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Effects Of Contact Pressure, Molecular Weight, And Supplier On The Wear Behavior And Transfer Film Of Polyetheretherketone (Peek), Kevin A. Laux, Christian J. Schwartz 2013 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

Mechanical Engineering Publications

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 ...


Enhanced Tribological Properties Of Surfaces Patterned With Su8/Dlc Microstructures, Luke Osborn 2013 University of Arkansas, Fayetteville

Enhanced Tribological Properties Of Surfaces Patterned With Su8/Dlc Microstructures, Luke Osborn

Inquiry: The University of Arkansas Undergraduate Research Journal

In tribology (the study of friction, wear, and lubrication), it is known that micro-textured surfaces can reduce friction due to decreased contact area between two surfaces. The problem with many micro-textures, however, is their inability to withstand significant amounts of wear, thus limiting their potential uses and overall effectiveness. In this study, connected and isolated microstructures of SU8, a negative tone photoresist, coated with and without diamond-like carbon (DLC), were designed to investigate the effects of these microstructures and DLC coating on the tribological performance of a surface. Friction and wear studies were conducted using a tribometer; surface topography and ...


Analytical Solutions Of Piston Ring Lubrication Using Mass Conserving Cavitation Algorithm, Jerzy Sawicki, Biao Yu 2012 Cleveland State University

Analytical Solutions Of Piston Ring Lubrication Using Mass Conserving Cavitation Algorithm, Jerzy Sawicki, Biao Yu

Jerzy T. Sawicki

A novel analytical approach for piston ring lubrication solution is presented by taking proper account of mass conservation in the cavitated region (JFO boundary conditions). A system of five nonlinear equations is employed to calculate such parameters as oil film thickness, frictional force, power loss, and oil flow rate. For an enclosed cavitation pattern in piston-ring assembly it was found, that JFO boundary conditions give much better accounting of the estimation of friction force, power loss and flow rate. To show the effectiveness of the undertaken approach, the widely accepted Jeng's approach (Jeng, 1992a) was selected, in which the ...


Static And Dynamic Analysis Of Bearings For Truck Brake Compressor, Biao Yu, Jerzy Sawicki, V. Dunaevsky 2012 Cleveland State University

Static And Dynamic Analysis Of Bearings For Truck Brake Compressor, Biao Yu, Jerzy Sawicki, V. Dunaevsky

Jerzy T. Sawicki

Mobility method is used to analyze the steady-state performance of crankshaft and connecting rod bearings which are subjected to loads whose magnitude and direction both vary in time. The steady-state characteristics include journal center orbit, minimum film thickness, maximum film pressure, effective temperature, flow through the bearing, etc. To extract the stiffness and damping coefficients over the load cycle, linear analysis method based on a short-bearing approximation is employed. In addition, the oil flow through the main and connecting rod bearings is investigated. Sufficient lubrication conditions for these bearings are discussed. This combined analysis is supported by numerical simulations.


Experimental And Theoretical Rotordynamic Characteristics Of A Hybrid Journal Bearing, Jerzy Sawicki, R. Capaldi, M. Adams 2012 Cleveland State University

Experimental And Theoretical Rotordynamic Characteristics Of A Hybrid Journal Bearing, Jerzy Sawicki, R. Capaldi, M. Adams

Jerzy T. Sawicki

This paper describes an experimental and theoretical investigation of a four-pocket,oil-fed, orifice-compensated hydrostatic bearing including the hybrid effects of journalrotation. The test apparatus incorporates a double-spool-shaft spindle which permitsindependent control over the journal spin speed and the frequencyof an adjustable-magnitude circular orbit, for both forward and backwardwhirling. This configuration yields data that enables determination of thefull linear anisotropic rotordynamic model. The dynamic force measurements weremade simultaneously with two independent systems, one with piezoelectric loadcells and the other with strain gage load cells. Theoreticalpredictions are made for the same configuration and operating conditionsas the test matrix using a finite-difference solver ...


Nonlinear Prediction Of Rotordynamic Coefficients For A Hydrodynamic Journal Bearing, Jerzy Sawicki, T.V.V.L. Rao 2012 Cleveland State University

Nonlinear Prediction Of Rotordynamic Coefficients For A Hydrodynamic Journal Bearing, Jerzy Sawicki, T.V.V.L. Rao

Jerzy T. Sawicki

In the analysis of hydrodynamic journal bearings, linearized stiffness and damping coefficients are widely used for the evaluation of stability and dynamic response characteristics. Under given operating conditions, these coefficients vary along the locus of the orbital response, and are not valid at large amplitudes (40% of the bearing clearance) of the journal motion. The time history of journal bearing motion for large vibrations is accurately predicted herein using nonlinear (time-transient) analysis. This paper discusses the adequacy of bearing analysis based on linearized coefficients and presents the significance of variation of the coefficients under the dynamic conditions. A method to ...


Analytical Solution Of Piston Ring Pack Lubrication For Truck Air Brake Compressor, Biao Yu, Jerzy Sawicki, V. Dunaevsky 2012 Cleveland State University

Analytical Solution Of Piston Ring Pack Lubrication For Truck Air Brake Compressor, Biao Yu, Jerzy Sawicki, V. Dunaevsky

Jerzy T. Sawicki

This paper presents an analytical solution of piston ring pack lubrication for two-cylinder truck air brake compressor. A system of nonlinear equations with seven variables was developed to describe lubrication phenomena of the piston ring pack for both fully flooded and starvation conditions. The full mass conservation boundary conditions defined by JFO ([ 14 ],[ 15 ]) theory were employed for complete description of the cavitation algorithm with enclosed and open cavitation patterns. Impact of the piston ring design parameters such as offset, crown height, and tension on the oil transport, lubrication conditions and friction losses of the compressor were discussed in details.


Stability Characteristics Of Herringbone Grooved Journal Bearings Incorporating Cavitation Effects, T.V.V.L. Rao, Jerzy Sawicki 2012 Birla Institute of Technology and Science

Stability Characteristics Of Herringbone Grooved Journal Bearings Incorporating Cavitation Effects, T.V.V.L. Rao, Jerzy Sawicki

Jerzy T. Sawicki

Stabilitycharacteristics of the herringbone grooved journal bearings (HGJBs) are analyzedtaking into account cavitation of the fluid flow. The perturbedvalues of pressure and film thickness from a given equilibriumposition are substituted into the Elrod's universal equation, which considersmass conservation in the complete bearing geometry. In order toanalyze the herringbone groove configuration, the governing equations under steadyand perturbed states are transformed to a rectangular domain usingthe grid transformation techniques. It is assumed that under perturbedconditions, the cavitation extent in the bearing remains unchanged andthe pressure gradients are computed in the full film region.The linearized stiffness and damping coefficients are evaluated ...


Linear Stability Analysis For A Hydrodynamic Journal Bearing Considering Cavitation Effects, T.V.V.L. Rao, Jerzy Sawicki 2012 Birla Institute of Technology and Science

Linear Stability Analysis For A Hydrodynamic Journal Bearing Considering Cavitation Effects, T.V.V.L. Rao, Jerzy Sawicki

Jerzy T. Sawicki

The purpose of this paper is to present the two-dimensional linear stability analysis considering the fluid flow in both full film and cavitation regions for a plain cylindrical journal bearing. The Lund's infinitesimal perturbation procedure is applied to Elrod's universal equation for evaluation of unsteady pressure gradients. Based on JFO theory, the pressure distribution, film rupture, and reformation boundaries can be obtained using Elrod's universal equation, for a given operating position of the journal. In this work, it is assumed that for infinitesimal perturbation of a journal about the equilibrium position, the film rupture and film reformation ...


Dynamic Coefficient Prediction In Multi-Lobe Journal Bearings Using A Mass Conservation Algorithm, T.V.V.L. Rao, Jerzy Sawicki 2012 Birla Institute of Technology and Science

Dynamic Coefficient Prediction In Multi-Lobe Journal Bearings Using A Mass Conservation Algorithm, T.V.V.L. Rao, Jerzy Sawicki

Jerzy T. Sawicki

A numerical procedure incorporating cavitation modeling in the predication of dynamic coefficients for four multi-lobe bearings is presented. A first order perturbation solution of the density (or fractional film content) is obtained by using the Elrod universal equation. The Elrod algorithm conserves mass throughout the bearing and automatically predicts the full film and cavitation regions using a switch function. In this work, the cavitation boundary predicted under steady state is considered for calculation of four unsteady pressure gradients. Results of stiffness and damping coefficients are presented for four multi-lobe bearing configurations, viz., two-axial groove, elliptical, three-lobe and offset cylindrical bearing ...


Magnetic Bearings For Non-Destructive Health Monitoring Of Rotating Machinery Supported In Conventional Bearings, M. Kasarda, D, Quinn, T. Bash, D. Inman, R. Kirk, Jerzy Sawicki 2012 Virginia Tech

Magnetic Bearings For Non-Destructive Health Monitoring Of Rotating Machinery Supported In Conventional Bearings, M. Kasarda, D, Quinn, T. Bash, D. Inman, R. Kirk, Jerzy Sawicki

Jerzy T. Sawicki

This paper describes initial results from a project expanding the field of rotor health monitoring by using Active Magnetic Bearings (AMBs) as actuators for applying a variety of known force inputs to a spinning rotor in order to monitor and evaluate response signals resulting from these inputs on-line. Similar to modal analysis and other nondestructive evaluation (NDE) techniques which apply input signals to static structures in order to monitor responses; this approach allows for the measurement of both input and output response in a rotating system for evaluation. However, unlike these techniques, the new procedure allows for multiple forms of ...


Stability Analysis Of Floating Ball Bearing, T.V.V.L. Rao, Jerzy Sawicki 2012 Birla Institute of Technology and Science

Stability Analysis Of Floating Ball Bearing, T.V.V.L. Rao, Jerzy Sawicki

Jerzy T. Sawicki

Conventional disk drive motors supported on ball bearings (BBs) cause nonrepeatable runout (NRRO) due to the surface imperfections on balls and raceways. NRRO is a source of track misregistration between head and disk that inhibits high track density in a hard disk drive. Fluid dynamic bearings with herringbone grooves either on the rotating or stationary surfaces are a suitable replacement for conventional ball bearings. Herringbone grooved bearings have considerably lower noise level than ball bearings and have better stability compared to plain journal bearings at concentric operating position. However, herringbone-grooved patterns are difficult to manufacture because groove depth is of ...


A Microfluidic Reactor For Energy Applications, Luke T. Wagner, Jie Yang, Susan Ghobadian, Reza Montazami, Nicole N. Hashemi 2012 Iowa State University

A Microfluidic Reactor For Energy Applications, Luke T. Wagner, Jie Yang, Susan Ghobadian, Reza Montazami, Nicole N. Hashemi

Mechanical Engineering Publications

Miniature microbial fuel cells have recently drawn lots of attention as portable power generation devices due to their short startup time and environmentally-friendly process which could be used for powering small integrated biosensors. We designed and fabricated a microbial fuel cell in a microfluidic platform. The device was made in polydimethylsiloxane with a volume of 4 μL and consisted of two carbon cloth electrodes and proton exchange membrane. Shewanella Oneidensis MR-1 was chosen to be the electrogenic bacterial strain and inoculated into the anode chamber. Ferricyanide was used as the catholyte and pumped into the cathode chamber at a constant ...


Electrohydrodynamic Enhancement Of Heat Transfer And Mass Transport In Gaseous Media, Bulk Dielectric Liquids And Dielectric Thin Liquid Films, Seyed Reza Mahmoudi 2012 The University of Western Ontario

Electrohydrodynamic Enhancement Of Heat Transfer And Mass Transport In Gaseous Media, Bulk Dielectric Liquids And Dielectric Thin Liquid Films, Seyed Reza Mahmoudi

Electronic Thesis and Dissertation Repository

Controlling transport phenomena in liquid and gaseous media through electrostatic forces has brought new important scientific and industrial applications. Although numerous EHD applications have been explored and extensively studied so far, the fast-growing technologies, mainly in the semiconductor industry, introduce new challenges and demands. These challenges require enhancement of heat transfer and mass transport in small scales (sometimes in molecular scales) to remove highly concentrated heat fluxes from reduced size devices. Electric field induced flows, or electrohydrodynamics (EHD), have shown promise in both macro and micro-scale devices.

Several existing problems in EHD heat transfer enhancements were investigated in this thesis ...


Acoustic Emission Detection Of Metals And Alloys During Machining Operations, Jameson K. Nelson 2012 Purdue University

Acoustic Emission Detection Of Metals And Alloys During Machining Operations, Jameson K. Nelson

Purdue Polytechnic Masters Theses

Nelson, Jameson K. M.S., Purdue University, May 2012. Acoustic Emission Detection of Metals and Alloys During Machining Operations. Major Professor: Rodney G. Handy.

Practical correlation between material deformation attributes and theoretical concepts of machining has proven difficult to attain. The purpose of this study was to further explore trends and relationships using acoustic emission detection of materials undergoing single-point lathe turning machine processes. The majority of machining experiments that incorporate acoustic emissions focuses on tool degradation for the purposes of optimizing consumables required to manufacture mechanical devices. Experiments were implemented varying recording location, mechanical barrier condition, and machine parameters ...


Wear Behavior Of Tini And Tini-Tic Clads Deposited By Tig Surfacing, Masoud Harooni, Morteza Shamanian, Alireza Fadaei Tehrani 2012 Southern Methodist University

Wear Behavior Of Tini And Tini-Tic Clads Deposited By Tig Surfacing, Masoud Harooni, Morteza Shamanian, Alireza Fadaei Tehrani

Masoud Harooni

This paper deals with the investigation of wear behavior of TiNi and TiNi-TiC clads applied to plain carbon steel by tungsten inert gas (TIG) surfacing process. In this regard, ball milled Ti-Ni and Ti-Ni-C powder mixtures were used as feedstock materials. The clad layers were investigated using X-ray diffractometery (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), hardness measurements and reciprocating wear tests. The results of microhardness measurements indicated that hardness values of TiNi-TiC composites were higher than those of TiNi by approximately 100HV. It was also shown that the wear behavior of TiNi-TiC clads was better than that ...


Experimental Benchmarking Of Surface Textured Lip Seal Models, Wei Li 2012 University of Kentucky

Experimental Benchmarking Of Surface Textured Lip Seal Models, Wei Li

Theses and Dissertations--Mechanical Engineering

A thorough investigation on the existing hydrodynamic lubrication theories and the reverse pumping theories for the conventional lip seal is conducted. On that basis, the algorithms and the methods used in the numerical modeling of the conventional lip seal are modified and applied to the study of the lip seal running against surface textured shafts. For each step of the study, the numerical model is benchmarked against the experimental results. Important physical mechanisms which explain the reverse pumping ability of the triangular surface structures are revealed. Meanwhile, the accuracy of the numerical model is tested. In general, the numerical simulation ...


The Morphotropic Phase Boundary In The (1-X)Pbzro3–X[0.3bi(Zn1/2ti1/2)O3–0.7pbtio3] Perovskite Solid Solution, T. Sareein, W. Hu, Xiaoli Tan, R. Yimnirun 2012 Chiang Mai University

The Morphotropic Phase Boundary In The (1-X)Pbzro3–X[0.3bi(Zn1/2ti1/2)O3–0.7pbtio3] Perovskite Solid Solution, T. Sareein, W. Hu, Xiaoli Tan, R. Yimnirun

Materials Science and Engineering Publications

Ceramics in the (1-x)PbZrO3–x[0.3Bi(Zn1/2Ti1/2)O3–0.7PbTiO3] solid solution system with 0.48  x  0.56 were investigated. A morphotropic phase boundary separating rhombohedral and tetragonal perovskite phases was identified at x = 0.52. This composition displays the maximum remanent polarization Pr of 40.7 μC/cm2 and the best piezoelectric coefficient d33 of 311 pC/N in the pseudo-binary system. However, the Curie temperature Tc for this MPB composition is 291 °C, much lower than initially expected.


Mechanical Confinement: An Effective Way Of Tuning Properties Of Piezoelectric Crystals, Mie Marsilius, Josh Frederick, Wei Hu, Xiaoli Tan, Tosten Granzow, Pengdi Han 2012 Technische Universität Darmstadt

Mechanical Confinement: An Effective Way Of Tuning Properties Of Piezoelectric Crystals, Mie Marsilius, Josh Frederick, Wei Hu, Xiaoli Tan, Tosten Granzow, Pengdi Han

Materials Science and Engineering Publications

Using <001>-oriented Pb(Mg1/3Nb2/3)O3–PbTiO3 ferroelectric single crystals as a model material, the impact of mechanical confinements on polarization hysteresis, coercive field, and remanent polarization of relaxor-based piezocrystals is investigated. Comparative studies are made among rhombohedral and tetragonal single crystals, as well as a polycrystalline ceramic, under uniaxial and radial compressive pre-stresses. The dramatic changes observed are interpreted in terms of the piezoelectric effect and possible phase transitions for rhombohedral crystals, and ferroelastic domain switching and the piezoelectric effect for tetragonal crystals. Under radial compressive stresses, the coercive field for the rhombohedral ...


Structure Evolution And Dielectric Behavior Of Polystyrene-Capped Barium Titanate Nanoparticles, H.Z. Guo, Yaroslav Mudryk, M.I. Ahmad, X.C. Pang, L. Zhao, M. Akinc, Vitalij K. Pecharsky, Nicola Bowler, Z.Q. Lin, Xiaoli Tan 2012 Iowa State University

Structure Evolution And Dielectric Behavior Of Polystyrene-Capped Barium Titanate Nanoparticles, H.Z. Guo, Yaroslav Mudryk, M.I. Ahmad, X.C. Pang, L. Zhao, M. Akinc, Vitalij K. Pecharsky, Nicola Bowler, Z.Q. Lin, Xiaoli Tan

Materials Science and Engineering Publications

Polystyrene-capped barium titanate (BaTiO3) nanoparticles with sizes of 11 nm and 27 nm were prepared using amphiphilic star-like diblock copolymer templates. The crystal structure evolution of these nanoparticles over a wide temperature range (10-428 K) was investigated by powder X-ray diffraction. The Rietveld refinement indicates that the abrupt structural transitions observed in micron-sized powders become broad as particle size is reduced to a few tens of nanometers. The orthorhombic phase (Amm2) is observed in the range of 10-388 K, coexisting with the rhombohedral phase (R3c) at lower temperatures and with the tetragonal phase (P4mm) at higher temperatures. At room temperature ...


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