scholarly journals A New Concept of the Mechanism of Variation of Tribological Properties of the Machine Elements Interacting Surfaces

2020 ◽  
Author(s):  
George Tumanishvili ◽  
Tengiz Nadiradze ◽  
Giorgi Tumanishvili
Keyword(s):  
Contact Zone ◽  
Tribological Properties ◽  
High Speed ◽  
Third Body ◽  
The Third ◽  
The Coefficient Of Friction ◽  
Speed Up ◽  
Machine Elements ◽  
Interacting Surfaces ◽  
Experimental Researches

The methods of estimation and prediction of tribological properties of the contact zone of interacting elements of machines are characterized by the low informativeness and accuracy that complicates provision of the proper tribological properties and hinders reliable and effective operation of machines. For obtaining more wide information about factors influencing tribological properties of the interacting surfaces, the experimental researches on the high speed (up to 70-m/s) and serial twin-disk machines were carried out. Our researches have shown that with different properties and degrees of destruction of the third body, the coefficient of friction can change up to 10 times or more, the wear rate up to 102-104 times, etc. This was the basis for a new concept of the mechanism of variation of tribological properties of interacting surfaces. The researches have shown a dependence of tribological properties of the contact zone on the properties and destruction degree of the third body that was assumed as a basis of new concept of the mechanism of variation of tribological properties of these surfaces. The monitoring of the third body destruction onset and development was carried out in the laboratory conditions and a criterion of the third body destruction was developed. The reasons of the negative, neutral and positive friction and mild, severe and catastrophic wear are shown.

The Effect of Machining Induced White Layer on Frictional and Wear Performance at Dry and Lubricated Sliding Contact

2009 ◽  
Author(s):  
R. A. Waikar ◽  
Y. B. Guo
Keyword(s):  
Wear Debris ◽  
White Layer ◽  
Solid Lubricants ◽  
Sliding Contact ◽  
Third Body ◽  
Machined Surface ◽  
Wear Performance ◽  
The Third ◽  
The Coefficient Of Friction ◽  
Dry Conditions

A white layer on a machined surface is often produced at abusive machining conditions. However, the effect of white layer on frictional and wear performance has received little attention. This study has shown that the existence of a turned white layer slightly decreases the coefficient of friction (COF), while a ground white layer significantly increases COF at dry conditions. At lubricated conditions, the turned white layer only slightly increases COF while the ground white layer slightly reduces it. The third body wear debris may act as solid lubricants leading to reduced friction.

The role of the third body in the fretting wear of 690 alloy

2020 ◽  
Vol 34 (09) ◽  
pp. 2050077
Author(s):  
Xue Mi ◽  
Xiao-Ming Bai ◽  
Pan Tang ◽  
Hai Xie ◽  
Jin-Fang Peng ◽  
...  
Keyword(s):  
Room Temperature ◽  
Normal Force ◽  
Fretting Wear ◽  
Wear Particles ◽  
Third Body ◽  
Experimental Conditions ◽  
The Third ◽  
The Coefficient Of Friction ◽  
Friction Energy

In this work, to investigate the role of the third body in the fretting behavior of 690 alloy, the fretting capabilities of 690 alloy against 405 stainless steel have been performed under various experimental conditions. The testing normal force and temperature varied from 10 N to 40 N and from room-temperature (RT) to [Formula: see text]C, respectively, at 5 Hz and 200 [Formula: see text]m. The results demonstrated that the profile shape of wear scar was dependent on the action of the wear particles. Three typical profile shapes were examined in this work: “U” shape, “W” shape and “M” shape. The balance of the formation and ejection of wear particles led to a steady value of the coefficient of friction (COF) and friction energy.

scholarly journals Three-stage question answering system with sentence ranking

10.29007/bj7w ◽  
2019 ◽  
Author(s):  
Daria Soboleva ◽  
Konstantin Vorontsov
Keyword(s):  
Neural Network ◽  
High Speed ◽  
Question Answering ◽  
Feature Space ◽  
Second Step ◽  
Question Answering System ◽  
The Third ◽  
Construction Techniques ◽  
Space Construction ◽  
Speed Up

We explore a recently proposed question answering system. We developed a high speed modification based on dividing the question answering system into three consecutive stages. The first step is to find the candidate documents that most likely contain the answer to the question. The second step is to rank sentences by the probability of having a correct answer to the question. The third step is to find the exact phrase that answers the question. At the third step we used a recently proposed recurrent bidirectional neural network predicting the beginning and the end of a response. In this paper we showed that the proposed question answering system allows to speed up its work without significant losses in the quality. For each step we also explored the feature space construction techniques allowing to improve the final quality.

Experimental identification and characterization of the effects of contaminants in the wheel—rail contact

2008 ◽  
Vol 222 (2) ◽  
pp. 207-216 ◽  
Author(s):  
S Descartes ◽  
C Desrayaud ◽  
Y Berthier
Keyword(s):  
High Speed ◽  
Negative Consequences ◽  
Energy Dispersive Analysis ◽  
Third Body ◽  
X Ray ◽  
The Third ◽  
Experimental Identification ◽  
Identification And Characterization ◽  
Scanning Electron

Previous results have highlighted the presence of a natural third body ranging in thickness from a few micrometres to several dozen micrometres on the rail and wheel. The third body layer, initially composed of particles stemming from the wheels and rails, flows into the contact to accommodate local sliding inside it. The work presented in this paper focuses on the identification of contaminants whose influence on the wheel—rail contact is significant. This influence can be considered as significant if it enters the contact, affects surface properties, modifies the third body layer, and possibly damages or protects the rail. The third body layer can progressively absorb and assimilate solid (ballast stone, sand) and fluid (oil) contaminants existing on rails, and thus reduce their negative consequences on rail lifetime. These phenomena are the result of the exchange of third body flows between the wheel and rail. A high-speed camera was used for this experimental study performed on a real site. The analyses of the dynamic images are coupled with tribological analyses of the surfaces by scanning electron microscopy and X-ray energy dispersive analysis.

Effect of Graphite Content on the Tribological Performance of Copper-Matrix Composites Under Different Friction Speeds

2017 ◽  
Vol 139 (4) ◽  
Author(s):  
Han Xiao-Ming ◽  
Gao Fei ◽  
Su Lin-Lin ◽  
Fu Rong ◽  
Zhang En
Keyword(s):  
Friction Coefficient ◽  
Wear Rate ◽  
High Speed ◽  
Copper Matrix ◽  
Tribological Performance ◽  
Matrix Composites ◽  
Third Body ◽  
H13 Steel ◽  
Copper Matrix Composites ◽  
The Third

The effect of graphite (Gr) content on tribological performance of copper-matrix composites against H13 steel was investigated using a pin-on-disk test in the range of 3.14–47.1 m/s. The composites with different weight fractions of Gr (up to 18%) were fabricated by powder metallurgy technique. The results showed that the friction coefficient and wear rate generally decreased with the increase in Gr content. However, the friction coefficient and wear rate differ at various speeds. At 200 and 500 r/min, the friction coefficient and wear rate kept lower with the increase in Gr content, because the third body of Cu–Al–3%Gr specimen had strong fluidity and plasticity. By contrast, the particle third body of Cu–Al–12%Gr specimen, which contained higher content of Gr, could roll easily. Increased Gr feeding to the third body was reasonable for the decreasing of friction coefficient and wear with the increasing of the amount of Gr content at the speed in the range of 1000–2000 r/min. Under the high-speed, the friction coefficient showed slight change because the friction temperature induced all the third bodies to extend and flow effortlessly without componential influence. However, wear decreased significantly because the third body possessed more metal, which favored attachment to the counter disk.

Scanning x-ray fluorescence microscopy and principal component analysis

1992 ◽  
Vol 50 (2) ◽  
pp. 1752-1753
Author(s):  
Brian Cross
Keyword(s):  
Principal Component Analysis ◽  
Fluorescence Microscopy ◽  
Spatial Resolution ◽  
High Speed ◽  
Image Acquisition ◽  
Principal Component ◽  
Fluorescence Microscope ◽  
Acquisition Rate ◽  
X Ray ◽  
Speed Up

A relatively new entry, in the field of microscopy, is the Scanning X-Ray Fluorescence Microscope (SXRFM). Using this type of instrument (e.g. Kevex Omicron X-ray Microprobe), one can obtain multiple elemental x-ray images, from the analysis of materials which show heterogeneity. The SXRFM obtains images by collimating an x-ray beam (e.g. 100 μm diameter), and then scanning the sample with a high-speed x-y stage. To speed up the image acquisition, data is acquired "on-the-fly" by slew-scanning the stage along the x-axis, like a TV or SEM scan. To reduce the overhead from "fly-back," the images can be acquired by bi-directional scanning of the x-axis. This results in very little overhead with the re-positioning of the sample stage. The image acquisition rate is dominated by the x-ray acquisition rate. Therefore, the total x-ray image acquisition rate, using the SXRFM, is very comparable to an SEM. Although the x-ray spatial resolution of the SXRFM is worse than an SEM (say 100 vs. 2 μm), there are several other advantages.

Reosquido Desalinasi Metode Evaporasi dengan Ultraviolet Berbasis Mikrokontroller

2018 ◽  
Vol 3 (2) ◽  
pp. 38-47
Author(s):  
Muhammad Abdul Azis ◽  
Nuryake Fajaryati
Keyword(s):  
Temperature Measurement ◽  
Fresh Water ◽  
Sea Water ◽  
Evaporation Process ◽  
Heater Element ◽  
The Third ◽  
Turn On ◽  
Speed Up ◽  
Arduino Uno

This research aims to create a Reosquido desalination tool for evaporation methods using a microcontroller. This tool can control the temperature to speed up the evaporation process in producing fresh water. The method applied to Reosquido desalination uses Evaporation. The first process before evaporation is the detection of temperature in sea water that will be heated using an element heater. The second process of temperature measurement is to turn off and turn on the Arduino Uno controlled heater, when the temperature is less than 80 ° then the heater is on. The third process is evaporation during temperatures between 80 ° to 100 °, evaporation water sticks to the glass roof which is designed by pyramid. Evaporated water that flows into the reservoir is detected by its solubility TDS value. The fourth process is heater off when the temperature is more than 100 °. Based on the results of the testing, the desalination process using a microcontroller controlled heater can speed up the time up to 55% of the previous desalination process tool, namely manual desalination prsoes without using the heater element controlled by the temperature and controlled by a microcontroller which takes 9 hours. Produces fresh water as much as 30ml from 3000ml of sea water, so that it can be compared to 1: 100.

scholarly journals Extended analytical formulae for the perturbed Keplerian motion under low-thrust acceleration and orbital perturbations

2021 ◽  
Vol 133 (3) ◽  
Author(s):  
Marilena Di Carlo ◽  
Simão da Graça Marto ◽  
Massimiliano Vasile
Keyword(s):  
Gravitational Perturbation ◽  
Low Thrust ◽  
Orbital Elements ◽  
Third Body ◽  
The Third ◽  
Orbital Perturbations ◽  
Analytical Formulae ◽  
Numerical Orbit ◽  
Body Potential

AbstractThis paper presents a collection of analytical formulae that can be used in the long-term propagation of the motion of a spacecraft subject to low-thrust acceleration and orbital perturbations. The paper considers accelerations due to: a low-thrust profile following an inverse square law, gravity perturbations due to the central body gravity field and the third-body gravitational perturbation. The analytical formulae are expressed in terms of non-singular equinoctial elements. The formulae for the third-body gravitational perturbation have been obtained starting from equations for the third-body potential already available in the literature. However, the final analytical formulae for the variation of the equinoctial orbital elements are a novel derivation. The results are validated, for different orbital regimes, using high-precision numerical orbit propagators.

Expansion of the third-body disturbing function

1980 ◽  
Author(s):  
R. BROUCKE
Keyword(s):  
Disturbing Function ◽  
Third Body ◽  
The Third

scholarly journals Impact of Operating Time on Selected Tribological Properties of the Friction Material in the Brake Pads of Passenger Cars

Materials ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 884
Author(s):  
Andrzej Borawski
Keyword(s):  
Tribological Properties ◽  
Operating Time ◽  
Friction Material ◽  
Operating Conditions ◽  
Direct Impact ◽  
Passenger Cars ◽  
Wear Factor ◽  
Brake Pads ◽  
Road Users ◽  
The Coefficient Of Friction

Braking systems have a direct impact on the safety of road users. That is why it is crucial that the performance of brakes be dependable and faultless. Unfortunately, the operating conditions of brakes during their operating time are affected by many variables, which results in changes in their tribological properties. This article presents an attempt to develop a methodology for studying how the operating time affects the value of the coefficient of friction and the abrasive wear factor. The Taguchi method of process optimization was used to plan the experiment, which was based on tests using the ball-cratering method. The results clearly show that the degree of wear affects the properties of the friction material used in the production process of brakes.

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