Apparent Coefficient of Friction of Wheat on Bin Wall Material

1989 ◽  
Vol 32 (5) ◽  
pp. 1769-1773 ◽  
Author(s):  
R. A. Bucklin ◽  
S. A. Thompson ◽  
I. J. Ross ◽  
R. H. Biggs
Keyword(s):  
Coefficient Of Friction ◽  
Wall Material ◽  
Apparent Coefficient Of Friction

Apparent Coefficient of Friction of Wheat on Denim

2017 ◽  
Vol 23 (3) ◽  
pp. 175-181 ◽  
Author(s):  
Charles V. Schwab
Keyword(s):  
Standard Deviation ◽  
Moisture Content ◽  
Bulk Density ◽  
Coefficient Of Friction ◽  
Current Understanding ◽  
Farm Safety ◽  
The Coefficient Of Friction ◽  
Denim Fabric ◽  
Apparent Coefficient Of Friction

Abstract. Calculation of the extraction force for a grain entrapment victim requires a coefficient of friction between the grain and the surface of the victim. Because denim is a common fabric for the work clothes that cover entrapment victims, the coefficient of friction between grain and denim becomes necessary. The purpose of this research was to calculate the apparent coefficient of friction of wheat on denim fabric using a proven procedure. The expectation is to improve the current understanding of conditions that influence extraction forces for victims buried in wheat. The apparent coefficient of friction of wheat on denim fabric was calculated to be 0.167 with a standard deviation of ±0.013. The wheat had a moisture content of 10.7% (w.b.) and bulk density of 778.5 kg m-3. The apparent coefficient of friction of wheat on denim was not significantly affected by pull speeds of 0.004, 0.008, and 0.021 mm s-1 nor normal grain pressures of 3.2, 4.8, 6.3, 7.9, and 11.1 kPa. This is a beginning of understanding the conditions that influence the extraction forces for grain entrapment victims. Keywords: Farm safety, Grain entrapment, Grain rescue, Grain extraction.

Friction of a Rubber Wedge Sliding on Glass

1991 ◽  
Vol 64 (1) ◽  
pp. 108-117 ◽  
Author(s):  
C. W. Extrand ◽  
A. N. Gent ◽  
S. Y. Kaang
Keyword(s):  
Coefficient Of Friction ◽  
Applied Load ◽  
Unit Length ◽  
Sliding Speed ◽  
Normal Loading ◽  
Contact Width ◽  
Wide Range ◽  
The Coefficient Of Friction ◽  
Apparent Coefficient Of Friction ◽  
Pressure Independent

Abstract The contact width, and hence contact area, for an elastic wedge pressed against a rigid flat surface appears to be proportional to the applied load per unit length. For a particular rubber sample, the reciprocal of the constant of proportionality, i.e., the mean normal pressure, was 130 kPa, i.e., about 7% of the tensile modulus E of the material. It was also independent of sliding speed over the range examined. Thus, a sharp wedge gave a relatively high loading pressure, independent of the applied load. As a result, the coefficient of friction was also independent of applied load over a wide range. The coefficient of friction was measured for a wedge of an unfilled natural rubber vulcanizate over wide ranges of sliding speed (50 µm/s to 100 mm/s) and test temperature (3°C to 63°C). It was found to increase with sliding speed and decrease with temperature over these ranges. The results at different temperatures were superposable using the WLF rate-temperature equivalence to create a master curve of friction vs. reduced sliding speed, rising from a value of about 1.5 at high temperatures and low speeds to about 5 at low temperatures and high speeds. Chlorination of a thin surface region reduced the coefficient of friction and its dependence on speed and temperature. It then became similar to that typically found for thermoplastics, 0.4 to 0.7. The geometry of sliding a flexible strip against a rigid curved surface caused high values of the apparent coefficient of friction to be obtained at relatively small departures from normal loading. In an extreme case, frictional seizure was observed when a high-friction sample contacted the glass surface at an angle of about 15° to the direction of loading. The apparent coefficient of friction then became indefinitely large. This same phenomenon of abnormally large frictional effects would be expected to occur in the case of conventional windshield-wiper blades, sliding over curved glass windshields.

scholarly journals Effect of minimum quantity lubrication strategies on tribological study of simulated machining operation

2019 ◽  
Vol 20 (6) ◽  
pp. 624 ◽  
Author(s):  
Sana Werda ◽  
Arnaud Duchosal ◽  
Guénhaël Le Quilliec ◽  
Antoine Morandeau ◽  
René Leroy
Keyword(s):  
Coefficient Of Friction ◽  
Minimum Quantity Lubrication ◽  
Front Face ◽  
Rake Face ◽  
Steel Cylinder ◽  
Tribological Tests ◽  
Flank Face ◽  
Apparent Coefficient Of Friction ◽  
Frictional Behaviour ◽  
Cooling Ability

The main aim of this paper was to reproduce the frictional behaviour that occurred in milling with a pin-on-cylinder system. Three different tribological tests were conducted reproducing friction phenomenon that happened in three machining conditions: (i) dry rubbing, representing the dry machining condition, (ii) MQL applied to front face rubbing which was similar to milling with MQL applied on the insert rake face and (iii) MQL applied to rear end rubbing which was similar to milling with MQL applied on flank face. Tribological tests were carried out with coated tungsten carbide pins rubbing on X100CrMoV5 steel cylinder. Apparent coefficient of friction, adhesion area and heat flux transmitted to the pin were analysed. It has been shown that MQL rear end rubbing provided a lower adhesion area and lower apparent coefficient of friction than with MQL front face rubbing. Furthermore, MQL rear end rubbing resulted in a greater cooling ability. These findings helped to explain why better results were obtained with MQL flank face lubrication in milling compared to MQL rake face lubrication.

Apparent Dynamic Coefficient of Friction of Corn on Galvanized Steel Bin Wall Material

1993 ◽  
Vol 36 (6) ◽  
pp. 1915-1918 ◽  
Author(s):  
R. A. Bucklin ◽  
S. A. Thompson ◽  
I. J. Ross ◽  
R. H. Biggs
Keyword(s):  
Coefficient Of Friction ◽  
Galvanized Steel ◽  
Wall Material ◽  
Dynamic Coefficient ◽  
Dynamic Coefficient Of Friction

Variation in the Apparent Coefficient of Friction of Wheat on Galvanized Steel

1988 ◽  
Vol 31 (5) ◽  
pp. 1518-1524 ◽  
Author(s):  
S. A. Thompson ◽  
R. A. Bucklin ◽  
C. D. Batich ◽  
I. J. Ross
Keyword(s):  
Coefficient Of Friction ◽  
Galvanized Steel ◽  
Apparent Coefficient Of Friction

Analytical Modelling of Friction Along Tool Chip Interface for Inconel 718

2017 ◽  
Author(s):  
Abhishek Kumar ◽  
Basil Kuriachen ◽  
Surender Ontela
Keyword(s):  
Shear Zone ◽  
Analytical Model ◽  
Coefficient Of Friction ◽  
Inconel 718 ◽  
Weight Ratio ◽  
Constant Thickness ◽  
Depth Of Cut ◽  
Shear Stresses ◽  
Apparent Coefficient Of Friction ◽  
Secondary Shear Zone

Inconel 718 is gaining its importance in the aerospace and power plant industries because of its high strength to weight ratio. The lack of understanding of the tool chip interface for Inconel 718 restricts the prediction of the apparent coefficient of friction and thus the cutting forces, thereby the machining efficiency. In the present study an analytical model has been developed accounting the actual variation of stresses over the rake face. The model focuses on the variation of shear stresses in the sticking region and has been considered to be increasing exponentially with distance from tool tip. The primary shear zone is assumed to be a thin layer with constant thickness and has been modelled using Johnson Cook material model. The shear stresses at the entry and exit of the primary shear zone has been calculated using iterative techniques proposed in the literature. The secondary shear zone has been analyzed dividing the contact length into two distinct regions and each region has been dealt separately. The ratio of real area of contact to the apparent area of contact has been given consideration and dealt with at macroscopic level. Experimental values have been extracted from previous studies on Inconel 718. The predictions of the analytical model was found to be in good agreement with experimental results. The experimental apparent coefficient of friction was obtained as 0.5119 against 0.4733 from the developed model at a velocity of 70 mm/min, depth of cut of 1mm, nose radius of 0.8mm and with negative rake angle (−6°) with CNMG0812 tool. The predicted and the experimental friction coefficient showed a variation of 7.07% – 10% and thus can serve as reliable model for Inconel 718.

Silica Incorporation in the Cell Wall of the Singing Cell of Urtica dioica

1975 ◽  
Vol 33 ◽  
pp. 584-585
Author(s):  
A. E. Sowers ◽  
E. L. Thurston
Keyword(s):  
Cell Wall ◽  
Unique Feature ◽  
Urtica Dioica ◽  
Wall Material ◽  
Pain Response ◽  
Apical Portion ◽  
Ultrastructural Investigation ◽  
Plant Families ◽  
Bulbous Tip

Plant stinging emergences exhibit functional similarities in that they all elicit a pain response upon contact. A stinging emergence consists of an elongated stinging cell and a multicellular pedestal (Fig. 1). A recent ultrastructural investigation of these structures has revealed the ontogeny and morphology of the stinging cells differs in representative genera in the four plant families which possess such structures. A unique feature of the stinging cell of Urtica dioica is the presence of a siliceous cell wall in the apical portion of the cell. This rigid region of the cell wall is responsible for producing the needle-like apparatus which penetrates the skin. The stinging cell differentiates the apical bulbous tip early in development and the cell continues growth by intercalary addition of non-silicified wall material until maturity.The uppermost region of the stinging cell wall is entirely composed of silica (Fig. 2, 3) and upon etching with a 3% solution of HF (5 seconds), the silica is partially removed revealing the wall consisting of individualized silica bodies (Fig. 4, 5).

Microcapsules containing Pterodon pubescens Benth. extract with cashew gum as wall material

Planta Medica ◽  
2014 ◽  
Vol 80 (16) ◽  
Author(s):  
LR Giarola ◽  
N de Cássia Almeida Queiroz ◽  
IM de Oliveira Sousa ◽  
RA Ferreira Rodrigues ◽  
MA Foglio ◽  
...  
Keyword(s):  
Wall Material ◽  
Cashew Gum

An Analytical Thermodynamic Approach to Friction of Rubber on Ice

2012 ◽  
Vol 40 (2) ◽  
pp. 124-150
Author(s):  
Klaus Wiese ◽  
Thiemo M. Kessel ◽  
Reinhard Mundl ◽  
Burkhard Wies
Keyword(s):  
Coefficient Of Friction ◽  
Liquid Layer ◽  
Contact Area ◽  
Leading Edge ◽  
Viscous Friction ◽  
Analytical Approximation ◽  
Real Contact Area ◽  
Length Scales ◽  
Real Contact ◽  
Ice Surface

ABSTRACT The presented investigation is motivated by the need for performance improvement in winter tires, based on the idea of innovative “functional” surfaces. Current tread design features focus on macroscopic length scales. The potential of microscopic surface effects for friction on wintery roads has not been considered extensively yet. We limit our considerations to length scales for which rubber is rough, in contrast to a perfectly smooth ice surface. Therefore we assume that the only source of frictional forces is the viscosity of a sheared intermediate thin liquid layer of melted ice. Rubber hysteresis and adhesion effects are considered to be negligible. The height of the liquid layer is driven by an equilibrium between the heat built up by viscous friction, energy consumption for phase transition between ice and water, and heat flow into the cold underlying ice. In addition, the microscopic “squeeze-out” phenomena of melted water resulting from rubber asperities are also taken into consideration. The size and microscopic real contact area of these asperities are derived from roughness parameters of the free rubber surface using Greenwood-Williamson contact theory and compared with the measured real contact area. The derived one-dimensional differential equation for the height of an averaged liquid layer is solved for stationary sliding by a piecewise analytical approximation. The frictional shear forces are deduced and integrated over the whole macroscopic contact area to result in a global coefficient of friction. The boundary condition at the leading edge of the contact area is prescribed by the height of a “quasi-liquid layer,” which already exists on the “free” ice surface. It turns out that this approach meets the measured coefficient of friction in the laboratory. More precisely, the calculated dependencies of the friction coefficient on ice temperature, sliding speed, and contact pressure are confirmed by measurements of a simple rubber block sample on artificial ice in the laboratory.

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