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Influence Of Linear Reciprocating And Multi-Directional Sliding On Peek Wear Performance And Transfer Film Formation, Kevin A. Laux, Christian J. Schwartz 2019 Texas A&M University

Influence Of Linear Reciprocating And Multi-Directional Sliding On Peek Wear Performance And Transfer Film Formation, Kevin A. Laux, Christian J. Schwartz

Christian Schwartz

Because of their light weight, chemical resistance, and self-lubricating properties, polymers are used in applications ranging from biomedical to aerospace. Some polymers exhibit significant differences in wear resistancebased on whether they are in unidirectional or multidirectional sliding. Shear induced polymer chain orientation is believed to be responsible for this behavior. Polyetheretherketone (PEEK) has excellent wear resistance, but its multidirectional sliding behavior has not been thoroughly investigated. A factorial multidirectional pin-on-plate wear study of PEEK was conducted with a focus on molecular weight and sliding path directionality. These factors were studied for their correlation to over all wear performance. Additionally ...


Surface Layer Plastic Deformation As A Mechanism For Uhmwpe Wear, And Its Role In Debris Size., Kevin G. Plumlee, Christian J. Schwartz 2019 Oklahoma Christian University

Surface Layer Plastic Deformation As A Mechanism For Uhmwpe Wear, And Its Role In Debris Size., Kevin G. Plumlee, Christian J. Schwartz

Christian Schwartz

Ultra-high molecular weight polyethylene (UHMWPE) remains the primary bearing material for use in artificial joints, but the longevity of these implants is still hindered by an osteolytic immune system response initiated by sub-micron sized wear debris released from the UHMWPE bulk component. Studies have shown that the severity of the immune system response is linked to particle size. Current treatments for reducing this effect focus on reducing the total volume of wear, but do not directly address particle size due to a limited understanding of the mechanisms involved in producing such small debris. Directly observing these mechanisms is inherently challenging ...


Effects Of Contact Pressure, Molecular Weight, And Supplier On The Wear Behavior And Transfer Film Of Polyetheretherketone (Peek), Kevin A. Laux, Christian J. Schwartz 2019 Texas A&M University

Effects Of Contact Pressure, Molecular Weight, And Supplier On The Wear Behavior And Transfer Film Of Polyetheretherketone (Peek), Kevin A. Laux, Christian J. Schwartz

Christian Schwartz

Polyetheretherketone (PEEK) is a designation given to materials of the polyaryletherketone family having a characteristic distribution of ether and ketone groups in the polymer backbone. PEEK materials have high strength and chemical resistance as well as very high melting points and glass transition temperatures. Because of this combination of properties, PEEK materials find use for wear application in extreme environments where they provide a light-weight and corrosion resistant bearing material that often does not require lubrication. This study focused on determining the effects of supplier and molecular weight on the wear of particular PEEK materials, in addition to the effect ...


Skin Tribology Phenomena Associated With Reading Braille Print: The Influence Of Cell Patterns And Skin Behavior On Coefficient Of Friction, Matthew A. Darden, Christian J. Schwartz 2019 Iowa State University

Skin Tribology Phenomena Associated With Reading Braille Print: The Influence Of Cell Patterns And Skin Behavior On Coefficient Of Friction, Matthew A. Darden, Christian J. Schwartz

Christian Schwartz

Efficient transmission of tactile information is vital for individuals who rely on their sense of touch to interact with and navigate their surroundings, including visually impaired persons. Somatosensory phenomena have been investigated with respect to surface topologies and neuron sensitivities in the skin, but there is little knowledge of the specific skin tribology when reading tactual-coded information such as braille. Braille is a tactual code that employs raised dome-shaped dots in six-position cells (2 columns by 3 rows per cell), with various dot patterns representing individual text characters, punctuation or mathematical operators. Due to the hypothesized significance of friction on ...


Parametric Investigation Of Soft-Body Penetration Into Parallel-Ridged Textured Surfaces For Tactile Applications, Thomas J. Wilde, Christian J. Schwartz 2019 Iowa State University

Parametric Investigation Of Soft-Body Penetration Into Parallel-Ridged Textured Surfaces For Tactile Applications, Thomas J. Wilde, Christian J. Schwartz

Christian Schwartz

The tribological interactions between skin and textured surfaces has profound impact on both the tactile perception of the product being used, as well as the functionality of the product with regards to friction coefficient. Previous work has shown that parallel-ridged textures have vastly different friction coefficients with regards to the direction of skin sliding, and that penetration of the skin into the voids between ridges not only add contact area but also potential for interlocking. The ability to model skin penetration into textural elements would prove to be very useful for predicting friction; however, the mechanics of the problem are ...


Investigation Of Friction Mechanisms In Finger Pad Sliding Against Surfaces Of Varying Roughness, Geetha Chimata, Christian J. Schwartz 2019 Iowa State University

Investigation Of Friction Mechanisms In Finger Pad Sliding Against Surfaces Of Varying Roughness, Geetha Chimata, Christian J. Schwartz

Christian Schwartz

Human finger pad friction and the effects of surface features on the fingerprint ridges, shape of the finger and the material properties of the finger were investigated. The friction coefficients for three fine-grit abrasive papers were measured to assess these effects. Four probing surfaces were used: human index finger pad, silicone replicas of the finger with and without fingerprints, and a smooth silicone sphere. Friction tests were performed at a constant normal load of 0.5 N in two probe orientations: normal and perpendicular to the orientation of the fingerprint ridges. Scanning electron microscopy of the abrasive papers was performed ...


Investigation Of The Effect Of The Normal Load On The Incidence Of Friction Blisters In A Skin-Simulant Model, Geetha Chimata, Christian J. Schwartz 2019 Iowa State University

Investigation Of The Effect Of The Normal Load On The Incidence Of Friction Blisters In A Skin-Simulant Model, Geetha Chimata, Christian J. Schwartz

Christian Schwartz

A laminar skin simulant was constructed to study the incidence of friction blisters. The skin simulant consists of a thin polyurethane top layer and textured gum foam rubber bottom layer adhered to an acrylic-backing plate to emulate the layered structure of the human skin. Friction blisters were produced on the skin simulant by using a dual-axis tribometer. The effect of the applied normal load on the number of cycles required to produce a blister was investigated. The skin simulant was also analyzed as an adhesive-bonded laminar composite to determine the relationship between the applied normal load and the number of ...


Modeling Residual Stress Development In Hybrid Processing By Additive Manufacturing And Laser Shock Peening, Guru Charan Reddy Madireddy 2018 University of Nebraska - Lincoln

Modeling Residual Stress Development In Hybrid Processing By Additive Manufacturing And Laser Shock Peening, Guru Charan Reddy Madireddy

Mechanical (and Materials) Engineering -- Dissertations, Theses, and Student Research

The term “hybrid” has been widely applied to many areas of manufacturing. Naturally, that term has found a home in additive manufacturing as well. Hybrid additive manufacturing or hybrid-AM has been used to describe multi-material printing, combined machines (e.g., deposition printing and milling machine center), and combined processes (e.g., printing and interlayer laser re-melting). The capabilities afforded by hybrid-AM are rewriting the design rules for materials and adding a new dimension in the design for additive manufacturing paradigm. This work focuses on hybrid-AM processes, which are defined as the use of additive manufacturing (AM) with one or more ...


Powder Bed Surface Quality And Particle Size Distribution For Metal Additive Manufacturing And Comparison With Discrete Element Model, Irene Yee 2018 California Polytechnic State University, San Luis Obispo

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

Master's Theses and Project Reports

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 ...


Erosion Degradation Characteristics Of A Linear Electro-Hydrostatic Actuator Under A High-Frequency Turbulent Flow Field, Yuan Li, Shaoping Wang, Mileta M. Tomovic, Chao Zhang 2018 Old Dominion University

Erosion Degradation Characteristics Of A Linear Electro-Hydrostatic Actuator Under A High-Frequency Turbulent Flow Field, Yuan Li, Shaoping Wang, Mileta M. Tomovic, Chao Zhang

Engineering Technology Faculty Publications

The paper proposes a performance degradation analysis model based on dynamic erosion wear for a novel Linear Electro-Hydrostatic Actuator (LEHA). Rather than the traditional statistical methods based on degradation data, the method proposed in this paper firstly analyzes the dominant progressive failure mode of the LEHA based on the working principle and working conditions of the LEHA. The Computational Fluid Dynamics (CFD) method, combining the turbulent theory and the micro erosion principle, is used to establish an erosion model of the rectification mechanism. The erosion rates for different port openings, under a time-varying flow field, are obtained. The piecewise linearization ...


Mechanical Wear Debris Feature, Detection, And Diagnosis: A Review, Wei Hong, Wenjian Cai, Shaoping Wang, Mileta M. Tomovic 2018 Old Dominion University

Mechanical Wear Debris Feature, Detection, And Diagnosis: A Review, Wei Hong, Wenjian Cai, Shaoping Wang, Mileta M. Tomovic

Engineering Technology Faculty Publications

Mechanical debris is an important product of friction wear, which is also a crucial approach to know the running status of a machine. Many studies have been conducted on mechanical debris in related fields such as tribology, instrument, and diagnosis. This paper presents a comprehensive review of these studies, which summarizes wear mechanisms (e.g., abrasive wear, fatigue wear, and adhesive wear) and debris features (e.g., concentration (number), size, morphology, and composition), analyzes detection methods principles (e.g., offline: spectrograph and ferrograph, and online: optical method, inductive method, resistive-capacitive method, and acoustic method), reviews developments of online inductive methods ...


Characterization Of A Novel Variable Friction Connection For Semi-Active Cladding System, Yongqiang Gong, Liang Cao, Simon Laflamme, Spencer Quiel, James Ricles, Douglas Taylor 2018 Iowa State University

Characterization Of A Novel Variable Friction Connection For Semi-Active Cladding System, Yongqiang Gong, Liang Cao, Simon Laflamme, Spencer Quiel, James Ricles, Douglas Taylor

Civil, Construction and Environmental Engineering Publications

Cladding systems are conventionally designed to serve architectural purposes and protect occupants from the environment. Some research has been conducted in altering the cladding system in order to provide additional protection against natural and man-made hazards. The vast majority of these solutions are passive energy dissipators, applicable to the mitigation of single types of hazards. In this paper, we propose a novel semiactive variable friction device that could act as a connector linking a cladding panel to the structural system. Because of its semi-active capabilities, the device, here termed variable friction cladding connection (VFCC), could be utilized to mitigate different ...


Application Of Surface Treatments To Improve Fuel Efficiency Of Internal Combustion Engines, Amirabbas Akbarzadeh 2017 Louisiana State University and Agricultural and Mechanical College

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 ...


Silicon Carbide Materials Properties Selection For Mechanical Seal Faces, William Charles Hoskins 2017 University of Tennessee, Knoxville

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

University of Tennessee Honors Thesis Projects

No abstract provided.


Modeling And Computation Of The Maximum Braking Energy Speed For Transport Category Airplanes, Nihad E. Daidzic 2017 AAR Aerospace Consulting, LLC

Modeling And Computation Of The Maximum Braking Energy Speed For Transport Category Airplanes, Nihad E. Daidzic

Journal of Aviation Technology and Engineering

Transport-category or FAR/CS 25 certified airplanes may occasionally become braking energy capacity limited. Such limitation may exist when heavy airplanes are departing airports at high-density altitudes, on relatively long runways, and/or possibly with some tailwind component. A maximum braking energy VMBE speed exists which may limit the maximum allowable takeoff decision/action speed V1. The ever-existing possibility of high-speed rejected takeoff in such conditions may also limit the airplane gross weight for declared available distances. To gain deeper insights and acquire better understanding of the topic, a theoretical model of the maximum braking energy and the related VMBE ...


Investigation Of An Axial Flow Rotary Valve Seal, Joseph K. Stieha 2017 University of Kentucky

Investigation Of An Axial Flow Rotary Valve Seal, Joseph K. Stieha

Theses and Dissertations--Mechanical Engineering

This thesis investigates potential materials to be used in the rotary sealing industry that provide low power loss and minimize cost. The studied rotary valve utilizes slots that act as timing valves to allow for flow axially, through the seal face, at particular times within a heat pump cycle. This investigation examines various combinations of multiple PTFE materials, plastics, and soft metals that have been proven to provide low friction coefficients. Leakage and wear requirements are stated for the future use of the rotary valve and are used to determine the effectiveness of sealing the fluid while examining the power ...


Parametric Investigation Of Soft-Body Penetration Into Parallel-Ridged Textured Surfaces For Tactile Applications, Thomas J. Wilde, Christian J. Schwartz 2016 Iowa State University

Parametric Investigation Of Soft-Body Penetration Into Parallel-Ridged Textured Surfaces For Tactile Applications, Thomas J. Wilde, Christian J. Schwartz

Mechanical Engineering Publications

The tribological interactions between skin and textured surfaces has profound impact on both the tactile perception of the product being used, as well as the functionality of the product with regards to friction coefficient. Previous work has shown that parallel-ridged textures have vastly different friction coefficients with regards to the direction of skin sliding, and that penetration of the skin into the voids between ridges not only add contact area but also potential for interlocking. The ability to model skin penetration into textural elements would prove to be very useful for predicting friction; however, the mechanics of the problem are ...


Tribological Testing And Analysis Of Ionic Liquids As Candidate Anti-Wear Additives For Next-Generation Engine Lubricants, William Charles Barnhill 2016 University of Tennessee - Knoxville

Tribological Testing And Analysis Of Ionic Liquids As Candidate Anti-Wear Additives For Next-Generation Engine Lubricants, William Charles Barnhill

Masters Theses

In this work, fourteen ionic liquids (ILs) were assayed as potential next-generation engine oil additives. After screening for corrosion, thermal stability and oil solubility, candidate additives were subjected to friction and wear tests in both boundary and mixed regime lubrication. While each IL demonstrated friction and wear reduction compared to base oil without any additives, oil miscible ILs tetraoctylphosphonium bis 2-ethylhexyl phosphate ([P8888][DEHP]) and trioctylammonium bis 2-ethylhexylphosphate ([N888H][DEHP]) were the best performers in bench tests with a XX% and XX% improvement in wear over the base oil respectively. Each of these ILs excellent solubility and superior performance was ...


Study Of Role Of Meniscus And Viscous Forces During Liquid-Mediated Contacts Separation, Prabin Dhital 2016 Minnesota State University Mankato

Study Of Role Of Meniscus And Viscous Forces During Liquid-Mediated Contacts Separation, Prabin Dhital

All Theses, Dissertations, and Other Capstone Projects

Menisci may form between two solid surfaces with the presence of an ultra-thin liquid film. When the separation operation is needed, meniscus and viscous forces contribute to an adhesion leading stiction, high friction, possibly high wear and potential failure of the contact systems, for instance microdevices, magnetic head disks and diesel fuel injectors. The situation may become more pronounced when the contacting surfaces are ultra-smooth and the normal load is small. Various design parameters, such as contact angle, initial separation height, surface tension and liquid viscosity, have been investigated during liquid-mediated contact separation. However, how the involved forces will change ...


Investigation Of Friction Mechanisms In Finger Pad Sliding Against Surfaces Of Varying Roughness, Geetha Chimata, Christian J. Schwartz 2015 Iowa State University

Investigation Of Friction Mechanisms In Finger Pad Sliding Against Surfaces Of Varying Roughness, Geetha Chimata, Christian J. Schwartz

Mechanical Engineering Publications

Human finger pad friction and the effects of surface features on the fingerprint ridges, shape of the finger and the material properties of the finger were investigated. The friction coefficients for three fine-grit abrasive papers were measured to assess these effects. Four probing surfaces were used: human index finger pad, silicone replicas of the finger with and without fingerprints, and a smooth silicone sphere. Friction tests were performed at a constant normal load of 0.5 N in two probe orientations: normal and perpendicular to the orientation of the fingerprint ridges. Scanning electron microscopy of the abrasive papers was performed ...


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