scholarly journals Specific Problems in Measurement of Coefficient of Friction Using Variable Incidence Tribometer

Symmetry ◽  
2020 ◽  
Vol 12 (8) ◽  
pp. 1235
Author(s):  
Tatiana Kelemenová ◽  
Miroslav Dovica ◽  
Pavol Božek ◽  
Ivana Koláriková ◽  
Ondrej Benedik ◽  
...  
Keyword(s):  
Coefficient Of Friction ◽  
Relative Motion ◽  
Sliding Friction ◽  
Input Parameter ◽  
Motion Velocity ◽  
Input Quantity ◽  
Science Topic ◽  
The Subject ◽  
Main Input ◽  
Static Coefficient Of Friction

The subject of this paper is the solution to specific problems in the measurement of the coefficient of the sliding friction of material pairs using a variable incidence tribometer. The aim of this work was to solve the questions of the measurement of the static coefficient of friction using a variable incidence tribometer from the perspective of metrology. In particular, we intended to research the expression of the credibility of this measurement and the possibility of increasing the credibility of the measurement. Another problem that needs to be solved is the method of carrying out the measurement, which has an impact on its achieved uncertainty. Sliding friction is a phenomenon that depends on many material properties such as contact area roughness, moisture, lubricants, temperature, and relative motion velocity. If environmental conditions are defined, the main input parameter is the relative motion velocity. For this input quantity, friction force becomes a symmetrical problem, and it is only necessary to explore this phenomenon for positive values of velocities. Symmetry in this area simplifies the research of this science topic.

A Generalized Traction Curve for EHL Contacts

2000 ◽  
Vol 123 (2) ◽  
pp. 248-253 ◽  
Author(s):  
B. Jacod ◽  
C. H. Venner ◽  
P. M. Lugt
Keyword(s):  
Coefficient Of Friction ◽  
Sliding Friction ◽  
Operating Conditions ◽  
Wide Range ◽  
The Coefficient Of Friction ◽  
Friction Curve ◽  
The Subject ◽  
Friction Prediction ◽  
Elliptic Contact ◽  
Theoretical Results

In this paper the subject of friction prediction is revisited, with the aim of obtaining a general formula predicting the coefficient of friction over a wide range of operating conditions. By means of full numerical simulations of the smooth isothermal elliptic contact, and assuming an Eyring non-Newtonian behavior, the coefficient of friction is computed for a wide range of operating conditions. It is shown that with respect to sliding friction, all results can be presented on a single generalized friction curve relating a reduced coefficient of friction to a characteristic nondimensional shear stress. Finally, it is shown that some measured data presented in the literature when presented in terms of the derived parameters closely follow the derived behavior, which provides a validation of the theoretical results.

scholarly journals Integration Biases in the Ouchi and other Visual Illusions

Perception ◽  
10.1068/p2983 ◽  
2000 ◽  
Vol 29 (6) ◽  
pp. 721-727 ◽  
Author(s):  
George Mather
Keyword(s):  
Relative Motion ◽  
Experimental Test ◽  
Empirical Studies ◽  
Visual Illusions ◽  
Local Motion ◽  
Bayesian Approaches ◽  
Visual Coding ◽  
Texture Pattern ◽  
The Subject ◽  
The Way

A texture pattern devised by the Japanese artist H Ouchi has attracted wide attention because of the striking appearance of relative motion it evokes. The illusion has been the subject of several recent empirical studies. A new account is presented, along with a simple experimental test, that attributes the illusion to a bias in the way that local motion signals generated at different locations on each element are combined to code element motion. The account is generalised to two spatial illusions, the Judd illusion and the Zöllner illusion (previously considered unrelated to the Ouchi illusion). The notion of integration bias is consistent with recent Bayesian approaches to visual coding, according to which the weight attached to each signal reflects its reliability and likelihood.

scholarly journals DETERMINING THE COEFFICIENT OF FRICTION OF WOOD-BASED MATERALS FOR FURNITURE PANELS IN THE ASPECT OF MODELLING THEIR SHREDDING PROCESS

Wood Research ◽  
2021 ◽  
Vol 66 (5) ◽  
pp. 789-805
Author(s):  
MATEUSZ KUKLA ◽  
ŁUKASZ WARGUŁA ◽  
ALEKSANDRA BISZCZANIK
Keyword(s):  
Coefficient Of Friction ◽  
Kinetic Coefficient ◽  
Drive Unit ◽  
Base Surface ◽  
The Coefficient Of Friction ◽  
Kinematic Coefficient ◽  
Cutting Processes ◽  
Static Coefficient Of Friction ◽  
Static Coefficient ◽  
Selection Of

In order to improve the power selection of the drive unit for the shredding machines,theauthors determine the values of friction coefficients used in the cutting force models. These values consider the friction between steel and such wood-based materials as chipboard, MDF and OSB. The tests concern laminated and non-laminated external surfaces and surfaces subjected to cutting processes. The value of the coefficient of friction for the tested materials is in the range: for the static coefficient of friction 0.77-0.33, and for the kinetic coefficient of friction 0.68-0.25. The highest values of the static and kinematic coefficient of friction were recorded for MDF (non-laminated external surface) and they were equal respectively: 0.77 and 0.68. In turn, thesmallest values of the discussed coefficients were recorded for chipboard (laminated external wood-base surface), which were at the level of 0.33 and 0.25, resp.

scholarly journals Solid Lubrication by Multiwalled Carbon Nanotubes in Air and in Vacuum for Space and Aeronautics Applications

2005 ◽  
Author(s):  
K. Miyoshi ◽  
K. W. Street ◽  
R. L. Vander Wal ◽  
R. Andrews ◽  
David Jacques ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Multiwalled Carbon Nanotubes ◽  
Coefficient Of Friction ◽  
Sliding Friction ◽  
Solid Lubrication ◽  
Multiwalled Carbon ◽  
Solid Lubrication Friction ◽  
The Coefficient Of Friction ◽  
Dry Conditions ◽  
Steel Balls

To evaluate recently developed aligned multiwalled carbon nanotubes (MWNTs) and dispersed MWNTs for solid lubrication applications, unidirectional sliding friction experiments were conducted with 440C stainless steel balls and hemispherical alumina-yttria stabilized zirconia pins in sliding contact with the MWNTs deposited on quartz disks in air and in vacuum. The results indicate that MWNTs have superior solid lubrication friction properties and endurance lives in air and vacuum under dry conditions. The coefficient of friction of the dispersed MWNTs is close to 0.05 and 0.009 in air and in vacuum, respectively, showing good dry lubricating ability. The wear life of MWNTs exceeds 1 million passes in both air and vacuum showing good durability. In general, the low coefficient of friction can be attributed to the combination of the transferred, agglomerated patches of MWNTs on the counterpart ball or pin surfaces and the presence of tubular MWNTs at interfaces.

scholarly journals System parameterization of the budget model of investment construction project

2021 ◽  
pp. 69-81
Author(s):  
Sergei Vladimirovch Gorbunov ◽  
Marina Yurievna Mishlanova ◽  
Dmitrii Valer'evich Khavin
Keyword(s):  
Construction Projects ◽  
Input Parameter ◽  
Managerial Accounting ◽  
Managerial Decision ◽  
Universal System ◽  
Subject Field ◽  
Budget Model ◽  
The Subject ◽  
Low Efficiency ◽  
System Variables

This article reviews the definitions of budgeting and budget model, their role in cost management of investment construction projects, and the subject field of budget modeling of a project. The author indicates the relevance of implementation of budgeting in management of investment construction projects, as well as the factors of low efficiency of this process. The subject of this research is the system variables of the budget model: functions, content, structure, levels, quantitative and qualitative indicators, standards, methodological and analytical parameters, and financial modeling processes. The peculiarity of the subject of research lies in systematicity, need for consolidation of budgets in various aspects, and compatibility of the local budget models for creating a reasonably universal system for supporting managerial decision-making. Description is given to the basic methodological provisions of the development of budget models of investment construction projects. This article is first to elaborate on the analytical parameters of budget modeling of investment construction projects, as well indicate various parametric levels in reference to each other. The author develops the financial planning processes and the pattern of project budgeting, as well as adapts the cybernetic principles of “input – output”. It is suggested to use a special accounting scheme in the budget model of the project, which is based on the managerial accounting policy approved by the subject. For achieving compatibility of the methods of financial administration, the author offers to coordinate the cost pool in estimates and budgets, maximal expenditure accounting, reduce scheduling uncertainty, and consider dynamic factors. The budget model is viewed as an input parameter of cost control over the investment construction projects. The vectors of further improvement of budgeting of investment construction projects are proposed.

scholarly journals Multi-configuration Stiffened Panels under Compressive Load: Part 1 – Theoretical Analysis

2018 ◽  
Vol 7 (3.11) ◽  
pp. 38
Author(s):  
Ramzyzan Ramly ◽  
Wahyu Kuntjoro ◽  
Amir Radzi Abdul Ghani ◽  
Rizal Effendy Mohd Nasir ◽  
Zulkifli Muhammad
Keyword(s):  
Theoretical Analysis ◽  
Experimental Analysis ◽  
Critical Loads ◽  
Input Parameter ◽  
Compressive Loading ◽  
Compressive Load ◽  
Cross Sectional ◽  
Stiffened Panels ◽  
Compression Load ◽  
Main Input

Stiffened panels are the structure used in the aircraft wing skin panels. Stiffened panels are often critical in compression load due to its thin structural configuration. This paper analyzes the critical loads of a multi configuration stiffened panels under axial compressive loading. The study comprised three main sections; theoretical analysis, numerical analysis and experimental analysis. The present paper deals only with the theoretical analysis. This first part of analysis is very important since the results will be the main input parameter for the subsequent numerical and experimental analysis. The analysis was done on the buckling properties of the panels. Four panel configurations were investigated. Results showed that even though the stiffened panels have the same cross-sectional area, their critical loads were not identical.   

Influence of Third Element of TiNi Alloy on Tribological Behavior in Dry and Wet Conditions for Orthodontic Applications

2019 ◽  
Vol 803 ◽  
pp. 167-171
Author(s):  
Aphinan Phukaoluan ◽  
Anak Khantachawana ◽  
Pongpan Kaewtatip ◽  
Surachai Dechkunakorn
Keyword(s):  
Surface Roughness ◽  
Surface Area ◽  
Coefficient Of Friction ◽  
Sliding Friction ◽  
Tribological Behavior ◽  
Artificial Saliva ◽  
Tini Alloy ◽  
Oral Temperature ◽  
Wet Condition ◽  
Dry And Wet Conditions

The tribological behavior of Ti49.4Ni50.6, Ti49Ni46Cu5 and Ti50Ni47Co3 (at%) alloy in dry and wet conditions was studied. The alloy was prepared in a Vacuum Arc Re-melting (VAR), homogenized at 800°C for 3600 s and quenched in water. The phase transformation temperatures were measured by differential scanning calorimetry. Before a tribology test, it is necessary to determine surface roughness, because high surface roughness affects friction. The hardness behavior, based on the load over residual indent area, was determined by a Vickers hardness tester. The sliding friction tests were performed using a ball-on-disk tribometer in dry condition at room temperature and wet condition in artificial saliva (pH 5.35) at 37°C (Oral temperature). The results showed that transformation temperature (Af) lowered oral temperature (37°C), this was mainly attributed to the superelastic properties that can be taken into orthodontic applications. The studies showed significant influences in dry condition of coefficient of friction. Caused by the force between the ball and the disk, contact pressure of surface area effect in wear occurred. The debris could not be removed from the surface area tested. TiNiCu and TiNiCo generated significantly lower average coefficient of friction when tested under dry condition, which may have been due to the addition of Cu and Co. Wet condition decreased coefficient of friction more than dry condition, owing to the lubricating effects of artificial saliva.

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