scholarly journals Influence of Sliding Speed on Boundary Lubrication

1963 ◽  
Vol 29 (199) ◽  
pp. 563-572
Author(s):  
Yukio MIYAKAWA
Keyword(s):  
Boundary Lubrication ◽  
Sliding Speed

Experimental and Modeling Studies for Understanding Shoe-Floor-Contaminant Friction and Designing for Slip-Resistance

2012 ◽  
Author(s):  
Kurt Beschorner
Keyword(s):  
Experimental Data ◽  
Finite Element ◽  
Boundary Lubrication ◽  
Viscous Fluids ◽  
Finite Element Models ◽  
Sliding Speed ◽  
Friction Coefficients ◽  
Real Area Of Contact ◽  
Lubrication Regime ◽  
Real Area

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.

scholarly journals Parametric identification of the mathematical model of the functioning of tribosystems in the conditions of boundary lubrication

2021 ◽  
Vol 101 (3) ◽  
pp. 6-14
Author(s):  
A. Voitov ◽  
Keyword(s):  
Quality Factor ◽  
Time Constant ◽  
Boundary Lubrication ◽  
Rapid Change ◽  
Parametric Identification ◽  
Surface Layers ◽  
Sliding Speed ◽  
External Conditions ◽  
Time Required ◽  
Friction Surfaces

The parametric identification of the tribosystem as an object of modeling the functioning of tribosystems in the conditions of boundary lubrication is performed in the work. Using the analysis of the dimensions of significant factors, expressions are obtained to calculate the gain and time constants. It is established that the coefficient takes into account the degree of influence of the load, sliding speed, tribological characteristics of the lubricating medium on the quality factor of the tribosystem. It is shown that the increase in the coefficient will have a positive effect on the processes inherent in tribosystems during operation. Coefficient – characterizes the magnitude of the change in volumetric wear rate and friction coefficient when changing the magnitude of the load, sliding speed, quality factor of the tribosystem. Coefficient – characterizes the ability of the tribosystem to self-organize when changing the values of the input parameters by rearranging the surface layers of materials from which the triboelements are made during secondary running-in. It is shown that the value of the coefficient is large will contribute to the rapid change in the roughness of the friction surfaces, the restructuring of the structure of the surface layers, the appearance of oxidizing films on the friction surfaces (secondary structures). It is proved that the time constant – this is the time required to change the roughness of the friction surfaces and rearrange the structure of the materials of the surface layers when changing external conditions. Time constant characterizes the time during which there is a stabilization of the temperature gradient by volume of triboelements, taking into account the thermal conductivity of materials when changing external conditions. Time constant characterizes the time during which the tribosystem returns to a steady state of operation after the cessation of the outrageous force, or the time to stabilize the parameters in the new mode of operation. It is proved that the value will be optimal for the process of self-organization. It is shown that one of the factors that can control the value , this is the sliding speed

Using a 3-Dimensional Viscoelastic Finite Element Model to Analyze the Effects of Floor Roughness, Sliding Speed and Material Properties on Shoe-Floor Friction

2012 ◽  
Author(s):  
Gurjeet Singh ◽  
Vikas Hasija ◽  
Pradeep L. Menezes ◽  
Kurt Beschorner
Keyword(s):  
Numerical Simulations ◽  
Material Property ◽  
Boundary Lubrication ◽  
Material Properties ◽  
Experimental Studies ◽  
Health Concern ◽  
Contributing Factors ◽  
Sliding Speed ◽  
Hysteresis Friction ◽  
Adhesion Friction

Slip and fall accidents are a major occupational health concern. Important factors affecting shoe-floor friction is critical to identifying and resolving unsafe surfaces and designing. Experimental studies have indicated that several factors including floor roughness, sliding speed and shoe materials affect shoe-floor friction although the precise nature of the mechanism behind this phenomenon is not well understood. In addition, recent studies have suggested that boundary lubrication is highly relevant to slipping and that adhesion and hysteresis are the main contributing factors to boundary lubrication. The purpose of this study is to perform the numerical simulations to analyze the effects of floor roughness (asperity height), sliding speed and material properties on ratio of real area of contact and normal force (relevant to adhesion friction) and hysteresis friction for a viscoelastic shoe material interacting with a hard floor surface. A 3D shoe model and 3D vinyl floor model was simulated with speed 0.01 m/s, 0.5 m/s, 0.75 m/s and 1 m/s in three different floor surfaces. The material property was also varied in the numerical simulations. The study showed that roughness affects both the hysteresis and adhesion friction whereas sliding speed and material property affects the adhesion friction only. The dependence of adhesion and hysteresis friction on roughness, sliding speed and material property is useful in understanding the shoe-floor friction phenomenon and development of slip resistant sports and work shoes.

scholarly journals Influence of Sliding Speed on Boundary Lubrication

1963 ◽  
Vol 6 (24) ◽  
pp. 833-839
Author(s):  
Yukio MIYAKAWA
Keyword(s):  
Boundary Lubrication ◽  
Sliding Speed

New Bench Test to Study Mild Lubricated Wear

2005 ◽  
Author(s):  
J. Y. Fan ◽  
Hugh A. Spikes
Keyword(s):  
Boundary Lubrication ◽  
Bench Test ◽  
Sliding Speed ◽  
Mild Wear ◽  
Lubrication Conditions

This extended abstract describes a new bench test for measuring and studying mild, lubricated wear. The method combines MTM, which is able to produce contra-rotation so as to obtain high sliding speed while retaining low entrainment speed and thus boundary lubrication conditions, with ICP which is employed to analyze trace levels of iron in lubricants so as to monitor mild wear throughout a test.

The Influence of Lubricants on Static Friction Characteristics Under Boundary Lubrication

1985 ◽  
Vol 107 (2) ◽  
pp. 188-194 ◽  
Author(s):  
S. Kato ◽  
E. Marui ◽  
A. Kobayashi ◽  
S. Senda
Keyword(s):  
Machine Tool ◽  
Surface Topography ◽  
Contact Pressure ◽  
Boundary Lubrication ◽  
Carrying Capacity ◽  
Static Friction ◽  
Load Carrying Capacity ◽  
Sliding Speed ◽  
Friction Characteristics ◽  
Load Carrying

Based on a new boundary lubrication model, the characteristics of lubricants under boundary lubrication at low sliding speed and low contact pressure such as in machine tool slideways are investigated in relation to surface topography. It is clarified theoretically and ascertained experimentally that the property of lubricants under boundary lubrication can be estimated by the newly defined appraisal coefficient of boundary lubrication property determined by the thickness and load carrying capacity of adsorbed lubricant film and the surface topography.

scholarly journals Structural identification of the mathematical model of the functioning of tribosystems under conditions of boundary lubrication

2021 ◽  
Vol 100 (2) ◽  
pp. 26-33
Author(s):  
A. Voitov
Keyword(s):  
Differential Equation ◽  
Quality Factor ◽  
Boundary Lubrication ◽  
Input Signal ◽  
Methodological Approach ◽  
Structural Identification ◽  
Material Structure ◽  
Sliding Speed ◽  
Time Constants ◽  
Operating Modes

In the work, a methodological approach to obtaining mathematical models was further developed, which describe the functioning of tribosystems in stationary and transient modes under boundary lubrication conditions.The structural identification of the tribosystem as an object of modeling the functioning of tribosystems in the conditions of boundary lubrication is performed. It is established that the operation of tribosystems is described by a third-order differential equation and, in contrast to the known ones, takes into account the function of changing the quality factor of the tribosystem during running-in. It is shown that the nature of the functioning of tribosystems under conditions of ultimate lubrication depends on the gain and time constants included in the differential equation. It is shown that the coefficient К1 takes into account the degree of influence of the input signal (load, sliding speed, tribological characteristics of the lubricating medium), on the value of the output signal (quality factor of the tribosystem). Coefficient К2 takes into account the magnitude of the change of the output parameters (volumetric wear rate and friction coefficient) when changing the values of the input parameters (load, sliding speed, quality factor of the tribosystem. Coefficient К3 takes into account the degree of influence of the input signal on the restructuring of the material structure in the surface layers of the triboelements.The time constants of the tribosystem characterize the inertia of the processes occurring in the tribosystem, during running-in, or during changes in operating modes. Increasing the time constants makes the process less susceptible to changes in the input signal, the running-in process increases over time, and the tribosystem becomes insensitive to small changes in load and slip speed. Conversely, the reduction of time constants makes the tribosystem sensitive to any external changes.

Boundary Lubrication Model under Square Surface Contact Condition

2010 ◽  
Vol 29-32 ◽  
pp. 1396-1401
Author(s):  
Wei Zu Wang ◽  
Liu Yi Wang ◽  
Zeng Xue Zhang ◽  
Hai Bo Chen
Keyword(s):  
Friction Coefficient ◽  
Boundary Lubrication ◽  
Contact Area ◽  
Normal Load ◽  
Contact Temperature ◽  
Sliding Speed ◽  
Surface Contact ◽  
Relative Deficiency ◽  
Frictional Surfaces ◽  
Relationship Of

The contact temperature of the frictional surfaces under boundary lubrication in square surface contact is calculated according to classic heat conduction theories. The friction coefficient of boundary lubrication is expressed with the friction coefficient of boundary film and direct contact. Then, a model is developed based on the relationship of adsorption heat, friction coefficient and contact temperature. The model is used to solve a sample question. The results illuminate that when the applied load is relatively small, the friction coefficient keeps at a stable small value with the variation of the sliding speed and the load. However, when the load reaches a certain value, the increase of the sliding speed or the normal load both leads to the increase of the friction coefficient. The friction coefficient is also increases with the increase of the contact temperature. The relative deficiency of oil, which indicates the proportion of the true contact area to mean contact area, has almost the same variation trend of the friction coefficient.

The Effect of Aging and Sliding Speed on Wear Behaviour of Cu-Cr-Zr Alloy

2013 ◽  
Vol 55 (6) ◽  
pp. 468-471 ◽  
Author(s):  
Dursun Özyürek ◽  
Ibrahim Ciftci ◽  
Tansel Tuncay
Keyword(s):  
Wear Behaviour ◽  
Sliding Speed ◽  
Zr Alloy
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