Calculation of Average Coefficient of Friction During Braking

It is shown that the maximum torque of adaptive friction clutches of the second generation (baseline) when it is configured with the minimum coefficient of friction less than the setting based on an average coefficient of friction, if a ratio of the coefficient of friction to its minimum value more than the value of the safety factor.

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Tribological Characterization of AZ91 and AE42 Magnesium Alloys in Fretting Contact

Journal of Tribology ◽

10.1115/1.4036922 ◽

2017 ◽

Vol 140 (1) ◽

Cited By ~ 1

Author(s):

D. Khabale ◽

M. F. Wani

Keyword(s):

Magnesium Alloys ◽

Coefficient Of Friction ◽

Normal Load ◽

Fretting Wear ◽

Wear Volume ◽

Dry Sliding ◽

Running Time ◽

Average Coefficient ◽

Tribological Characterization

Fretting wear studies were conducted on AZ91 and AE42 magnesium alloys against steel ball. Average coefficient of friction (COF) remains steady with the increase in running time. However, average coefficient of friction decreases with the increase in normal load and frequency and marginally increases with the increase in amplitude. A constant average coefficient of friction of 0.06 was observed for both AZ91 and AE42 under dry sliding conditions at normal load of 50 N. Wear volume increases linearly with increasing running time. Wear volume first decreases sharply, attains minima, and then increases marginally with the increase in normal load. However, wear volume increases with increasing amplitude and frequency. Higher specific wear rate of 10.5 × 10−6 mm3 N−1·m−1 was observed for AE42, as compared to 4.5 × 10−6 mm3 N−1·m−1 for AZ91. The wear in magnesium alloy was caused by a combination of adhesion, abrasion, oxidation, delamination, and plastic deformation under different fretting conditions.

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Plowing Friction Under Harmonic Normal Loads

Journal of Tribology ◽

10.1115/1.2833932 ◽

1999 ◽

Vol 121 (2) ◽

pp. 282-285 ◽

Cited By ~ 2

Author(s):

D. P. Hess

Keyword(s):

Shear Strength ◽

Coefficient Of Friction ◽

Metal Surfaces ◽

Sliding Friction ◽

Normal Load ◽

Hard Materials ◽

Lubricated Contacts ◽

Highly Nonlinear ◽

Average Coefficient ◽

The Coefficient Of Friction

The influence of harmonic normal loads on sliding friction is investigated through analysis of contacts consisting of conical and spherical sliders of hard materials on softer metal surfaces. Friction for such contacts is assumed to result from a plowing component and a shearing component. Calculations and experiments show that the coefficient of friction is essentially independent of normal load for contacts with conical sliders. However, for spherical sliders the relation between the coefficient of friction and normal load is highly nonlinear. In the presence of harmonic variations in normal load, this non-linearity causes a shift in the average coefficient of friction. For ideal lubricated contacts, the shearing component of friction is very small and for this case, it is shown that the maximum average reduction in the coefficient of friction is ten percent. When the shearing component is more significant, as with dry contacts, the shift is less. For example, when the shear strength is one-sixth the hardness of the softer material, the maximum average reduction in the coefficient of friction is five percent.

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Wear Behavior of a Heat-Treatable Al-3.5Cu-1.5 Mg-1Si Alloy Manufactured by Selective Laser Melting

Materials ◽

10.3390/ma14227048 ◽

2021 ◽

Vol 14 (22) ◽

pp. 7048

Author(s):

Pei Wang ◽

Yang Lei ◽

Jun-Fang Qi ◽

Si-Jie Yu ◽

Rossitza Setchi ◽

...

Keyword(s):

Wear Rate ◽

Selective Laser Melting ◽

Coefficient Of Friction ◽

Mechanical Performance ◽

Wear Behavior ◽

Secondary Phase ◽

Specific Wear Rate ◽

Laser Melting ◽

Heat Treated ◽

Average Coefficient

In this study, the wear behavior of a heat-treatable Al-7Si-0.5Mg-0.5Cu alloy fabricated by selective laser melting was investigated systematically. Compared with the commercial homogenized AA2024 alloy, the fine secondary phase of the SLM Al-Cu-Mg-Si alloy leads to a low specific wear rate (1.8 ± 0.11 × 10−4 mm3(Nm)−1) and a low average coefficient of friction (0.40 ± 0.01). After the T6 heat treatment, the SLM Al-Cu-Mg-Si alloy exhibits a lower specific wear rate (1.48 ± 0.02 × 10−4 mm3(Nm)−1), but a similar average coefficient of friction (0.34 ± 0.01) as the heat-treated AA2024 alloy. Altogether, the SLM Al-3.5Cu-1.5 Mg-1Si alloy is suitable for the achievement of not only superior mechanical performance, but also improved tribological properties.

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Effect of Pad Surface Texture and Slurry Abrasive Concentration on Tribological and Kinetic Attributes of ILD CMP

MRS Proceedings ◽

10.1557/proc-767-f2.8 ◽

2003 ◽

Vol 767 ◽

Cited By ~ 5

Author(s):

Ara Philipossian ◽

Scott Olsen

Keyword(s):

Coefficient Of Friction ◽

Surface Texture ◽

Material Removal ◽

Hydrodynamic Lubrication ◽

Removal Rate ◽

Two Phase ◽

Lubrication Regimes ◽

Time Coefficient ◽

Wide Range ◽

Average Coefficient

AbstractReal-time coefficient of friction (COF) analysis is used to determine the extent of normal and shear forces during CMP and identify the lubrication regimes associated with the process. Pads with different surface textures and slurries with varying abrasive concentrations are used to polish ILD films over a wide range of operating parameters. Results show that by varying abrasive concentration and pad surface texture, one can cause the process tribology to change from ‘boundary lubrication’ to ‘partial lubrication’, to ‘hydrodynamic lubrication’. A two-phase model relating average coefficient of friction and Preston's constant is presented. At abrasive concentrations up to 9 percent, material removal is proportional to the extent of contact between the abrasives and the wafer. At abrasive concentrations between 9 to 25 percent, removal rate is directly influenced by average COF. A new parameter termed the ‘tribological mechanism indicator’ is defined and extracted from the data, which coupled with the information on COF and ILD removal rate, results in a series of ‘universal’ correlations. A qualitative model based on pad storage modulus is used to explain the trends.

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Modeling and Optimization of Friction and Wear Characteristics of Ti3Al2.5V Alloy Under Dry Sliding Condition

Journal of Tribology ◽

10.1115/1.4032518 ◽

2016 ◽

Vol 138 (3) ◽

Cited By ~ 2

Author(s):

Mukund Dutt Sharma ◽

Rakesh Sehgal ◽

Mohit Pant

Keyword(s):

Wear Rate ◽

Coefficient Of Friction ◽

Friction And Wear ◽

Experimental Results ◽

Contact Temperature ◽

Dry Sliding ◽

Sliding Velocity ◽

Average Coefficient ◽

Maximum Contact ◽

Friction And Wear Characteristics

Modeling of dry sliding friction and wear behavior of Ti3Al2.5V alloy sliding against EN31 steel using a multi-tribotester has been presented. Mathematical model equations in the form of natural log transformation for wear rate (WR), average coefficient of friction (μa), and a square root transformation for maximum contact temperature (Tm) considering the effect of tribological variables have been developed and validated by comparing them with the experimental results. The authors claim novelty with regard to modeling and optimization of friction and wear characteristics of Ti-3Al2.5V alloy. The results reveal that the magnitude of wear rate and maximum contact temperature increases with increase in sliding velocity and increasing normal load with few exceptions. Whereas average coefficient of friction first increases with increasing sliding velocity up to 2.51 m/s, and then decreases at highest sliding velocity. The load is found to have strongest influence on both wear rate and average coefficient of friction followed by sliding velocity, whereas sliding velocity has strongest influence on the maximum contact temperature followed by load. The perturbation plot results are also in accordance with the analysis of variance (ANOVA) analysis. The theoretical and experimental results have an average error of 5.06%, 1.78%, and 1.42%, respectively, for wear rate, average coefficient of friction, and maximum contact temperature. Optimization resulted in a maximum desirability of 0.508 at a load of 60 N and a sliding velocity of 1.5 m/s. For these values, the predicted minimum wear rate is 0.0001144 g/m, the coefficient of friction is 0.3181, and the tool-tip temperature is 59.03 °C.

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The Coefficient of Friction of Soccer Balls

Proceedings ◽

10.3390/proceedings2020049092 ◽

2020 ◽

Vol 49 (1) ◽

pp. 92

Author(s):

Adin Ming Tan ◽

Yehuda Weizman ◽

Firoz Alam ◽

Franz Konstantin Fuss

Keyword(s):

Coefficient Of Friction ◽

Average Velocity ◽

Normal Force ◽

Force Plate ◽

Average Coefficient ◽

The Coefficient Of Friction

Nine soccer balls were tested for their friction against a leather sheet, using a force plate. An average normal force of 63.6 N was applied and the movement of the ball had an average velocity of 15 mm/s. Each test was repeated 15 times and the average Coefficient of Friction (COF) was reported. The following results were obtained: Jabulani (COF: 0.62 ± 0.05); Fracas (COF: 0.41 ± 0.01); Ordem 3 (COF: 0.63 ± 0.02); Teamgeist (COF: 0.38 ± 0.01); Brazuca (COF: 0.45 ± 0.01); Kopanya (COF: 0.39 ± 0.01); React (COF: 0.37 ± 0.01); Finale 15 (COF: 0.39 ± 0.06); Vintage T-panel leather ball (COF: 0.41 ± 0.02). Overall, the COF of all balls tested ranged between 0.37 and 0.62. The Finale 15 ball showed a decreasing COF trend with repeated trials and the React ball produced pronounced slip-stick phenomenon.

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Analysis of sliding friction of WC-Co composite on particleboard

Annals of WULS, Forestry and Wood Technology ◽

10.5604/01.3001.0014.6711 ◽

2020 ◽

Vol 111 ◽

pp. 60-67

Author(s):

Jacek Wilkowski ◽

Marek Barlak ◽

Radosław Jałocha ◽

Zbigniew Werner ◽

Alicja Auriga

Keyword(s):

Surface Roughness ◽

Friction Coefficient ◽

Coefficient Of Friction ◽

Sliding Friction ◽

Roughness Parameter ◽

Average Increase ◽

Average Coefficient ◽

Before And After ◽

The Coefficient Of Friction ◽

Nano Size

Analysis of sliding friction of WC-Co composite on particleboard. The paper presents the analysis of the coefficient of friction at the contact area between WC-Co composite and particleboard. The four types of WC-Co composite in the form of milling indexable knives for wood materials machining were tested. The tests were carried out on a linear reciprocating tribotester (pin-on-flat), where the sample was the clearance surface of WC-Co indexable knives and the counter-sample was made of three-layer particleboard. Before and after tribological tests, the surface roughness of tested knives was measured. The highest values of friction coefficient were obtained for the type UMG04 of cemented carbide - with nano size of WC grains and the lowest content of cobalt. The average coefficient of friction for selected types of WC-Co correlated with the average increase in surface roughness (the roughness parameter Ry).

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In vivo friction properties of human skin

Prosthetics and Orthotics International ◽

10.3109/03093649909071625 ◽

1999 ◽

Vol 23 (2) ◽

pp. 135-141 ◽

Cited By ~ 182

Author(s):

M. Zhang ◽

A. F. T. Mak

Keyword(s):

Human Skin ◽

Coefficient Of Friction ◽

Normal Subjects ◽

Controlled Environment ◽

Frictional Properties ◽

Average Coefficient ◽

Palm Of The Hand

In vivo frictional properties of human skin and five materials, namely aluminium, nylon, silicone, cotton sock, Pelite, were investigated. Normal and untreated skin over six anatomic regions of ten normal subjects were measured under a controlled environment. The average coefficient of friction for all measurements is 0.46±0.15 (p < 0.05). Among all measured sites, the palm of the hand has the highest coefficient of friction (0.62±0.22). For all the materials tested, silicone has the highest coefficient of friction (0.61±0.21), while nylon has the lowest friction (0.37±0.09).

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