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Full-Text Articles in Mechanical Engineering

Study Of The Temporal Characteristics Of Friction And Contact Behavior Encountered During Braille Reading, Matthew A. Darden, Christian J. Schwartz Apr 2017

Study Of The Temporal Characteristics Of Friction And Contact Behavior Encountered During Braille Reading, Matthew A. Darden, Christian J. Schwartz

Mechanical Engineering Publications

Beyond the sense of sight, the sense of touch is one of the primary ways that individuals experience their surrounding environment. Fundamentally understanding the relationship of skin-surface tribology and its elicited tactile attributes could provide a breakthrough in improving the ability to efficiently transmit tactile information to those who rely on the sense of touch to interact with their surroundings, such as the blind and visually impaired (BVI) community. The tactile language of braille has been adopted by the BVI community, employing configurations of raised dome-shape dots to convey what is ordinarily presented in text and image form. The coefficient ...


Development Of Durable Superhydrophobic Materials For Ice- And Snow-Free Airport Concrete Pavements, Therin Jamal Young Jan 2016

Development Of Durable Superhydrophobic Materials For Ice- And Snow-Free Airport Concrete Pavements, Therin Jamal Young

Graduate Theses and Dissertations

Superhydrophobic surfaces that mimic surfaces found in nature, such as the lotus leaf, are an attractive research topic in various fields of study because of their numerous applications. More recent studies have focused on superhydrophobic surfaces that reduce or completely stop the accretion of ice and snow on power lines and aircraft that operate in cold regions. The superhydrophobic phenomena is usually achieved by creating a dual-scale roughness that is composed of micro- and nano-scale structures that trap air in-between themselves and reduce the surface energy of the textured surface. The objective of this study was to assess the tribological ...


An Investigation Of Skin Tribology Phenomena Involved In Tactile Communication Through Braille And Its Associated Psychophysical Response During Task-Based Discrimination, Matthew Aguirre Darden Jan 2016

An Investigation Of Skin Tribology Phenomena Involved In Tactile Communication Through Braille And Its Associated Psychophysical Response During Task-Based Discrimination, Matthew Aguirre Darden

Graduate Theses and Dissertations

Most individuals utilize all five senses, especially their sense of sight, to create a unique sensory experience depicting the surrounding environment. Unfortunately, individuals in the blind and visually impaired (BVI) community lack the sense of sight and rely primarily on tactile means to acquire valuable or potentially vital information, leading to the advent of tactile communication methods like braille. A key challenge in controlling the haptic experience of a surface is the lack of fundamental understanding of how various surface attributes, such as friction and texture, affect the tactile response. Oftentimes, braille users experience tactile confusion when scanning complex tactual ...


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 May 2015

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

Mechanical Engineering Publications

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 ...


Plastic Flows And Phase Transformations In Materials Under Compression In Diamond Anvil Cell: Effect Of Contact Sliding, Biao Feng, Valery I. Levitas, Oleg M. Zarechnyy Jul 2013

Plastic Flows And Phase Transformations In Materials Under Compression In Diamond Anvil Cell: Effect Of Contact Sliding, Biao Feng, Valery I. Levitas, Oleg M. Zarechnyy

Aerospace Engineering Publications

Modeling of coupled plastic flows and strain-induced phase transformations (PTs) under high pressure in a diamond anvil cell is performed with the focus on the effect of the contact sliding between sample and anvils. Finite element software ABAQUS is utilized and a combination of Coulomb friction and plastic friction is considered. Results are obtained for PTs to weaker, equal-strength, and stronger high pressure phases, using different scaling parameters in a strain-controlled kinetic equation, and with various friction coefficients. Compared to the model with cohesion, artificial shear banding near the constant surface is eliminated. Sliding and the reduction in friction coefficient ...


Phase Field Approach To Interaction Of Phase Transformation And Dislocation Evolution, Valery I. Levitas, Mahdi Javanbakht Jun 2013

Phase Field Approach To Interaction Of Phase Transformation And Dislocation Evolution, Valery I. Levitas, Mahdi Javanbakht

Aerospace Engineering Publications

Phase field approach to coupled evolution of martensitic phase transformations (PTs) anddislocation is developed. A fully geometrically nonlinear formulation is utilized. The finite element method procedure is developed and applied to study the hysteretic behavior and propagation of an austenite (A)–martensite (M) interface with incoherency dislocations, the growth and arrest of martensitic plate for temperature-induced PT, and the evolution of phase and dislocation structures for stress-induced PT. A similar approach can be developed for the interaction of dislocations with twins and diffusive PTs described by Cahn-Hilliard theory.


Coupled Phase Transformations And Plastic Flows Under Torsion At High Pressure In Rotational Diamond Anvil Cell: Effect Of Contact Sliding, Biao Feng, Valery I. Levitas Jan 2013

Coupled Phase Transformations And Plastic Flows Under Torsion At High Pressure In Rotational Diamond Anvil Cell: Effect Of Contact Sliding, Biao Feng, Valery I. Levitas

Aerospace Engineering Publications

A three-dimensional large-sliding contact model coupled with strain-induced phase transformations (PTs) and plastic flow in a disk-like sample under torsion at high pressure in rotational diamond anvil cell (RDAC) is formulated and studied. Coulomb and plastic friction are combined and take into account variable parameters due to PT. Results are obtained for weaker, equal-strength, and stronger high pressure phases, and for three values of the kinetic coefficient in a strain-controlled kinetic equation and friction coefficient. All drawbacks typical of problem with cohesion are overcome, including eliminating mesh-dependent shear band and artificial plastic zones. Contact sliding intensifies radial plastic flow, which ...


Effect Of Conformational Change On Nanoscale Friction Behavior Of Organic Thin Films, Kanaga Karuppiah Kanaga Subramanian Jan 2008

Effect Of Conformational Change On Nanoscale Friction Behavior Of Organic Thin Films, Kanaga Karuppiah Kanaga Subramanian

Graduate Theses and Dissertations

The overarching theme of this dissertation is to probe relationships between structure of organic thin films and their specific functional property of friction in the context of various engineering applications. Two specific thin film systems were studied - biological macromolecules in total joint replacements and self-assembled alkanethiol monolayers for microdevice applications. Before delving into the actual systems, a thorough understanding of friction at small length scales was required. To address this, a friction study of two material pairs (Si3N4/mica and Si3N4/ultra-high molecular weight polyethylene) was conducted using a microtribometer and atomic force microscope (AFM) at the micro- and nanometer ...


Investigation Of Tribological Properties Of Biobased Polymers And Polymeric Composites, Satyam Kumar Bhuyan Jan 2008

Investigation Of Tribological Properties Of Biobased Polymers And Polymeric Composites, Satyam Kumar Bhuyan

Graduate Theses and Dissertations

Worldwide potential demands for replacing petroleum derived raw materials with renewable plant-based ones in the production of valuable polymeric materials and composites are quite significant from the social and environmental standpoints. Therefore, using low-cost renewable resources has deeply drawn the attention of many researchers. Among them, natural oils are expected to be ideal alternative feedstock since oils, derived from plant and animal sources, are found in profusion in the world. The important feature of these types of materials is that they can be designed and tailored to meet different requirements. The real challenge lies in finding applications which would use ...


Surface Friction Guiding For Reduced High-Frequency Lateral Vibration Of Moving Media, V. Kartik, Jonathan A. Wickert Jun 2007

Surface Friction Guiding For Reduced High-Frequency Lateral Vibration Of Moving Media, V. Kartik, Jonathan A. Wickert

Jonathan A. Wickert

The free and forced vibration of a moving medium is examined in an application where distributed friction guiding is used to control lateral position passively. Subambient pressure features formed in the guides intentionally modify the naturally occurring self-pressurized air bearing and increase the contact force between the medium and the guide's surface. These features increase friction to a level beyond that achievable based on the nominal wrap pressure. The moving medium is modeled as a beam that is transported over frictional regions and subjected to prescribed boundary disturbances arising from runout of a supply or take-up roll. For axial ...


The Effect Of Autocorrelation Length On The Real Area Of Contact And Friction Behavior Of Rough Surfaces, Yilei Zhang, Sriram Sundararajan Jan 2005

The Effect Of Autocorrelation Length On The Real Area Of Contact And Friction Behavior Of Rough Surfaces, Yilei Zhang, Sriram Sundararajan

Mechanical Engineering Publications

Autocorrelation length (ACL) is a surface roughness parameter that provides spatial information of surfacetopography that is not included in amplitude parameters such as root-mean-square roughness. This paper presents a relationship between ACL and the friction behavior of a rough surface. The influence of ACL on the peak distribution of a profile is studied based on Whitehouse and Archard’s classical analysis [Whitehouse and ArchardProc. R. Soc. London, Ser. A316, 97 (1970)] and their results are extended to compare profiles from different surfaces. The probability density function of peaks and the mean peak height of a profile are given as functions ...


Static Friction And Surface Roughness Studies Of Surface Micromachined Electrostatic Micromotors Using An Atomic Force/Friction Force Microscope, Sriram Sundararajan, Bharat Bhushan Jan 2001

Static Friction And Surface Roughness Studies Of Surface Micromachined Electrostatic Micromotors Using An Atomic Force/Friction Force Microscope, Sriram Sundararajan, Bharat Bhushan

Sriram Sundararajan

A technique to measure the static friction forces (stiction) encountered in surface micromachined micromotors using a commercial atomic force microscope (AFM)/friction force microscope has been developed and is described. An AFM tip is pushed against a rotor arm of the micromotor so as to generate lateral deflection (torsion) of the tip, which is measured by the AFM. The maximum value of the lateral deflection obtained prior to rotor movement (rotation) is a measure of the static friction force of the micromotors. This technique was employed to study the effect of humidity and rest time on the static friction force ...


Topography-Induced Contributions To Friction Forces Measured Using An Atomic Force/Friction Force Microscope, Sriram Sundararajan, Bharat Bhushan Jan 2000

Topography-Induced Contributions To Friction Forces Measured Using An Atomic Force/Friction Force Microscope, Sriram Sundararajan, Bharat Bhushan

Sriram Sundararajan

Most friction studies using an atomic force/friction force microscope, while concentrating on material-induced effects, often present users with conflicting and confusing interpretations of the topography-induced friction forces. It has been generally reported that topography-induced contributions are independent of scanning direction and can be removed by subtracting friction data from forward and backward scans. In this article, we present friction studies on samples with well-defined topography variations and find that the above-given statement is not generally true. At surface locations involving significant changes in topography, the topography-induced contributions to friction forces are found to be different between forward and backward ...


Rolling Coefficient Of Friction Of Rubber Tires , Merlin Lyle Millett Jr. Jan 1957

Rolling Coefficient Of Friction Of Rubber Tires , Merlin Lyle Millett Jr.

Retrospective Theses and Dissertations

This thesis presents a method for: (1) Correlating experimental load-deflection diagrams for aircraft tires. (2) Analytically determining the vertical tire deflection. (3) Developing an equation for the rolling coefficient of friction;Results obtained by this analysis were compared with measure deflections at aircraft tires in which as much as 50% deflection is allowed. These measured values were obtained from load-deflection tests conducted by Goodyear Tire and Rubber Company, the Firestone Tire and Rubber Company the B. F. Goodrich Company and the United States Rubber Company;Results obtained from this analysis were compared with measure values of the rolling coefficients of ...