry contact conditions using a Universal Mechanical Tester (UMT) with a ball-on-flat configuration in a reciprocating motion. It was found that …

Understanding The Evolution Of Surface Texture Under Boundary Lubrication, Salil T. Bapat

Graduate Theses and Dissertations

The objective of this research was to understand the evolution of surface texture under boundary/mixed lubrication (BL). Significant material/energy losses occur during BL because of direct contact between the two surfaces. Traditionally, tribofilms have been studied extensively for BL while textures have been used as a static engineering design parameter to enhance lubricant film properties. However, texture is dynamic at the tribological mating interface, where both physical and chemical interactions are continuously modulated. The evolution and the interplay between the tribofilm and texture is least studied in the literature, which is the focus of this research.

MoS2-based lubricants, known for …

A Nanoindentation Study Of The Fatigue Properties Of Al/A-Si Core-Shell Nanostructures, Jason Steck

Mechanical Engineering Undergraduate Honors Theses

Nanostructure-textured surfaces can reduce friction and increase the reliability of micro- and nanoelectromechanical systems (NEMS/MEMS). For MEMS incorporating moving parts, the fatigue properties of nanostructures pose a challenge to their reliability in long-term applications. In this study, the fatigue behavior of hemispherical Al/a-Si core-shell nanostructures (CSNs), bare hemispherical Al nanodots, and a flat Al/a-Si layered thin film have been studied using nanoindentation and nano-scale dynamic mechanical analysis (nano-DMA) techniques. Fatigue testing with nano-DMA shows that the deformation resistance of CSNs persists through 5.0 × 10⁴ loading cycles at estimated contact pressures greater than 15 GPa. When the a-Si shell …

Evaluation Of High Velocity Wear, Armando Deleon

Theses and Dissertations

The HHSTT located at Holloman Air Force Base conducts hypersonic testing in a unique way. Rather than perform cost prohibitive flight testing or hypersonic wind tunnel testing, a rocket-powered sled propels test articles down a track. This test setup has been used to test at speeds up to 2885 m/s (~Mach 8.6). The sled is kept on the rails by utilizing slippers, fabricated to wrap around the rail [1]. This slipper design keeps the sled from separating from the rail during a test due to the airflow producing lift, in a designed effort to minimize the wear that occurs during …

Powder Bed Surface Quality And Particle Size Distribution For Metal Additive Manufacturing And Comparison With Discrete Element Model, Irene Yee

Master's Theses

Metal additive manufacturing (AM) can produce complex parts that were once considered impossible or too costly to fabricate using conventional machining techniques, making AM machines an exceptional tool for rapid prototyping, one-off parts, and labor-intensive geometries. Due to the growing popularity of this technology, especially in the defense and medical industries, more researchers are looking into the physics and mechanics behind the AM process. Many factors and parameters contribute to the overall quality of a part, one of them being the powder bed itself. So far, little investigation has been dedicated to the behavior of the powder in the powder …

Application Of Surface Treatments To Improve Fuel Efficiency Of Internal Combustion Engines, Amirabbas Akbarzadeh

LSU Master's Theses

To improve the tribological performance of contacting surfaces, different surface modification methods can be employed. Surface texturing and surface coating are examples of viable techniques developed for this purpose. Surface texturing involves creating micropatterns on the contacting surfaces while surface coating requires depositing a thin layer of a suitable material on the surface(s) to improve the component’s friction and wear characteristics. The performance of textured surfaces is affected by the geometric characteristic of textures.When dealing with surface coating parameters, the parameters of interests are the type of coating materials and their thicknesses.

The current study aims to experimentally study the …

Silicon Carbide Materials Properties Selection For Mechanical Seal Faces, William Charles Hoskins

Chancellor’s Honors Program Projects

No abstract provided.