bluuebunny/crossref_metadata_2025 huggingface dataset:
Assessment of the Feasibility of Biodiesel Blends for Small Commercial Engines
Authors: Tanner Matthew , Stryker Peter , Brahma Indranil
Published: July 2013

Petroleum supply and environmental issues have increased interest in renewable low polluting alternative fuels. Published test results generally indicate decreased pollution with similar power output from internal combustion engines burning alternative fuels. More specifically, diesel engines burning biodiesel derived from plant oils and animal fats, not only reduce harmful exhaust emissions, but are renewable and environmentally friendly.

A literature review found little previous research with biodiesel in small commercial diesel engines. This paper presents the research that was conducted to study the effect of biodiesel/diesel fuel blends on engine performance and emissions for a Yanmar L100 EE (7.1 kW) engine. This is a standard commercial grade diesel engine used for small equipment such as generators.

Independent engine dynamometer and emissions testing were performed to validate the lower emission claims and assess the feasibility of alternative fuels. A testing apparatus capable of making relevant measurements was designed, built and used to perform this study.

Fuel blends used included B2, B20, B40, B60, B80, and B100 where the biodiesel component of the blend was a commercial product. An analysis of the fuel showed large percentages of linoleic acid, palmitic acid and stearic acid which is typical for a blend of soybean oil and beef tallow.

Test were performed at a constant torque (95 % of the continuously rated value) and variable engine speeds. Test results included calculated values of BMEP, BSFC, thermal efficiency, air mass flow rate, air fuel ratio, corrected NOx, energy lost to exhaust, and heat rejection, and measured values of unburned hydrocarbons, carbon monoxide, and carbon dioxide.

Results indicate an increase in thermal efficiency compared to standard diesel and significant reductions of unburned hydrocarbons and carbon monoxide at all engine speeds. Brake specific fuel consumption increased with increasing percent biodiesel consistent with the decreased energy content of blended fuel. Significantly, there were small but consistent reductions in corrected NOx for all blends at all speeds. We posit possible explanations for these results, which are contrary to the published results for larger engines which show an increase in NOx for biodiesel blends.
Improvement in Lean Homogenous Spark-Ignition Combustion With Pulsed Energy Spark Plug
Authors: Jacobs Timothy J. , Camilli Louis J. , Gonnella Joseph E.
Published: July 2013

This article describes a study involving new spark plug technology, referred to as pulsed energy spark plug, for use in igniting fuel-air mixtures in a spark ignition internal combustion engine. The study involves precisely controlled constant volume combustion bomb tests. The major defining difference between the pulsed energy spark plug and a conventional spark plug is a peaking capacitor that improves the electrical-to-plasma energy transfer efficiency from a conventional plug’s 1% to the pulsed energy plug’s 50%. Such an increase in transfer efficiency is believed to improve spark energy and subsequently the ignition time and burn rate of a homogeneous, or potentially stratified, fuel-air mixture.

The study observes the pulsed energy plug to shorten the ignition delay of both stoichiometric and lean mixtures (with equivalence ratio of 0.8), relative to a conventional spark plug, without increasing the burn rate. Additionally, the pulsed energy plug demonstrates a decreased lean flammability limit that is about 14% lower (0.76 for conventional plug and 0.65 for pulsed energy plug) than that of the conventional spark plug. These features — advanced ignition of stoichiometric and lean mixtures and decreased lean flammability limits — might qualify the pulsed energy plugs as an enabling technology to effect the mainstream deployment of advanced, ultra-clean and ultra-efficient, spark ignition internal combustion engines. For example, the pulsed energy plug may improve ignition of stratified-GDI engines. Further, the pulsed energy plug technology may improve the attainability of lean-burn homogeneous charge compression ignition combustion by improving the capabilities of spark-assist. Finally, the pulsed energy plug could improve natural gas spark ignition engine development by improving the ignition system. Future work could center efforts on evaluating this spark plug technology in the context of advanced internal combustion engines, to transition the state of the art to the next level.
Influence of Couple Stress Lubricant on the Performance of Orifice Compensated Non-Recessed Hole-Entry Hydrostatic/Hybrid Journal Bearing
Authors: Sharma Satish C. , Ram Nathi
Published: July 2013

The lubricants are generally additized in order to enhance their lubricating properties. As a consequence of this, they exhibit nonlinear relationship between the shear stress and shear strain. One class of lubricants which has received considerable attention in recent years is the couple stress lubricants. The study of couple stress fluid flows has been the subject of increased interest owing to its widespread industrial and scientific applications such as synthetic fluids, polymer-thickened oils, liquid crystals and animal bloods. The present work is therefore aimed to study analytically the influence of couple stress lubricant on the performance of an orifice compensated non-recessed hole-entry hydrostatic/hybrid journal bearings. The modified Reynolds equation based on Stoke’s couple stress fluid theory has been solved by using the Finite Element Method. The numerically simulated results have been presented for various valves of couple stress parameters and external loads. The numerically simulated results reveal that the influence of couple stress lubricant increases the value of minimum fluid film thickness at constant value of external load for hybrid journal bearing vis-a-vis Newtonian lubricant. Further, it has been observed that the value of direct fluid film damping coefficient (C22) is larger for hydrostatic journal bearing lubricated with couple stress lubricant.
From Full Film Lubrication to Local Film Breakdown: A Molecular Dynamics Approach
Authors: Savio D. , Fillot N. , Vergne P. , Zaccheddu M.
Published: July 2013

The transition from full film lubrication to local film breakdown is studied using molecular dynamic simulations. In particular, the behavior of the confined lubricant and the friction are analyzed as a function of the number of molecules in the contact, surface wettability and nanoroughness. When the film thickness is progressively reduced, smooth wettable surfaces feature minima and maxima in friction corresponding to ordered and disordered states of the lubricant respectively. Wall slip occurs for non wettable smooth surfaces, which limits the shear stress to a low constant value. Finally, nanorough surfaces frustrate lubricant ordering and wall slip, thus resulting in high friction, which reaches its maximum when the surfaces come in contact.
Formulation of a Biobased Gear Oil Utilizing Boron Technology
Authors: Doll Kenneth M. , Heise Glenn L. , Myslinska Malgorzata , Sharma Brajendra K.
Published: July 2013

A new additive was produced from a natural oil and boron. The synthesis involves the use of the epoxidized form of soybean oil which then undergoes a catalytic ring opening to produce the additive material. Due to their remaining triacylglycerol structure, the products are highly compatible with bio-based lubricants and due to their covalent boron attachments, show effective properties for the reduction of wear.

Some performance examples: Using a traditional Falex 4-ball wear test, the scar diameter observed in a soybean oil lubricant could be reduced from 0.61 mm to 0.41 mm by the inclusion of 1% or the additive. A second generation additive, while not as effective at reducing wear, was able to increase the oxidation onset temperature of soybean oil under pressurized oxygen by 14 °C.

Next, these additives were tested in a formulation of biobased gear oil composed of heat treated soybean oil and synthetic esters. In the best formulation, these additives were able to surpass the oxidation onset of a gear oil that was formulated with commercially available additives, while giving nearly as good of performance by wear scar analysis. This oxidation onset value, of 258 °C, approaches that of off-the-shelf gear oils.

Overall, these new additives are strong performers which can be made using simple chemistry. Their properties combined with their high biobased content are valuable assets in the search for biobased lubricants and gear oils.
Diesel Engine Turbocharger Stabilized With Novel Tilting Pad Bearing Design
Authors: Kirk R. Gordon , Enniss Matthew , Freeman Daniel , Brethwaite Andrew
Published: July 2013

Many high speed turbochargers operate with limit cycle vibration as a result of fluid-film instability. This problem has been under investigation for the past seven years. Only now has a turbocharger with fluid film bearings been run to full speed and loaded, with essentially no bearing induced sub-synchronous vibration. The goal of this research was to have a stable synchronous response with a minimum of non-synchronous contribution excited only by the engine dynamics and exhaust pressure pulsations. Previous papers have documented experimental results of the fixed geometry bearing designs. This paper documents a new, modified tilting pad bearing concept that has replaced the fixed geometry bushings with minimal modifications to the stock bearing housing. The summary of the on-engine testing over the past year is documented in this paper.
Friction Process of Superlubricity
Authors: Li Jinjin , Zhang Chenhui , Luo Jianbin
Published: July 2013

The friction process of superlubricity (μ = 0.004) obtained by phosphoric acid solution has been investigated by a traditional tribometer. The evolution of friction coefficient with time indicates that the friction process of superlubricity is divided into three stages, i.e. friction reducing rapidly process, low friction process and superlubricity process. The feature of these three stages is discussed according to several experiments. The result indicates that the contact region in superlubricity state is a three layer structure formed after the first stage and the second stage, which is the origin of ultra-low friction.
The Validity of the Compressible Reynolds Equation for Gas Lubricated Textured Parallel Slider Bearings
Authors: Qiu Mingfeng , Bailey Brian , Stoll Rob , Raeymaekers Bart
Published: July 2013

The Navier-Stokes and compressible Reynolds equations are solved for gas lubricated textured parallel slider bearings under hydrodynamic lubrication for a range of realistic texture geometry parameters and operating conditions. The simplifying assumptions inherent in the Reynolds equation are validated by comparing simulation results to the solution of the Navier-Stokes equations. Using the Reynolds equation to describe shear driven gas flow in textured parallel slider bearings is justified for the range of parameters considered.
Tribology of Insulation Materials Within Implantable Cardioverter-Defibrillator Leads
Authors: Wilson Charles , Himes Adam
Published: July 2013

Insulation wear in implanted cardioverter-defibrillator (ICD) leads may result in serious failure modes, including inappropriate or missing therapy. Tests performed on a custom apparatus developed to simulate in-vivo loading showed order of magnitude differences in specific wear rate between materials commonly used in ICD leads. Wear rates were also dependent on load, suggesting that design and application differences may further differentiate performance between materials.
Stress Relaxation of Articular Cartilage in Unconfined Compression
Authors: Smyth Patrick , Green Itzhak , Jackson Robert , Hanson R. Reid
Published: July 2013

The articular cartilage function is to allow the bones in a joint to move without causing excess friction and damage. When this cartilage becomes damaged, the supportive and lubricating mechanisms break down, leading to injuries which can be permanent or take extended periods of time for recovery. Because of its importance in general health and body mobility, the unique lubricating properties of cartilage have been studied for many decades. Many current theories exist to characterize the biphasic and triphasic nature of cartilage; however, an important reason that cartilage is so effective is its viscoelastic nature, which allows elastic and dissipative mechanisms to exist simultaneously. It is desired to derive the material properties of cartilage in order to better understand its mechanical effectiveness. Utilizing a CETR-UMT-3 Tribometer, stress relaxation experiments will be performed on freshly harvested equine cartilage plugs that remain hydrated in a fluid bath. Viscoelastic models, such as the Prony series and fractional derivative, are applied to the experimental data to determine the storage and loss moduli of the sample explants. The storage and loss information characterizes the mechanical response of cartilage, and provides insight into the effectiveness and longevity of biological joints. A comparison will be made between joints that experience similar loads, but undergo different relative motions, to determine if the mechanical properties of cartilage are tailored to joint function. Osteoarthritic cartilage will also be explored for deviations in viscoelastic behavior compared to healthy cartilage. Ultimately, it is hoped that a viscoelastic characterization of articular cartilage will lead to insight into the precursors of osteoarthritis, more advanced prosthetics, and biomimetric applications such as the integration of flexible surfaces in mechanical systems.
Tribological Property Analyses of DLC Films on Ceramic Ball Surfaces With 3-D FEA Method and Experiments
Authors: Zhang Chuanwei , Gu Le , Zheng Dezhi
Published: July 2013

Diamond-like carbon (DLC) films are excellent candidates to improve tribological properties of silicon nitride (Si3N4) ceramic elements. Particular attentions have been paid to the preparation and analysis of DLC films on rings and discs. However, few researches on fabrication of DLC films on ball surfaces were carried out, especially on ceramic ball surfaces, because it is hard to achieve uniform coatings on ball surfaces.

In this paper, DLC films on ceramic ball surfaces were studied with both experiment and FEA method. DLC films were deposited on Si3N4 ceramic ball and disc surfaces with plasma immersion ion implantation and deposition techniques (PIII-D). Surface topography of ceramic balls before and after coated with DLC films showed that DLC films on ceramic ball surfaces were uniform. Tribological tests under dry friction were conducted with a ceramic ball sliding against ceramic disc and, alternatively, one of the two surfaces was coated with DLC films. The tests demonstrated that DLC films on disc surfaces were worn, while ball surface films were partly flaked.

3-D FEA models of ceramic ball sliding against ceramic disc were built and the ceramic ball/disc was coated with DLC films alternatively. DLC films were supposed to be bonded with ceramic substrates. The FEA stress fields in DLC films and on film/substrate interface showed that DLC films had great effects on stress distribution due to the low frictional coefficient and material difference from substrates. The friction force caused an increment of the stress near surfaces during sliding process, and the material difference leaded to discontinuous stress distribution on film/substrate interface. The shear stress on film/substrate interface was very slightly different between DLC films coated on ceramic balls and discs. Under almost the same shear stress, the flakes and wear of DLC films were mainly determined on the adherence of DLC films to ceramic substrates.
Molecular Dynamics Simulation of a Rigid Sphere Indenting a Copper Substrate
Authors: Jia Ding , Li Longqiu , Ovcharenko Andrey , Song Wenping , Zhang Guangyu
Published: July 2013

Three-dimensional molecular dynamics (MD) simulation is used to study the atomic-scale indentation process of a spherical diamond tip in contact with a copper substrate. In the indentation simulations, the force-displacement curve is obtained and compared with a modified elastic solution of Hertz. The contact area under different indentation depths is also investigated. The force-displacement curve under different maximum indentation depths is obtained to investigate elastic-plastic deformation during the loading and unloading processes.
New Generation of Water Lubricated Foil Bearing: Numerical Models and Experimental Verification
Authors: Olszewski Artur , Wodtke Michał , Gawarkiewicz Rafał
Published: July 2013

The paper presents a new idea of foil water-lubricated bearing and the methodology of hydrodynamic characteristics calculations. Two different computer models were built in order to assess the theoretical characteristics of these bearings. Firstly a structural model coupled with a hydrodynamic fluid model which takes into account: fluid flow in the deformed fluid gap — a specific design of bearing support and the friction in bearing support. The second model is based on the fluid structure interaction simulation. Due to the fact that it is necessary to define physical properties of the materials for computer models, special tribology and stiffness tests of actual materials intended to be used in the prototype bearing were performed.

The test rig was modernised by installing pressure sensors on bush perimeter in two parallel planes in order to verify the method of the calculation of the bearing.
Properties Comparison of Two Water Lubricated Rubber Bearings Based on Experimental Test
Authors: Litwin Wojciech , Olszewski Artur
Published: July 2013

Water lubricated rubber bearings are used from many years in ship building and other industry because of their advantages such as: long serviceable life, low coefficient of friction, long life of shaft sleeve, good vibration damping, good abrasion resistance, low maintenance required, grit particles and other abrasives are expelled through the grooves [1,2,3,4].
Transient Thermo-Mechanical Plowing Contact Between Rigid Sphere and Elastic-Plastic Sphere
Authors: Song Wenping , Ovcharenko Andrey , Li Longqiu , Zhang Guangyu , Talke Frank E.
Published: July 2013

Transient thermo-mechanical contact between a rigid sphere sliding over an elastic-plastic sphere with a larger radius is studied using finite element analysis. Plastic deformation and temperature rise in the contact zone between the two spheres are investigated.
The Contribution of a Sliding Velocity to EHL Film Thickness Distribution
Authors: Omasta Milan , Krupka Ivan , Hartl Martin
Published: July 2013

In general contact conditions, the surface velocities are variously oriented, thus the entrainment and sliding velocity act at different directions. The effects of magnitude and direction of the sliding velocity in elastohydrodynamic lubrication (EHL) circular contact have been investigated. Film thickness distribution has been obtained using thin-film colorimetric interferometry. It has been found that direction of sliding velocity with respect to entrainment velocity play a role in film thickness distribution, particularly at high slide-to-roll ratios. A superposition of the effects of a pure rolling and of an opposite sliding has been considered. The pure rolling condition creates typical horse-shoe shaped film, whereas under the opposite sliding condition (i.e. zero entrainment velocity) conical depression in the central area of Hertzian contact called “dimple” has been observed.
The Role of Laser Surface Textured Patterns on Friction in Reciprocating Contacts
Authors: De la Cruz M. , Gore M. , Morris N. , Rahnejat H.
Published: July 2013

The paper presents the development of a new reciprocating friction measurement test rig. Additionally, laser surface texturing (LST) techniques are introduced and a set of typical experimental results is presented. It is shown that the introduction of textured areas can result in significant reduction in lubricated conjunctional friction of a straight ring segment-to-a flat substrate.
The Effects of Floor Roughness on Shoe-Floor Friction Adhesion and Hysteresis
Authors: Cowap Matthew , Beschorner Kurt
Published: July 2013

Slip and fall accidents are a major source of occupational accidents. The coefficient of friction (CoF) that is required for gait is approximately 0.2. Floor roughness has been demonstrated to affect the available CoF. Building on this knowledge, this research aims to investigate the effect of changing floor roughness on two components of friction: adhesion and hysteresis. The experiments were carried out using a custom developed pin-on-disk type tribometer. Two common types of rubber shoe material, with Shore A hardness 50 and 95, were slid over ceramic tiles that were prepared to different roughness levels. The tiles were abraded using aluminum oxide media (commonly called “sand blasting”). Three levels of roughness were achieved, measured using the average peak height (Rz) with a stylus profilometer: 16.6 μm, 24.3 μm, and 34.6 μm. The experiments were conducted at 0.01 m sec-1 at a contact pressure of 266.1 kPa under ambient conditions to specifically examine the role of adhesion and hysteresis in the absence of hydrodynamic effects. The coefficient of friction was recorded without lubricant (dry) and lubricated with: 2% detergent solution, canola oil, and SAE 75W140 gear oil. Hysteresis was measured with SAE 75W140 because the high lubricity of the gear oil minimizes adhesion. Adhesion in dry and wet conditions was measured by subtracting the hysteresis from the coefficient of friction. Hysteresis was found to increase from 0.101 to 0.358 for the hard rubber and from 0.269 to 0.611 for the soft rubber when floor roughness was increased from 16.6 μm and 34.6 μm. Higher roughness was also associated with a decrease in dry adhesion from 0.651 to 0.277 for the hard rubber and from 0.435 to 0.041 for the soft rubber. Wet adhesion decreased from 0.285 to 0.049 for soft rubber on detergent. Canola oil, for both hard and soft, and detergent combined with hard rubber did not make a significant difference in the adhesion available. Hysteresis, which is a more robust form of friction in the presence of fluids, was found to be positively correlated with floor roughness while adhesion was negatively correlated with roughness. This indicates that increased floor friction is associated with better floor slip-resistance in the presence of fluids. Abrasively blasting floor tiles to increase the roughness of the floor surface, may lead to improved boundary lubrication friction, particularly when accompanied by soft shoe materials.
A Fast-Solving Semi-Analytical Solution Method for Contact Problems Involving Multi-Layered Inhomogeneously Elastic Solids
Authors: Chidlow Stewart , Teodorescu Mircea
Published: July 2013

This work is concerned with the derivation of an iterative solver which allows the accurate estimation of both the contact half-width and contact pressure when an inhomogeneouly elastic solid comprising a homogeneous coating and substrate joined by a graded layer is indented by a rigid punch. A selection of numerical results are then presented illustrating the accuracy of this model.
Modeling Low-Viscosity 1st Compression Ring EHL at Large Radial Clearance in Initial Engine Start Up
Authors: Qasim Syed Adnan , Naseer Rashid , Ghafoor Abdul , Malik M. Afzaal
Published: July 2013

In normal IC engine operation 1st compression ring sustains thermal loads effectively. At large radial clearance in low-speed engine start up it has to act as effective seal against thermal loading. Absence of elastohydrodynamic lubricating (EHL) film and secondary displacements expose the ring to adhesive wear in initial engine start up. Isothermal hydrodynamic and EHL models of parabolic-faced ring are developed numerically after incorporating secondary dynamics of piston assembly at a low engine start up speed. Reynolds equation is solved to generate hydrodynamic pressures and film profiles in 4-stroke cycle. In EHL model inverse solution technique and elastic displacements of ring and liner are employed to generate pressures and film profiles. The simulation results suggest that a large ring-to-bore clearance increases eccentricity and affects EHL of 1st compression ring when a low-viscosity grade oil is used in initial engine start up.
A Mechanistic Approach to Predicting the Friction Behaviour of Human Skin
Authors: van Kuilenburg Julien , Masen Marc A. , van der Heide Emile
Published: July 2013

In this work, analytical models available from contact mechanics theory having a proven record in mechanical engineering were used to develop a model predicting the friction behavior of human skin.

A multi-scale contact model was developed in which the contact parameters are calculated at three levels, each level characterized by its elastic behavior and geometry. For a product part in contact with the so-called hairy skin the skin topography can be described as being composed of spherical contacts, whereas for the finger in contact with a product surface the fingerprint ridges are modeled as annulus shaped line contacts.

Sliding friction was measured in vivo between the skin and different surface textures produced using ultra-short pulsed laser technology. The results observed during in vivo experiments are very well explained by the developed model, which predicts the friction as a function of product geometry, asperity geometry and normal load.
Single Particle Interaction Properties: Investigations on the Coefficient of Restitution and Coefficient of Friction
Authors: Marinack Martin C. , Dougherty Patrick S. M. , Higgs C. Fred
Published: July 2013

Understanding granular flows has always been important for predicting natural phenomena such as rockslides and soil erosion, as well as industrial processes such as coal-based fossil fuel systems and solids processing. As such, it becomes important to understand granular flows from both a classical granular flow and tribological perspective. Inherently important in the study of granular flows is the study of the individual particle level interactions, which define the global behavior of the flow. The current work examines both the coefficient of restitution (COR) and coefficient of friction (COF) for various material combinations. COR and tribological experiments are performed on various sphere and plate (disk) materials, such as low carbon steel, tungsten carbide (WC), and NITINOL 60.
Efficient Numerical Modeling of Hertzian Line Contact for Material With Inhomogeneities
Authors: Jin Xiaoqing , Wang Zhanjiang , Zhou Qinghua , Keer Leon M. , Wang Qian
Published: July 2013

The present work proposes an efficient and general-purpose numerical approach for handling two-dimensional inhomogeneities in an elastic half plane. The inhomogeneities can be of any shape, at any location, with arbitrary material properties (which can also be non-homogeneous). To perform the numerical analysis, we first derive an explicit closed-form solution for a rectangular inclusion with uniform eigenstrain components, where the inclusion is aligned with the surface of the half plane. In view of the equivalent inclusion method, an inhomogeneity problem can be converted to a corresponding inclusion problem. In order to determine the distribution of the equivalent eigenstrain, the computational domain is meshed into rectangular elements whose resultant contributions can be efficiently computed using an efficient algorithm based on fast Fourier transform (FFT). In principle, there is no specific limitation on the type of the external load, although our major concern is the contact analysis. Parametric studies are performed and typical results highlighting the deviation of the current solution from the classical Hertzian line contact theory are presented.
Tribological Performance of Environmentally Friendly Ionic Liquid Lubricants
Authors: Reeves Carlton J. , Garvey Sarah , Menezes Pradeep L. , Dietz Mark , Jen Tien-Chien , Lovell Michael R.
Published: July 2013

Presented in this study is a new class of “greener” lubricants, room temperature ionic liquids, that represent a promising potential solution to many of the problems associated with both conventional lubricants and those based on natural oils. In this study, friction and wear tests were carried out using a pin-on-disk tribometer under ambient conditions to characterize the performance of the ionic liquids as lubricants. Specifically, ionic liquids consisting of salicylate, benzoate (common food additives) and saccharinate (an artificial sweetener) anions with conventional phosponium cations were evaluated as lubricants and compared to petroleum-based lubricants and natural oils in regards to structure and performance. The ionic liquids generally demonstrated better tribological performance than either the petroleum-based lubricants or natural oils. The mechanisms governing the chemical composition and improved tribological performance are discussed while highlighting possible industrial applications of this new class of lubricants.
An Investigation of the Steady-State Performance of a Wave Aerodynamic Thrust Bearing for High Speed Applications
Authors: Ene Nicoleta M. , Dimofte Florin
Published: July 2013

The steady-state performance of an aerodynamic double thrust wave bearing was investigated. The investigation showed that a double thrust wave bearing with an inner diameter of 15 mm and an outer diameter of 45 mm can support axial loads of 200 N at 100,000 rpm for a minimum film thickness of 3 microns. The influence of the wave bearing parameters on the bearing performance was also analyzed. The theoretical analysis was validated by experimentally testing one side of the thrust bearing. A special test rig was built for this purpose. The experimental data were close to the numerical predictions, validating the computer codes.
Performance and Failure Modes of Grease Lubricated Hybrid Ceramic Bearing in High Speed and High Temperature Condition
Authors: Zheng Dezhi , Gu Le , Wang Tingjian , Wang Liqin
Published: July 2013

Ceramic rolling element bearings have promising applications in extreme operating conditions such as high speed, high temperature, and heavy load. In this study, a hybrid silicon nitride ceramic ball bearing lubricated with high temperature grease is presented. The structure and parameters of the bearing are specially designed to satisfy the requirement of grease lubrication, high temperature and high speed conditions. A test rig was developed for the experiments of ceramic bearing performance. The experimental results show that grease lubricated ceramic bearings with fine design have excellent high speed and high temperature performance. By analyzing the operation performance and failure bearing inspection, the failure modes of grease lubricated ceramic bearings is analyzed. Thermal instability caused by the grease insufficient supply is the main factor of failure.
Experimental and Modeling Studies for Understanding Shoe-Floor-Contaminant Friction and Designing for Slip-Resistance
Authors: Beschorner Kurt
Published: July 2013

Insufficient friction at the shoe-floor interface causes a large number of slip and falling accidents each year. Developing solutions for enhancing shoe-floor-contaminant friction requires understanding the mechanisms that contribute to slippery surfaces. Over the past several years, our research group has conducted several experimental and modeling studies to reveal the critical tribological mechanisms contributing to shoe-floor-contaminant friction. This extended abstract will discuss the findings of these studies to: 1) determine the lubrication regime(s) that is/are most relevant to under-shoe conditions during slipping; 2) quantify how under-shoe conditions, shoes and flooring affect the two main contributions to boundary lubrication: adhesion and hysteresis; and 3) describe how this information can be used to design slip-resistant shoes and flooring. To identify the lubrication regime, interfacial pressures at the shoe-floor-contaminant interface were measured and coefficient of friction was monitored. Low viscous fluids and shoes with at least 2mm of tread were found to have negligible interfacial pressures and moderate friction coefficients (0.07–0.40). Untreaded shoes combined with high viscous fluids led to high interfacial pressures that supported up to 40% of the normal load and low friction coefficients (<0.01). These results suggest that mixed/elasto-hydrodynamic lubrication is relevant in some untreaded conditions but that boundary lubrication is relevant for most other conditions. In boundary lubrication, the primary factors contributing to friction are adhesion and hysteresis. Experimental data and finite element models demonstrate that hysteresis friction increases with floor roughness and the ratio of shoe to floor hardness. Adhesion friction is dependent on real area of contact and the shear stress required to break junctions. Experimental data suggests that adhesion is dependent on the fluid lubricant, sliding speed, floor roughness and shoe material. Finite element models confirm that a reduction in the real area of contact occurs with increasing floor roughness and sliding speed, consistent with the experimental adhesion effects. Ensuring that the shoe-floor-fluid interface is operating in the boundary lubrication regime requires establishing minimum tread threshold for fluid lubricants that are likely to be found in a given environment. Designing a high hysteresis shoe-floor combination is preferred because it is relatively unaffected by fluid contaminants or under-shoe conditions (i.e. sliding speed). Therefore, ensuring a minimum tread depth is used along with increasing floor roughness and shoe to floor hardness may be effective in addition to minimum tread thresholds.
Anti-Vibration Tribometer Using Viscous Damping Effect Generated by Lateral Slip
Authors: Nakano Ken , Tadokoro Chiharu , Kado Naohiro
Published: July 2013

This paper proposes a simple and novel principle for suppressing frictional vibration using viscous damping effect generated by “lateral slip” given to a typical sliding system. This principle was applied to the measurement of friction coefficient and an anti-vibration tribometer (AVT) was developed. The AVT suppressed frictional vibration caused by the negative dependence of the friction coefficient on the relative velocity, and it enabled one to measure friction coefficient accurately in the force balance between the friction force and spring force. If using the mean value of oscillating spring force to calculate friction coefficient under frictional vibration, it was found that considerable errors (e.g., approximately 30%) appears.
Spontaneous Change in Effective Viscosity of a Liquid Crystal by Surface Anchoring in an EHD Contact
Authors: Tadokoro Chiharu , Nakano Ken
Published: July 2013

The optical film thicknesses of a 0.1 mass% solution of hexadecanoic acid (HDA) in a nematic liquid crystal (i.e., 4-pentyl-4′-cyanobiphenyl (5CB)) were measured in an EHD contact by using ultrathin-film interferometry. Comparing with a 0.1 mass% solution of HDA in an ordinary isotropic liquid (i.e., polyalphaolefin), the optical film thickness of the solution was increased at middle entrainment speeds (i.e., in the mixed lubrication regime). This shows that the effective viscosity of 5CB was increased with decreasing the entrainment speed, by the surface anchoring of 5CB on the boundary films formed by HDA. Using this spontaneous change in the effective viscosity, it is believed that a smart lubrication system can be realized, which optimizes the viscosity of a liquid crystal lubricant autonomously so that the friction coefficient is minimized when the entrainment speed is changed. It should be noted that this method does not need any pretreatments of contact surfaces and any external fields (e.g., an electric field or magnetic field).
Development of the GranOO Discrete Element Platform for Dynamic Problems: Application for Tribological Application
Authors: Iordanoff Ivan , Charles Jean Luc , Andre Damien
Published: July 2013

Discrete Model is based on the description of the physical state (velocity, position, temperature, magnetic moment, electric potential ..) of a large number of discrete elements that form the media to be studied. It is not basedon a continuous description of the media. Thus, it is particularly well adapted to describe media evolution driven by discontinuous phenomena like the description of multi fracturation followed by debris flow like wear study.

Recently, the use of discrete model has been widened to face problem encountered with complex rheological behavior and/or multi-physical behavior. Multi-physical problems face complex mathematical formulation because of the mixing of different families of differential equations when continuous approach is chosen. With the discrete model, each particle has a physical state and state evolution is due to local physical particle interaction: it is often much simple to write. From the beginning of the years 2000, this method has been widely applied for the study of tribological problems. Wear has been investigated[1], thermo-mechanical behavior of a contact[2], subsurface damage due to surface polishing[4]… Recently, it has been shownhow quantitative results can be obtained with this method[4]. To help and promote research in this area, a platform GranOO has been developed under a C++ environment and is distributed under thefree GPL license. The goal of this platform is to offer to researchers, especially in the tribology domain, a numerical and easy to use environment to facilitate the access to Discrete Element simulations. The main aspect of this platform ispresented in the extended abstract and some applicationsgiven as examples. Details can be found on url www.granoo.org.
Influences of Trace Water in Hydrogen and Argon on the Tribological Properties of Pure Iron
Authors: Fukuda Kanao , Hashimoto Masaaki , Sugimura Joichi
Published: July 2013

Tribological properties of pure iron were studied in argon environments containing trace water which is controlled at the value between 1 and 10,000 ppb and virtually no oxygen. The experimental data were compared with those obtained in our previous study with the same conditions of experiment but in hydrogen. The influences of trace water were recognized in both gases and confirmed not peculiar to a hydrogen environment. The coefficients of friction and specific wear rates were different to some extent between argon and hydrogen environments. The differences were supposed to be attributed to the influences of hydrogen atoms which chemisorbed on pure iron atoms appeared on the nascent surface made by sliding. Whether hydrogen and water have synergy effect on influencing tribological properties was not clarified in this study.
Influence of Surface Roughness on Traction and Scuffing Performance of Lubricated Contacts for Aerospace and Automotive Gearing
Authors: Shon Sam , Kahraman Ahmet , LaBerge Kelsen , Dykas Brian , Stringer David
Published: July 2013

In this study, a two-disk test set-up was employed to investigate the impact of surface roughness on the performance of lubricated contacts. In an attempt to simulate contacts from automotive transmissions and rotorcraft gearboxes, roller specimens made of a typical automotive gear steel (AISI 5120) and a common rotorcraft gear steel (AISI 9310) were paired with 80W90 and MIL-PRF23699 lubricants, respectively. The specimens were subjected to various operating conditions to measure their traction and scuffing outcome (i) axially ground, (ii) chemically polished isotropic surfaces, and (iii) highly polished mirror-like surfaces.
Accuracy Study of the Flux-Corrected Transport Numerical Method Applied to Transient Two-Phase Flow Simulations in Gas Pipelines
Authors: Figueiredo Aline B. , Bueno David E. G. P. , Baptista Renan M. , Rachid Felipe B. F. , Bodstein Gustavo C. R.
Published: July 2013

The ability to produce accurate numerical simulations of transient two-phase flows in gas pipelines has long been an important issue in the oil industry. A reliable prediction of such flows is a difficult task to accomplish due to the numerous sources of uncertainties, such as the basic two-phase flow model, the flow-pattern models, the initial condition and the numerical method used to solve the system of partial differential equations. Several numerical methods, conservative or not, of first- and second-order accuracies may be used to discretize the problem. In this paper we use the flux-corrected transport (FCT) finite-difference method to solve a one-dimensional single-pressure four-equation two-fluid model for the two-phase flow that occurs in a nearly horizontal pipeline characterized by the stratified-flow pattern. Because the FCT algorithm is of indeterminate order, we use a test case to assess the spatial and time accuracies for the specific class of hyperbolic problem that we obtain with the modeling employed here. The results show that the method is first order in time and second order in space, which have important consequences on the choice of mesh spacing and time step for a desired accuracy.
Three Years Later: Conclusion of a Successful Social-Environmental Management Model to Overcome the Impacts of a Heavy Crude Oil Spill
Authors: Mendizábal Andrés , Samaniego Raúl , Aleman Miguel Angel
Published: July 2013

On February 25, 2009, OCP Ecuador S.A. faced its first major incident; an oil spill consisting of 11,700 barrels of heavy crude oil in an area of high biodiversity in eastern Ecuador. An earth movement caused stress in the pipeline that resulted in its breakage. The temporarily impacted area covered 30 hectares of soil and gravel along 180 kilometers of three rivers that form the high watershed of the Amazon River; these rivers are the Santa Rosa, Quijos and the Coca.

A paper describing the model implemented to manage the emergency, clean up and remediation activities was presented during the 2010 International Pipeline Conference. Now, 3 years later, this paper presents the final conclusions and lessons learned once the remediation, approval process and subsequent monitoring have been completed.
Development of Welding Procedures for X90-Grade Seamless Pipes for Riser Applications
Authors: Nagayama Hiroyuki , Hamada Masahiko , Mruczek Mark F. , Vickers Mark , Hisamune Nobuyuki , Fukuba Tetsuya , Arredondo Archie
Published: July 2013

Ultra-high strength seamless pipes of X90 and X100 grades have been developed for deepwater or ultra-deepwater applications. Girth welding procedure specifications (WPSs) should be developed for the ultra-high strength pipes. However, there is little information for double jointing welding procedure by using submerged arc welding process for high strength line pipes.

This paper describes mechanical test results of submerged arc welding (SAW) and gas shielded flux cored arc welding (GSFCAW) trials with various welding consumables procured from commercial markets. Welds were then made with typical welding parameters for riser productions using high strength X90 seamless pipes.

The submerged arc weld metal strength could increase by increasing alloy elements in weld metal. The weld metal with CE (IIW) value of 0.74 mass% achieved fully overmatching for the X90 pipe. The weld metal yield strength (0.2% offset) was 694 MPa, and the ultimate tensile strength was 833 MPa. It was also confirmed that the reduction of boron in weld metal can improve low temperature toughness of high strength weld metal. Furthermore, it was confirmed that the HAZ has excellent mechanical properties and toughness for riser applications.

In this study GSFCAW procedures were also developed. GSFCAW can be used for joining pipe and connector material for riser production welding. The weld metal with a CE (IIW) value of 0.54 mass% could meet the required strength level for X90-grade pipe as specified in ISO 3183. Cross weld tensile testing showed that fractures were achieved in the base metal. Good Charpy impact properties in weld metal and HAZ were also confirmed.
Integrity Assessment of API 5L X65 and X70 Pipelines With Mechanical Damages
Authors: Yeom Kyu Jung , Lee Yong Kwang , Oh Kyu Hwan , Kim Cheol Man , Kim Woo Sik
Published: July 2013

Gas pipelines with mechanical damages could affect the structural integrity and causes local stress and strain concentration. Failures in gas pipeline as leakages that could affect the supply of gas, loss of production, and environmental pollution. It is important to determine if pipelines are fitness-for-service. ASME B31G code is still widely used criterion although the assessment method is the conservative method. Further examinations are needed on the effects of material grade and pipeline shape on the burst pressure of damaged pipelines. The goal of this paper is to predict the failure pressure of mechanical damaged made of API X65 and X70 pipelines, by conducting full scale burst tests and finite element analysis (FEA). Different pipeline grades, effects of gouges, and dent depths were considered for an integrity assessment. The full scale burst tests were performed for pipelines with artificial mechanical damage. The gouge defect was made in a V-notch shape and the dented pipeline was generated using a ball shaped indenter that was pressed into the pipe. A three dimensional FEA was performed to obtain the burst pressure of a pipe with gouge and dent defects as a function of defect depth and length. A FEA was used to simulate the and externally damaged pipes under internal pressure. Failure pressure was predicted with stress based and strain based assessments by the finite element method (FEM).
Implementing an Integrated Pipeline Integrity Management System (PIMS): Case Study
Authors: Dresie Steven
Published: July 2013

This case study will examine the implementation of an integrated suite of pipeline integrity management software tools and discuss related challenges during configuration and rollout phases. In this case, pipeline facility data was migrated from paper sources into a centralized database where it is regularly maintained and provides basis for related operations and integrity management components. Existing integrity management procedures and guidelines formed the core specifications for configuration of engineering assessment software tools. Using these documents the software suite now standardizes and automates the processing of ILI data, condition assessment, risk assessment and ECDA (NACE SP0502) management. The system produces a documented integrity plan customized to report specified key performance indicators and is integrated with the enterprise work order management system. The results of the engineering assessments and planning are maintained in the enterprise database and used to power web-based reporting available to a wide range of personnel inside the organization. Challenges include addressing gaps in data, bringing procedural documents and operating groups together, applying the system to existing operations, and ongoing support. This case study is intended for operators considering an integrated pipeline integrity management software solution or looking to improve the system currently in place inside their organization.