A Study of the Mechanism of Lubrication in Porous Journal Bearings: Effects of Dimensionless Oil-Feed Pressure on Frictional Characteristics

1995 ◽  
Vol 117 (2) ◽  
pp. 291-296 ◽  
Author(s):  
Satoru Kaneko ◽  
Yuji Hashimoto
Keyword(s):  
Transition Point ◽  
Journal Bearings ◽  
Hydrodynamic Regime ◽  
Feed Pressure ◽  
Mixed Regime ◽  
Initial Stage ◽  
The Coefficient Of Friction ◽  
Friction Curve ◽  
The Relationship ◽  
Lubrication Conditions

The frictional characteristics of a porous bronze bearing are investigated experimentally under hydrodynamic and mixed lubrication conditions. The results show that under the same value of dimensionless oil-feed pressure pˆs, the relationship between the coefficient of friction μ and the Sommerfeld number S can be represented by a single friction curve extending from the hydrodynamic regime to the mixed regime. With decreasing S, μ decreases in the hydrodynamic regime and then steeply increases in the initial stage of the mixed regime. However, at lower values of S, μ becomes steady and its value remains almost the same for various pˆs. The value of S at the transition point from the hydrodynamic regime to the mixed regime is significantly affected by pˆs, becoming smaller for higher pˆs. To estimate μ in the mixed regime, a simple frictional model is proposed on the basis of the assumption that the load supported by the fluid film and the coefficient of fluid friction in the mixed regime are determined by the oil film extent and that they are the same as those at the transition point. The calculated values of μ based on the model are found to approximately agree with the experimental results.

scholarly journals A Method for Monitoring Lubrication Conditions of Journal Bearings in a Diesel Engine Based on Contact Potential

2020 ◽  
Vol 10 (15) ◽  
pp. 5199
Author(s):  
Biao Wan ◽  
Jianguo Yang ◽  
Sicong Sun
Keyword(s):  
Diesel Engine ◽  
Journal Bearing ◽  
Hydrodynamic Lubrication ◽  
Journal Bearings ◽  
Asperity Contact ◽  
Contact Potential ◽  
Axis Orbit ◽  
Lubrication Condition ◽  
The Relationship ◽  
Lubrication Conditions

Wear of the journal bearings in a diesel engine is usually caused by asperity contact. Increased contact potential is caused by the asperity contact between the journal bearing and the shell. This paper analyzes the relationship between the contact potential and asperity contact and presents a method based on contact potential to monitor the bearing wear caused by asperity contact. A thermo-elastic hydrodynamic lubrication (THL) model of the journal bearing on the test bench was established and was verified by measuring its axis orbit. The asperity contact proportion was calculated based on this THL model, and its relationship with the measured contact potential was determined. The main contribution of this paper is to present a new method for monitoring the lubrication conditions of journal bearings in a diesel engine based on contact potential. The results showed that (a) when the minimum oil film thickness was less than 5 μm, asperity contact occurred between the bearing shell and the journal, which led to a sharp increase in contact pressure and a rapid increase in friction power consumption. Further, (b) there was a positive correlation between contact potential and asperity contact. The contact potential was greater than 0.75 mv when asperity contact occurred. These results proved that asperity contact could be accurately monitored using the contact potential, and the feasibility of using the contact potential to monitor the lubrication condition of a bearing was verified.

Experimental Investigation of Mechanism of Lubrication in Porous Journal Bearings: Part 1—Observation of Oil Flow in Porous Matrix

1990 ◽  
Vol 112 (4) ◽  
pp. 618-623 ◽  
Author(s):  
S. Kaneko ◽  
S. Obara
Keyword(s):  
Hydrodynamic Lubrication ◽  
Porous Matrix ◽  
Journal Bearings ◽  
Feed Pressure ◽  
Glass Spheres ◽  
Load Line ◽  
Oil Flow ◽  
Uniform Diameter ◽  
Lubrication Conditions ◽  
Oil Film Pressure

The oil flow in the porous matrix is experimentally investigated to explicate the mechanism of lubrication in the porous journal bearings. To visualize the flow in the porous matrix, a simplified model is used for the test bearing, whose matrix is composed of packed glass spheres having small uniform diameter. A dye-injection method is used for visualization. It is observed that there exists a circulation of oil through the porous matrix and this flow contributes to the lubrication in the porous bearings. The flow pattern is dependent on the lubrication conditions. Under hydrodynamic lubrication conditions, the oil in the porous matrix flows away from the position of the load line towards the unloaded region. However under boundary lubrication conditions, when the oil feed pressure is negligibly small, most of the oil in the porous matrix flows toward the region where the oil film pressure would take the minimum.

A Study of the Mechanism of Lubrication in Porous Journal Bearings: Effects of Dimensionless Oil-Feed Pressure on Static Characteristics Under Hydrodynamic Lubrication Conditions

1994 ◽  
Vol 116 (3) ◽  
pp. 606-611 ◽  
Author(s):  
Satoru Kaneko ◽  
Yasuhiro Ohkawa ◽  
Yuji Hashimoto
Keyword(s):  
Hydrodynamic Lubrication ◽  
Hydrodynamic Pressure ◽  
Porous Matrix ◽  
Journal Bearings ◽  
Static Characteristics ◽  
Oil Film ◽  
Bearing Clearance ◽  
Feed Pressure ◽  
Angular Extent ◽  
Lubrication Conditions

The static characteristics of porous journal bearings under hydrodynamic lubrication conditions are theoretically investigated assuming that the oil is fed through their outside diameters under a small pressure. The angular extent of the oil film formed in the bearing clearance is numerically solved on the basis of the following postulate: when the oil film extent reaches steady state, the inflow of oil into the bearing clearance through the porous matrix due to the oil-feed pressure must make up for the oil leakage from the ends through the clearance gap and that into the porous matrix due to the hydrodynamic pressure in the film. Numerical results show that the dimensionless oil-feed pressure significantly influences the static characteristics. Experiments are also conducted for confirmation after the theoretical examination.

Polarized microbeam FT-IR analysis of single fibers

1996 ◽  
Vol 54 ◽  
pp. 206-207
Author(s):  
Liling Cho ◽  
David L. Wetzel
Keyword(s):  
Molecular Orientation ◽  
Transition Point ◽  
Polymer Fibers ◽  
Single Fiber ◽  
Wire Grid ◽  
Polyester Fibers ◽  
Ft Ir ◽  
Ir Analysis ◽  
The Relationship ◽  
Wire Grid Polarizer

Polarized infrared microscopy has been used for forensic purposes to differentiate among polymer fibers. Dichroism can be used to compare and discriminate between different polyester fibers, including those composed of polyethylene terephthalate that are frequently encountered during criminal casework. In the fiber manufacturering process, fibers are drawn to develop molecular orientation and crystallinity. Macromolecular chains are oriented with respect to the long axis of the fiber. It is desirable to determine the relationship between the molecular orientation and stretching properties. This is particularly useful on a single fiber basis. Polarized spectroscopic differences observed from a single fiber are proposed to reveal the extent of molecular orientation within that single fiber. In the work presented, we compared the dichroic ratio between unstretched and stretched polyester fibers, and the transition point between the two forms of the same fiber. These techniques were applied to different polyester fibers. A fiber stretching device was fabricated for use on the instrument (IRμs, Spectra-Tech) stage. Tension was applied with a micrometer screw until a “neck” was produced in the stretched fiber. Spectra were obtained from an area of 24×48 μm. A wire-grid polarizer was used between the source and the sample.

INTERACTION BETWEEN A FAMILY DOCTOR AND A DENTIST AT AN EARLY STAGE IN THE PREVENTION OF DISEASES OF THE GASTROINTESTINAL TRACT

2021 ◽  
Vol 2 (12(81)) ◽  
pp. 39-43
Author(s):  
M. Ibragimov ◽  
Y. Heydarova ◽  
A. Alizade ◽  
L. Ibragimova
Keyword(s):  
Gastrointestinal Tract ◽  
Oral Cavity ◽  
Early Stage ◽  
Family Doctor ◽  
Scientific Article ◽  
Oral Manifestations ◽  
Family Doctors ◽  
Long Period ◽  
Initial Stage ◽  
The Relationship

This scientific article discusses the oral manifestations of diseases of the gastrointestinal tract. This problem is relevant both for dentists and family doctors. In medicine, for a long period of time, the relationship between diseases affecting the gastrointestinal tract and their symptoms manifested in the oral cavity has been considered. Many scientists and physicians have dealt with this problem, their several opinions are presented in this article. There is a hypothesis among researchers that the oral cavity is a mirror in which all human diseases can be visible. In the oral cavity, most of the alterations occurring in the organism are manifested, due to which, with an attentive attitude to oral manifestations, the disease can be detected already at the initial stage.

Experimental study on the relationship between the friction coefficient and interference in locomotive axle press-fitting

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Ting Wang ◽  
Hanfei Guo ◽  
Jianjun Qiao ◽  
Xiaoxue Liu ◽  
Zhixin Fan
Keyword(s):  
Friction Coefficient ◽  
Coefficient Of Friction ◽  
Friction Pair ◽  
Rolling Stock ◽  
Content Type ◽  
Press Fitting ◽  
The Press ◽  
The Coefficient Of Friction ◽  
The Relationship ◽  
Locomotive Wheels

PurposeTo address the lack of data in this field and determine the relationship between the coefficient of friction and the interference between locomotive wheels and axles, this study evaluates the theoretical relationship between the coefficient of friction and the interference under elastic deformation.Design/methodology/approachWhen using numerical analyses to study the mechanical state of the contacting components of the wheels and axle, the interference between the axle parts and the coefficient of friction between the axle parts are two important influencing factors. Currently, as the range of the coefficient of friction between the wheel and axle in interference remains unknown, it is generally considered that the coefficient of friction is only related to the materials of the friction pair; the relationship between the interference and the coefficient of friction is often neglected.FindingsA total of 520 press-fitting experiments were conducted for 130 sets of wheels and axles of the HXD2 locomotive with 4 types of interferences, in order to obtain the relationship between the coefficient of friction between the locomotive wheel and axle and the amount of interference. These results are expected to serve as a reference for selecting the coefficient of friction when designing axle structures with the rolling stock, research on the press-fitting process and evaluations of the fatigue life.Originality/valueThe study provides a basis for the selection of friction coefficient and interference amount in the design of locomotive wheels and axles.

Prospects for Cooperation Between Russia and Syria in Various Scenarios of Military Conflict Development

2021 ◽  
pp. 50-55
Author(s):  
Alheder Haled
Keyword(s):  
Growth Rate ◽  
Inverse Correlation ◽  
Foreign Economic Policy ◽  
Military Conflict ◽  
Political Situation ◽  
Gdp Growth Rate ◽  
Initial Stage ◽  
Military Conflicts ◽  
The Military ◽  
The Relationship

The paper is devoted to determining the prospects for cooperation between Russia and the Syrian Arab Republic in various scenarios of military conflicts. In order to identify the relationship between the success of the country's foreign economic policy and the military conflicts waged on its territory, a study was conducted of such indicators of Syria as: the growth rate of the peace index and the GDP growth rate. A strong inverse correlation is revealed, which means that the level of political situation and peace in the state determines the efficiency of the economy. In view of this, various scenarios of the development of the military conflict in Syria have been studied: at the initial stage, at the stage of active hostilities, at the present stage of overcoming the crisis. The last stage involves four different scenarios for the development of a military conflict, including a local nature and a protracted nature with the involvement of other countries of the world. Options for developing cooperation between Russia and Syria have been identified for each scenario. Taking into account the assessment of the international political situation, the two most likely scenarios for further military events in Syria are identified, and the prospects for cooperation between Russia and Syria in these conditions are outlined.

Investigation of the causes of damage to freight cars during disbanding on non-mechanized sorting slides and development of measures to prevent them

2021 ◽  
pp. 4-13
Author(s):  
S. V. Tankeev ◽  
◽  
A. E. Kolodin ◽  
V. B. Sverdlov ◽  
A. V. Nazarov ◽  
...  
Keyword(s):  
Low Power ◽  
Coefficient Of Friction ◽  
Damage Assessment ◽  
Laboratory Tests ◽  
Rolling Stock ◽  
Third Body ◽  
Normative Documents ◽  
The Coefficient Of Friction ◽  
Loading And Unloading ◽  
The Relationship

The damage assessment of freight cars during shunting and loading and unloading operations was made. The need to review the normative documents regulating the relationship between the owners of rolling stock, owners of non-public tracks and the carrier is noted. The reasons for formation of damage on the wheel pairs of freight cars when disbanding on low-power sorting slides are considered. The conditions for ensuring the deceleration of detachments on non-mechanized sorting slides without damaging the wheels are determined. The analysis of methods for ensuring braking on low-power slides is carried out. A method was chosen to ensure the wheel set rotation by introducing a third body between the rubbing surfaces during the braking of cars, which will take over a part of the resulting heat flow, reducing the temperature and increasing the coefficient of friction in the «wheel-rail» contact zone. A method is proposed to provide braking on the non-mechanized sorting slide during shoe braking by applying a friction compound to a non-working rail. Laboratory tests were carried out, which showed that the introduction of a friction additive can achieve the necessary coefficient of friction to comply with the standard parameters of deceleration of the car in the braking zone.

scholarly journals Innovation and Entrepreneurship in a Space-time Framework Based on the Case of Poland

2019 ◽  
Vol 15 (2) ◽  
pp. 24-39
Author(s):  
Aleksandra Gaweł
Keyword(s):  
Research And Development ◽  
Explanatory Power ◽  
Regression Function ◽  
Regression Analyses ◽  
Initial Stage ◽  
Start Ups ◽  
The Relationship ◽  
Innovation Impact ◽  
Yearly Data ◽  
Innovation And Entrepreneurship

Although innovation and entrepreneurship have been subjects of researchers’ interests for years, nevertheless both the concepts and the relationships between them remain controversial. Since different indices are accepted for the measurement of these categories, the question is whether the relationship between them depends on the choice of measures. The aim of the paper is to indicate the innovation impact on the entrepreneurial process with regard to different measures of these concepts. The research was conducted with the use of regression analyses as a method and yearly data for Polish regions in the period 2003–2018. At the initial stage of the research as many measures of innovation and entrepreneurship as possible were introduced into the estimation of regression function parameters. Statistically insignificant variables were deleted at later stages of research. This research confirms that innovativeness and entrepreneurship are broad concepts and the relationship between them depends on the choice of measures. Saturation with enterprises and saturation with start-ups seem to be more sensitive to innovation than other measures of entrepreneurship. Innovation seen as input, measured by spending on research and development (R&D) has a bigger influence on entrepreneurship than the output innovation measured by revenues from innovative activities. Considering a relatively low level of explanatory power of innovations, it seems they are not the only factor influencing entrepreneurship.

scholarly journals The relationship between the effectiveness of performing technical elements and indicators of static and dynamic balance in young acrobats 6-7 years old

2021 ◽  
Vol 7 (4) ◽  
pp. 58-68
Author(s):  
T. Chernykh ◽  
V. Mulyk ◽  
K. Mulyk ◽  
А. Skaliy ◽  
А. Ostrowski ◽  
...  
Keyword(s):  
Correlation Coefficient ◽  
Dynamic Equilibrium ◽  
Dynamic Balance ◽  
Rank Correlation ◽  
Young Athletes ◽  
Spearman’S Rank Correlation ◽  
Spearman’S Rank Correlation Coefficient ◽  
Initial Stage ◽  
Equilibrium Test ◽  
The Relationship

Purpose: to determine the relationship between the performance of basic elements and indicators of static and dynamic balance in the training process of young acrobats 6-7 years. Material and methods. The study involved 16 young acrobats at the stage of initial training (age 6-7 years). All parents of the participants gave written consent for the participation of children in the study. The study involved testing the technique of performing basic elements of sports acrobatics and assessing the static and dynamic balance of young athletes. The relationship between (swallow, shoulder blade, forward squat, wheel (sideways overturning), bridges) and static and dynamic equilibrium tests was determined. Spearman's rank correlation coefficient method was used as a method of statistical analysis. Results. It is established that the largest relationship between the performance of basic elements and static balance in the basic exercises of young acrobats have: Romberg's test with the elements "Swallow", "Stand on the shoulders", "Bridge"; Biryuk test with elements "Swallow", "Wheel", "Bridge"; balance "Swallow" with elements "Swallow", "Wheel"; static equilibrium test with the elements "Swallow", "Rack on the shoulders", "Rolling forward with a squat", "Wheel". Reliable values ​​of the correlation coefficient were established between the tests of dynamic balance and the basic elements of sports acrobatics in young athletes 6-7 years, namely: "Swallow", "Flip forward with a squat", "Wheel" and "Bridge". The analysis of special tests of static and dynamic balance in mastering the basic elements of acrobatics at the first stage of long-term training makes it possible to use them to determine the level of coordination capabilities of young athletes and further improve the use of acrobatic exercises. Conclusions. A reliable relationship between the performance of basic exercises and indicators of static and dynamic balance in young acrobats at the initial stage of training. It is shown that the level of static and dynamic balance is of great importance for the assimilation and improvement of basic elements of technology by young acrobats 6-7 years. Static and dynamic balance tests can be used to individually build training programs and young acrobats. It is shown that sports acrobatics is a significant means of developing the balance of children 6-7 years.

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