scholarly journals Wax-oil lubricants to reduce the shear between skin and PPE

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Kian Kun Yap ◽  
Manoj Murali ◽  
Zhengchu Tan ◽  
Xue Zhou ◽  
Luli Li ◽  
...  
Keyword(s):  
Olive Oil ◽  
Coefficient Of Friction ◽  
Static Friction ◽  
Mineral Oil ◽  
The Coefficient Of Friction ◽  
Friction Measurements ◽  
Lubricant Application ◽  
Static Coefficient Of Friction

AbstractProlonged use of tight-fitting PPE, e.g., by COVID-19 healthcare workers leads to skin injuries. An important contributor is the shear exerted on the skin due to static friction at the skin-PPE interface. This study aims to develop an optimised wax-oil lubricant that reduces the friction, or shear, in the skin-PPE contact for up to four hours. Lubricants with different wax-oil combinations were prepared using beeswax, paraffin wax, olive oil, and mineral oil. In-vivo friction measurements involving seven participants were conducted by sliding a polydimethylsiloxane ball against the volar forearms to simulate the skin-PPE interface. The maximum static coefficient of friction was measured immediately and four hours after lubricant application. It was found that the coefficient of friction of wax-oil lubricants is mainly governed by the ratio of wax to oil and the thermal stability and morphology of the wax. To maintain long-term lubricity, it is crucial to consider the absorption of oil into the PPE material. The best performing lubricant is a mixture of 20 wt% beeswax, 40 wt% olive oil, and 40 wt% mineral oil, which compared to unlubricated skin, provides 87% (P = 0.0006) and 59% (P = 0.0015) reduction in instantaneous and 4-h coefficient of friction, respectively.

scholarly journals Wax-Oil Lubricants to Reduce the Shear Between Skin and PPE

2021 ◽  
Author(s):  
Kian Kun Yap ◽  
Manoj Murali ◽  
Zhengchu Tan ◽  
Xue Zhou ◽  
Luli Li ◽  
...  
Keyword(s):  
Olive Oil ◽  
Coefficient Of Friction ◽  
Static Friction ◽  
Mineral Oil ◽  
The Coefficient Of Friction ◽  
Friction Measurements ◽  
Lubricant Application ◽  
Static Coefficient Of Friction

Abstract Prolonged use of tight-fitting PPE, e.g., by COVID-19 healthcare workers leads to skin injuries. An important contributor is the shear exerted on the skin due to static friction at the skin-PPE interface. This study aims to develop an optimised wax-oil lubricant that reduces the friction, or shear, in the skin-PPE contact for up to four hours. Lubricants with different wax-oil combinations were prepared using beeswax, paraffin wax, olive oil, and mineral oil. In-vivo friction measurements involving seven participants were conducted by sliding a polydimethylsiloxane ball against the volar forearms to simulate the skin-PPE interface. The maximum static coefficient of friction was measured immediately and four hours after lubricant application. It was found that the coefficient of friction of wax-oil lubricants is mainly governed by the ratio of wax to oil and the thermal stability and morphology of the wax. To maintain long-term lubricity, it is crucial to consider the absorption of oil into the PPE material. The best performing lubricant is a mixture of 20 wt% beeswax, 40 wt% olive oil, and 40 wt% mineral oil, which compared to unlubricated skin, provides 87% (P = 0.0006) and 59% (P = 0.0015) reduction in instantaneous and 4-hour coefficient of friction, respectively.

Static and Clinging Friction of Pivot Bearings

1944 ◽  
Vol 151 (1) ◽  
pp. 274-284
Author(s):  
M. C. Hunter
Keyword(s):  
Stainless Steel ◽  
Coefficient Of Friction ◽  
Rapid Growth ◽  
Static Friction ◽  
Clear Distinction ◽  
Special Apparatus ◽  
The Coefficient Of Friction

The author points out the clear distinction which has to be drawn between kinetic and static friction, and describes the special apparatus used in the investigation carried out to determine the static friction of various combinations of metals, including stainless steel and duralumin, under several conditions of dry and viscous lubrication. The paper stresses the effect of time, and gives data showing the rapid growth of the coefficient of friction during the first twenty-four hours at rest, and the subsequent increases over a period of five days. A series of long-term tests of thirty, sixty, and ninety days, on a selected number of specimens, provides a direct comparison from which the relative merits of the various combinations of materials is drawn. Evidence is provided suggesting advantages to be derived from the use of graphite as a preventative of clinging friction. In conclusion, an explanation is put forward as to the possible causes responsible for the building up of friction with the passage of time.

Floor Slipperiness Measurement in a Food Factory

2013 ◽  
Vol 303-306 ◽  
pp. 769-772
Author(s):  
Kai Way Li ◽  
Ching Chung Chen ◽  
Li Wen Liu ◽  
Chih Yong Chen
Keyword(s):  
Coefficient Of Friction ◽  
Safety Standard ◽  
The Usa ◽  
The Coefficient Of Friction ◽  
Friction Measurements ◽  
Ergonomic Interventions ◽  
Northern Taiwan

Floor slipperiness assessment was conducted in a food factory in northern Taiwan. Three areas in the popcorn sector of the factory were measured. The friction measurements were conducted using the Brungraber Mark II slipmeter. A total of 96 measurements of the coefficient of friction on the floor were conducted. In addition, six employees were interviewed concerning their experiences of slipping and falling in the sector and their perception of floor slipperiness. The results showed that all the readings in the measurement areas were lower than 0.5, a safety standard commonly adopted in the USA. All the interviewees reported that they had the experiences of slipping without falling in the sector. All of them reported the floor in the popping area was “extremely slipperiness.” Ergonomic interventions are required and in this sector.

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.

Frictional Vibrations

1955 ◽  
Vol 22 (2) ◽  
pp. 207-214
Author(s):  
David Sinclair
Keyword(s):  
Coefficient Of Friction ◽  
Equations Of Motion ◽  
Static Friction ◽  
Uniform Motion ◽  
Friction Characteristic ◽  
Stick Slip ◽  
The Coefficient Of Friction ◽  
Brake Lining ◽  
Solid Bodies ◽  
Frictional Vibrations

Abstract Frictional vibrations, such as stick-slip motion and automobile-brake squeal, which occur when two solid bodies are rubbed together, are analyzed mathematically and observed experimentally. The conditions studied are slow uniform motion and relatively rapid simple harmonic motion of brake lining over a cast-iron base. The equations of motion show and the observations confirm that frictional vibrations are caused primarily by an inverse variation of coefficient of friction with sliding velocity, but their form and occurrence are greatly dependent upon the dynamical constants of the mechanical system. With a constant coefficient of friction, the vibration initiated whenever sliding begins is rapidly damped out, not by the friction but by the “natural” damping of all mechanical systems. The coefficient of friction of most brake linings and other organic materials was essentially invariant with velocity, except that the static coefficient was usually greater than the sliding coefficient. Most such materials usually showed a small decrease in coefficient with increasing temperature. The persistent vibrations resulting from the excess static friction were reduced or eliminated by treating the rubbing surfaces with polar organic compounds which produced a rising friction characteristic.

Coefficients of Friction: Static Versus Dynamic

2020 ◽  
Author(s):  
Jack Youqin Huang
Keyword(s):  
Coefficient Of Friction ◽  
Frictional Force ◽  
Inertial Force ◽  
Static Friction ◽  
Theory And Practice ◽  
Dynamic Friction ◽  
Kinetic Friction ◽  
The Coefficient Of Friction ◽  
Static Versus Dynamic ◽  
New Discovery

Abstract This paper deals with the problem of static and dynamic (or kinetic) friction, namely the coefficients of friction for the two states. The coefficient of static friction is well known, and its theory and practice are commonly accepted by the academia and the industry. The coefficient of kinetic friction, however, has not fully been understood. The popular theory for the kinetic friction is that the coefficient of dynamic friction is smaller than the coefficient of static friction, by comparison of the forces applied in the two states. After studying the characteristics of the coefficient of friction, it is found that the comparison is not appropriate, because the inertial force was excluded. The new discovery in the paper is that coefficients of static friction and dynamic friction are identical. Wheel “locked” in wheel braking is further used to prove the conclusion. The key to cause confusions between the two coefficients of friction is the inertial force. In the measurement of the coefficient of static friction, the inertial force is initiated as soon as the testing object starts to move. Therefore, there are two forces acting against the movement of the object, the frictional force and the inertial force. But in the measurement of the coefficient of kinetic friction, no inertial force is involved because velocity must be kept constant.

In Vivo Estimation of the Coefficient of Friction between Extrinsic Flexor Tendons and Surrounding Structures in the Carpal Tunnel

1987 ◽  
Vol 31 (3) ◽  
pp. 323-324 ◽  
Author(s):  
Thomas J. Albin
Keyword(s):  
Coefficient Of Friction ◽  
Carpal Tunnel ◽  
Frictional Coefficient ◽  
Flexor Tendons ◽  
In Vivo Measurement ◽  
The Coefficient Of Friction

It has been suggested that the coefficient of friction between the finger flexor tendons and the structures over which they slide is normally quite small, but increases with irritation of the tendon. This paper utilizes a belt and pulley model of the wrist in the in vivo measurement of the frictional coefficient. An estimated value of 0.12 for the frictional coefficient was obtained from a sample of five symptom free subjects.

The Calculation of Roll Pressure in Hot and Cold Flat Rolling

1943 ◽  
Vol 150 (1) ◽  
pp. 140-167 ◽  
Author(s):  
E. Orowan
Keyword(s):  
Pressure Distribution ◽  
Yield Stress ◽  
Coefficient Of Friction ◽  
Static Friction ◽  
Rolled Stock ◽  
Theoretical Treatment ◽  
Frictional Drag ◽  
Roll Pressure ◽  
Plate Rolling ◽  
The Coefficient Of Friction

A numerical or graphical method is given for computing, in strip or plate rolling, the distribution of roll pressure over the arc of contact and the quantities derived from this (e.g. the vertical roll force, the torque, and the power consumption). The method avoids all mathematical approximations previously used in the theoretical treatment of rolling, and permits any given variation of the yield stress and of the coefficient of friction along the arc of contact to be taken into account. It can be used, therefore, in both hot and cold rolling, provided that the basic physical quantities (yield stress and coefficient of friction) are known. The usual assumption that the deformation could be regarded as a locally homogeneous compression has not been made, and the inhomogeneity of stress distribution has been taken into account approximately by using results derived by Prandtl and Nádai from the Hencky treatment of two-dimensional plastic deformation. It is found that the discrepancy between the roll pressure distribution curves calculated from the Kármán theory and those measured by Siebel and Lueg is due to the assumption in the theory that the frictional drag between the rolls and the rolled stock is equal to the product of the roll pressure and the coefficient of friction. If frictional effects are dominant, as in hot rolling, this product may easily exceed the yield stress in shear which is the natural upper limit to the frictional drag, and then static friction, instead of slipping, occurs. This has been taken into account in the present method, and the calculated curves of roll pressure distribution show good agreement with the curves measured by Siebel and Lueg.

scholarly journals Friction Behavior of Pre-Damaged Wet-Running Multi-Plate Clutches in an Endurance Test

Lubricants ◽  
2020 ◽  
Vol 8 (7) ◽  
pp. 68
Author(s):  
Thomas Schneider ◽  
Katharina Voelkel ◽  
Hermann Pflaum ◽  
Karsten Stahl
Keyword(s):  
Coefficient Of Friction ◽  
Later Life ◽  
Second Step ◽  
Experimental Investigations ◽  
Endurance Test ◽  
Friction Behavior ◽  
Speed Range ◽  
The Coefficient Of Friction ◽  
Endurance Tests

Wet-running multi-plate clutches should be prevented from failing due to the often safety-relevant functions they fulfill in the drive train. In addition to long-term damage, spontaneous damage is of particular relevance for failures. This paper focuses on the influence of spontaneous damage on frictional behavior in the later life cycle. The aim of the experimental investigations is to initially cause spontaneous damage in wet-running multi-plate clutches with sintered friction linings. For this purpose, three clutches are first pre-damaged in stage tests with different intensities, so that the first spontaneous damage (local discoloration, sinter transfer) occurs. In the second step, an endurance test is carried out with the pre-damaged clutch packs and a non-pre-damaged reference clutch. The friction behavior of the clutches during the endurance test is compared and evaluated. It shows that local discoloration and sinter transfer are no longer visible after the endurance tests. At the beginning of the endurance test, the values of coefficient of friction are higher over the entire speed range of the heavily pre-damaged clutches than with the slightly pre-damaged clutch and the non-pre-damaged reference clutch. At the end of the endurance test, it can be observed that the greater the pre-damage to the clutches is, the greater the coefficient of friction increases with decreasing sliding speed.

The Effect of Magnesium Carbonate (Chalk) on Geometric Entropy, Force, and Electromyography During Rock Climbing

2016 ◽  
Vol 32 (6) ◽  
pp. 553-557 ◽  
Author(s):  
Matthew A. Kilgas ◽  
Scott N. Drum ◽  
Randall L. Jensen ◽  
Kevin C. Phillips ◽  
Phillip B. Watts
Keyword(s):  
Coefficient Of Friction ◽  
Body Position ◽  
Muscular Activity ◽  
Magnesium Carbonate ◽  
Rock Climbing ◽  
The Body ◽  
Movement Sequence ◽  
The Coefficient Of Friction ◽  
Hands And Feet ◽  
Static Coefficient Of Friction

Rock climbers believe chalk dries the hands of sweat and improves the static coefficient of friction between the hands and the surface of the rock. The purpose of this study was to assess whether chalk affects geometric entropy or muscular activity during rock climbing. Nineteen experienced recreational rock climbers (13 males, 6 females; 173.5 ± 7.0 cm; 67.5 ± 3.4 kg) completed 2 climbing trails with and without chalk. The body position of the climber and muscular activity of the finger flexors was recorded throughout the trial. Following the movement sequence participants hung from a standard climbing hold until they slipped from the climbing structure, while the coefficient of friction and the ratio of the vertical forces on the hands and feet were determined. Although there were no differences in the coefficient of friction (P = .748), geometric entropy (P = .359), the ratio of the vertical forces between the hands and feet (P = .570), or muscular activity (P = .968), participants were able to hang longer after the use of chalk 62.9 ± 36.7 s and 49.3 ± 25.2 s (P = .046). This is advantageous because it may allow for prolonged rests, and more time to plan the next series of climbing moves.

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