scholarly journals Experimental investigation of granular friction behaviors during reciprocating sliding

Friction ◽  
2021 ◽  
Author(s):  
Xuejie Zhang ◽  
Wei Sun ◽  
Wei Wang ◽  
Kun Liu
Keyword(s):  
External Load ◽  
Time History ◽  
Force Chain ◽  
Granular System ◽  
Sliding Velocity ◽  
Reciprocating Sliding ◽  
Experimental Apparatus ◽  
The Coefficient Of Friction ◽  
Half Loop ◽  
Granular Friction

AbstractGranular friction behaviors are crucial for understanding the ubiquitous packing and flow phenomena in nature and industrial production. In this study, a customized experimental apparatus that can simultaneously measure the time history of normal and tangential forces on the inside-shearing unit is employed to investigate the granular friction behaviors during a linear reciprocating sliding process. It is observed that the evolution behaviors of two normal forces distributed separately on the shearing unit can qualitatively reflect the effects of the force chain network. During the half-loop of the reciprocating sliding, the total normal force, which indicates the load-bearing capacity of the granular system, experiences the following typical stages: decreases abruptly and stabilizes momentarily, further decreases significantly to the minimum, gradually increases to the maximum, and then remains stable. These stages are associated closely with the relaxation, collapse, reconstruction, and stabilization of the force chain, respectively. Interestingly, the coefficient of friction (COF) can reach a stable value rapidly within the initial sliding stage and subsequently remain constant. The average COF within stable ranges decreases significantly with the external load G in the power-function form, G−0.5. Meanwhile, the COF increases slightly with the sliding velocity. Finally, a complete illustration of the dependences of the granular COF on the external load and sliding velocity is provided. Our study contributes to granular friction research by providing an innovative experimental approach for directly measuring the COF and implicitly correlating the evolution of the force chain network.

scholarly journals Finger pad friction and its role in grip and touch

2013 ◽  
Vol 10 (80) ◽  
pp. 20120467 ◽  
Author(s):  
Michael J. Adams ◽  
Simon A. Johnson ◽  
Philippe Lefèvre ◽  
Vincent Lévesque ◽  
Vincent Hayward ◽  
...  
Keyword(s):  
Contact Zone ◽  
Coefficient Of Friction ◽  
Normal Load ◽  
Theoretical Models ◽  
Tactile Perception ◽  
Major Influence ◽  
Sliding Velocity ◽  
Stick Slip ◽  
The Coefficient Of Friction ◽  
Finger Pad

Many aspects of both grip function and tactile perception depend on complex frictional interactions occurring in the contact zone of the finger pad, which is the subject of the current review. While it is well established that friction plays a crucial role in grip function, its exact contribution for discriminatory touch involving the sliding of a finger pad is more elusive. For texture discrimination, it is clear that vibrotaction plays an important role in the discriminatory mechanisms. Among other factors, friction impacts the nature of the vibrations generated by the relative movement of the fingertip skin against a probed object. Friction also has a major influence on the perceived tactile pleasantness of a surface. The contact mechanics of a finger pad is governed by the fingerprint ridges and the sweat that is exuded from pores located on these ridges. Counterintuitively, the coefficient of friction can increase by an order of magnitude in a period of tens of seconds when in contact with an impermeably smooth surface, such as glass. In contrast, the value will decrease for a porous surface, such as paper. The increase in friction is attributed to an occlusion mechanism and can be described by first-order kinetics. Surprisingly, the sensitivity of the coefficient of friction to the normal load and sliding velocity is comparatively of second order, yet these dependencies provide the main basis of theoretical models which, to-date, largely ignore the time evolution of the frictional dynamics. One well-known effect on taction is the possibility of inducing stick–slip if the friction decreases with increasing sliding velocity. Moreover, the initial slip of a finger pad occurs by the propagation of an annulus of failure from the perimeter of the contact zone and this phenomenon could be important in tactile perception and grip function.

scholarly journals Contact pressure and sliding velocity ranges in sheet metal forming simulations

2021 ◽  
Author(s):  
Joseba Cillaurren ◽  
Lander Galdos ◽  
Mario Sanchez ◽  
Alaitz Zabala ◽  
Eneko Saenz de Argandoña ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Contact Pressure ◽  
Sheet Metal ◽  
Coefficient Of Friction ◽  
Sheet Metal Forming ◽  
Metal Forming ◽  
Sliding Velocity ◽  
Wide Range ◽  
The Coefficient Of Friction ◽  
Friction Models

In the last few years many efforts have been carried out in order to better understand what the real contact between material and tools is. Based on the better understanding new friction models have been developed which have allowed process designers to improve numerical results in terms of component viability and geometrical accuracy. The new models define the coefficient of friction depending on different process parameters such as the contact pressure, the sliding velocity, the material strain, and the tool temperature. Many examples of the improvements achieved, both at laboratory scale and at industrial scale, can be found in the recent literature. However, in each of the examples found in the literature, different ranges of the variables affecting the coefficient of friction are covered depending on the component analysed and the material used to produce such component. The present work statistically analyses the contact pressure and sliding velocity ranges achieved during numerical simulation (FEM) of sheet metal forming processes. Nineteen different industrial components representing a high variety of shapes have been studied to cover a wide range of casuistic. The contact pressure and sliding velocity corresponding to typical areas of the tooling have been analysed though numerical simulation in each case. This study identifies the ranges of contact-pressure and sliding velocities occurring in sheet metal forming aimed to set the characterization range for future friction studies.

scholarly journals Effect of the coefficient of restitution and friction in the granular Leidenfrost effect in the absence of gravity. A numerical study

2021 ◽  
Vol 249 ◽  
pp. 14016
Author(s):  
Daniel Schiochet Nasato ◽  
Heiko Briesen
Keyword(s):  
Coefficient Of Friction ◽  
Parametric Study ◽  
Granular Media ◽  
Numerical Study ◽  
Packing Fraction ◽  
Coefficient Of Restitution ◽  
Granular System ◽  
The Coefficient Of Friction ◽  
Leidenfrost Effect ◽  
Microgravity Conditions

In this study the granular Leidenfrost effect in the absence of gravity is investigated numerically by means of the discrete element method. Apart from identifying the phenomena, a parametric study to quantify the influence of the coefficient of restitution and friction in the packing fraction of the granular media is carried on numerically. Surprisingly, both the coefficient of restitution and the coefficient of friction exhibit an influence of the same magnitude in the packing fraction of the granular system, which has not been reported in experiments and simulation of granular Leidenfrost regime under gravity or microgravity conditions.

Sensitivity of the Effective Seismic Support Damping in a Class I Piping System to Analysis Parameters

2009 ◽  
Author(s):  
Nima Zobeiry
Keyword(s):  
Seismic Analysis ◽  
Response Spectrum ◽  
Time History ◽  
Class I ◽  
Piping System ◽  
Frequency Content ◽  
Response Spectrum Analysis ◽  
History Analysis ◽  
The Coefficient Of Friction ◽  
Seismic Damping

It is understood that the level of seismic damping in a piping system is strongly influenced by the supports. Put differently, the supports contribute to an effective damping that can be considered in the seismic analysis of the piping system. This paper investigates the issue for the feeder pipes of a CANDU™ reactor. Feeders are numerous class I pipes in parallel, which are separated by frictional spacer elements. The results of a time history analysis, taking into account different damping mechanisms, are compared to those from a response spectrum analysis to deduce the effective damping in the system. The sensitivity of the effective damping to different parameters, such as the coefficient of friction and the input frequency content, is investigated.

Coefficient of Friction for Aluminum Alloy Sheet in Contact with Polyurethane Rubber

2010 ◽  
Vol 26-28 ◽  
pp. 320-325 ◽  
Author(s):  
Li Li Wang ◽  
Dong Sheng Li ◽  
Xiao Qiang Li ◽  
Liang Wang ◽  
Wei Jun Yang
Keyword(s):  
Aluminum Alloy ◽  
Coefficient Of Friction ◽  
Normal Load ◽  
Orthogonal Experimental Design ◽  
Sliding Velocity ◽  
Stretch Forming ◽  
Forming Process ◽  
Alloy Material ◽  
The Coefficient Of Friction ◽  
The Impact

Stretch forming process of aircraft skin over reconfigurable compliant tooling is a new technology in skin manufacturing. During this process, the coefficient of friction is important for modeling accurately the process of stretch forming. The objective of this research is to measure the coefficient of friction for aluminum alloy in contact with polyurethane rubber in reciprocal sliding. An orthogonal experimental design was used to reveal the impact of four factors on the coefficient of friction, including lubrication, normal load, aluminum alloy material and sliding velocity. It is shown that lubrication is a major factor, sliding velocity is a minor factor. The influence of normal pressure is less than sliding velocity and the influence of aluminum alloy material is not very obvious. Finally, based on the experiment results, the selections of lubricant and stretching velocity are discussed in order to improve the process of stretch forming.

XXIII.—On the Cohesion of Steel, and on the Relation between the Yield Points in Tension and in Compression.

1908 ◽  
Vol 28 ◽  
pp. 374-381 ◽  
Author(s):  
G. H. Gulliver
Keyword(s):  
Mild Steel ◽  
Yield Point ◽  
Coefficient Of Friction ◽  
External Load ◽  
Frictional Resistance ◽  
Experimental Results ◽  
Cohesive Force ◽  
Metallic Particles ◽  
Resistance To Deformation ◽  
The Coefficient Of Friction

SUMMARY(a) On the assumptions that resistance to deformation is due to simple friction, and that the coefficient of friction is independent of the load, the ratio of the yield point in tension to the yield point in compression, for what is ordinarily known as mild steel, is calculated as 2·384 to 3·384, or as 0·705 to 1. Experimental results so far obtained do not agree well with these figures, the value for the tensile yield point being relatively high, and that for compression relatively low.(b) On the further assumption that a cohesive force acting between the metallic particles gives rise to a frictional resistance which may be added (algebraically) to that due to the effect of the external load, the value of this cohesive force is deduced as equal to 3·384 times the stress which corresponds with the tension yield point, or to 2·384 times that corresponding with the compression yield point. Experimental results from a large number of tests agree very fairly with the calculated figures for the case of tension.

Worm Gear Performance

1935 ◽  
Vol 129 (1) ◽  
pp. 127-194 ◽  
Author(s):  
Henry E. Merritt
Keyword(s):  
Comparative Method ◽  
Worm Gear ◽  
Line Contact ◽  
Simple Method ◽  
Geometrical Properties ◽  
Gear Teeth ◽  
Experimental Apparatus ◽  
Load Carrying ◽  
The Coefficient Of Friction ◽  
Worm Gears

The paper represents an attempt to establish a basis upon which the load-carrying capacity and efficiency of worm gears may be predicted. It forms a supplement to a forthcoming British Standard Specification. The requirements of a worm thread profile are briefly considered and the use of the involute helicoid as a basis of worm thread design is recommended. The geometrical properties of the involute helicoid are discussed and a simple method of determining the zone and lines of contact is given. On a theorem on the curvature of tooth profiles as basis, the relative curvature of worm threads and wheel teeth is determined. A method of comparing the stress conditions between lubricated surfaces making moving line-contact is presented and its application to the determination of the allowable loading on worm gear teeth results in simple formulæ. A comparative method of determining wheel tooth strength is also given. An experimental apparatus has been developed for investigating the friction between surfaces in lubricated line-contact, and some of the results obtained therefrom are described. The relation between the results obtained from rolling and sliding disks and from actual worm gears is discussed, and average values of the coefficient of friction which may be used in design are given.

scholarly journals Tribological studies of different bioimplant materials for orthopedic application using Taguchi experimental design

2021 ◽  
Vol 38 (3−4) ◽  
Author(s):  
Sachin Solanke ◽  
Vivek Gaval
Keyword(s):  
Weight Loss ◽  
Coefficient Of Friction ◽  
Friction And Wear ◽  
Normal Load ◽  
Individual Contribution ◽  
Sliding Velocity ◽  
Wear Weight Loss ◽  
Taguchi Design Of Experiments ◽  
The Coefficient Of Friction ◽  
Material Factor

In this research ball on disc wear tests have been carried out with ASTM G-99 standard at room temperature in simulated body fluid. The tribological property such as the coefficient of friction and wear weight loss was studied by using the Taguchi design of experiments. The design of the experiment was done using L8 orthogonal array to determine the collective contribution of the wear parameters. An analysis of variance demonstrated that the individual contribution of type of material factor was 97.15% and 66.66% for the coefficient of friction and wear weight loss respectively, which is the highest individual contribution as compared to other factors. It was concluded that the coefficient of friction and wear weight loss is mainly influenced by type of material factor. The analysis of the signal-to-noise ratio shows that the optimal coefficient of friction and wear weight loss was obtained with CoCrMo material at an applied normal load of 5 N with a sliding velocity of 0.05 m/s for a track diameter of 30 mm. To check the accuracy of results a confirmation test was carried out which indicates that predicted values are very close to the experimental values and the model is significant to predict the coefficient of friction. The results showed that the coefficient of friction and wear weight loss increases with increasing the applied load and sliding velocity. The microstructure of all substrates materials was analyzed using a scanning electron microscope. Wear track study showed that adhesive dominant wear mechanism for all four different substrate materials.

Effect of contact temperature, normal load and dry sliding velocity on the coefficient of friction and wear behavior of nickel based super alloy

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Rama Krishna S. ◽  
Patta Lokanadham
Keyword(s):  
Coefficient Of Friction ◽  
Friction And Wear ◽  
Wear Behavior ◽  
Normal Load ◽  
Contact Temperature ◽  
Sliding Velocity ◽  
Friction And Wear Behavior ◽  
Alloy Material ◽  
The Coefficient Of Friction ◽  
Super Alloy

Purpose The purpose of the present paper aims to, study the coefficient of friction and wear behavior of nickel based super alloys used in manufacturing of gas and steam turbine blades. In present paper, parametric study focuses on normal load, dry sliding velocity and contact temperature influence on coefficient of friction and wear of a nickel based super alloy material. Design/methodology/approach Experimental investigation is carried out to know the effect of varying load at constant sliding velocity and varying sliding velocity at constant load on coefficient of friction and wear behavior of nickel based super alloy material. The experiments are carried out on a nickel based super alloy material using pin on disk apparatus by load ranging from 30 N to 90 N and sliding velocity from 1.34 m/s to 2.67 m/s. The contact temperature between pin and disk is measured using K-type thermocouple for all test conditions to know effect of contact temperature on coefficient of friction and wear behavior of nickel based super alloy material. Analytical calculations are carried out to find wear rate and wear coefficient of the test specimen and are compared with experimental results for validation of experimental setup. Regression equations are generated from experimental results to estimate coefficient of friction and wear in the range of test conditions. Findings From the experimental results, it is observed that by increasing the normal load or sliding velocity, the contact temperature between the pin and disk increases, the coefficient of friction decreases and wear increases. Analysis of variance (ANOVA) is used to study the influence of individual parameters like normal load, dry sliding speed and sliding distance on the coefficient of friction and wear of nickel based super alloy material. Originality/value This is the first time to study effect of contact temperature on the coefficient of friction and wear behavior of nickel-based super alloy used for gas and steam turbine blades. Separate regression equations have been developed to determine the coefficient of friction and wear for the entire range of speed of gas turbine blades made of nickel based super alloy. The regression equations are also validated against experimental results.

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