The Hydrodynamic Phase of Gearbox Synchromesh Operation

1995 ◽  
Vol 209 (3) ◽  
pp. 203-211 ◽  
Author(s):  
B Paffoni ◽  
R Progri ◽  
J Blouët ◽  
R Gras
Keyword(s):  
Coefficient Of Friction ◽  
Shear Stresses ◽  
Force Output ◽  
Second Stage ◽  
Acceptable Accuracy ◽  
Output Torque ◽  
Friction Regime ◽  
The Coefficient Of Friction ◽  
Cone Surface ◽  
Ring Pair

The approach used is to divide the synchronization process into three distinct stages according to the friction regime operating, this idea being closely allied to that of A. E. Anderson (1972, SAE paper 750521). The authors proceed to derive a model for the first stage based on a shaft-ring pair with or without taper defects (angular mismatch). Expressions are derived for contact pressure (and hence axial force), output torque and the coefficient of friction, the latter pair being arrived at by considering the shear stresses acting at the cone surface. The results that are gained allow best and worst cases of torque and friction to be considered and the effect of circumferential grooves and axial slots to be theoretically examined, and the potential for this model in simulating such configurations is discussed. The main conclusion of the paper is that the coefficient of friction clearly decreases during the first stage such that the value during the second stage may be quite small (results of the analyses of the second and third stages are promised for the future), but it is now relatively simple to estimate this with acceptable accuracy.

An Analytical Solution for the Tapered Arbor Spring Slip Clutch

1974 ◽  
Vol 96 (3) ◽  
pp. 931-935
Author(s):  
T. R. Robe ◽  
S. E. Jones
Keyword(s):  
Analytical Solution ◽  
Coefficient Of Friction ◽  
Axial Force ◽  
Contact Forces ◽  
Output Torque ◽  
The Coefficient Of Friction ◽  
Spring Coil

An analytical solution is developed for the tapered arbor spring slip clutch by introducing approximations that do not appreciably affect the accuracy of the important clutch quantities. In addition, the influence of the coefficient of friction on the output torque, the axial force on the spring coil, and the radial contact forces alongthe tapered arbor are shown.

Shear and normal stresses measured on the Weissfluhjoch Snow Chute

2016 ◽  
Vol 53 (3) ◽  
pp. 445-454 ◽  
Author(s):  
Marius Schaefer
Keyword(s):  
Coefficient Of Friction ◽  
Normal Component ◽  
Flow Density ◽  
Shear Stresses ◽  
Normal Stresses ◽  
Flow Depth ◽  
Air Temperatures ◽  
Wet Snow ◽  
Before And After ◽  
The Coefficient Of Friction

Shear stresses on the running surface are believed to crucially determine the flow of snow avalanches. Measurements of shear and normal stresses on the running surface are presented as well as measurements of flow depth of snow flows down the Weissfluhjoch Snow Chute before and after a reduction of the chute’s inclination. In the measurements before the inclination change, maxima of measured normal stresses agreed with the maxima of the normal component of the column weight calculated using pre-release snow density. After the reduction of inclination, stresses increased considerably and the magnitude of the increase depended on the density of the flow. Using the measurements of normal stress and flow depth before the inclination change, a depth-averaged flow density was computed. The flow density was lower in the front and the tail of the avalanches and approached the pre-release density in the avalanche body. The ratio of measured shear to normal stresses, the coefficient of friction, was higher in wet snow flows than in dry snow flows. Upon analysis of the dependence of the coefficient of friction on parameters varying between the experiments, higher coefficients of friction for higher densities, snow and air temperatures, and average avalanche velocities were found. The total avalanche volume correlated negatively with the coefficient of friction. Measured coefficients of friction were generally lower as expected for flows of constant velocity, which might indicate the importance of other frictional processes such as friction at the snow–air interface, which is supported by the evolution of small dilute snow clouds on top of the flows that consisted of dry snow.

FORMULATION OF TOOL WEAR LAW WHEN CUTTING POLYMER COMPOSITES

2021 ◽  
pp. 36-45
Author(s):  
G. Khavin
Keyword(s):  
Wear Rate ◽  
Tool Wear ◽  
Contact Pressure ◽  
Tool Life ◽  
Coefficient Of Friction ◽  
Rear Surface ◽  
Shear Stresses ◽  
The Coefficient Of Friction ◽  
Wear Law ◽  
Over Time

Numerous experimental studies in the field of mechanical processing of composite materials for individual materials and tools made it possible to formulate particular models for describing tool wear, changing its microgeometry during operation and predicting durability. There are significant difficulties in measuring current wear and recalculation in mathematical models, since they include a large number of parameters. This does not allow for simple technical control of cutting edge wear and predicting tool life. The formulation of the wear-contact problem of the tool tip and the material interaction during turning of reinforced composite plastics is presented. Based on known studies, it is assumed that wear occurs along the flank of the tool, and is accompanied by an asymmetric change in the geometry of its tip. A model of abrasive wear during sliding of a tool tip rear surface with a polymer composite reinforcement material and fracture products is considered. It is assumed that the wear law is hereditary and there is a linear dependence of the wear rate on the rate of contact interaction and pressure. Shear stresses through the contact pressure and the coefficient of friction nonlinearly depend on the operating time of the tool due to the change due to wear in the geometric shape of the tool and the processing parameters of the product over time. The volumetric wear factor is a tool run time function. It reflects the fact that the interaction of the “tool-workpiece” pair with time should, as it were, forget about the running-in stage, which has a high wear rate, and the fact that the dependence of wear on the load (contact pressure) is characterized by the presence of aftereffect. A simplified relationship is obtained for the wear law under the assumption that there is no change in the coefficient of friction, temperature and contact pressure over time. Ultimately, to describe the wear law and predict the tool life, it is necessary to know a number of empirical constants, the values of which are determined by the change in the microgeometry of the tool tip during interaction during cutting.

Experimental Investigation of aluminum doping crumb rubber/epoxy composite in reciprocating motion

2015 ◽  
Vol 3 ◽  
pp. 1
Author(s):  
Goutam Chandra Karar ◽  
Nipu Modak
Keyword(s):  
Experimental Investigation ◽  
Coefficient Of Friction ◽  
Epoxy Composite ◽  
Normal Load ◽  
Crumb Rubber ◽  
The Other ◽  
Reciprocating Motion ◽  
Molding Process ◽  
Friction Tester ◽  
The Coefficient Of Friction

The experimental investigation of reciprocating motion between the aluminum doped crumb rubber /epoxy composite and the steel ball has been carried out under Reciprocating Friction Tester, TR-282 to study the wear and coefficient of frictions using different normal loads (0.4Kg, 0.7Kgand1Kg), differentfrequencies (10Hz, 25Hz and 40Hz).The wear is a function of normal load, reciprocating frequency, reciprocating duration and the composition of the material. The percentage of aluminum presents in the composite changesbut the other components remain the same.The four types of composites are fabricated by compression molding process having 0%, 10%, 20% and 30% Al. The effect of different parameters such as normal load, reciprocating frequency and percentage of aluminum has been studied. It is observed that the wear and coefficient of friction is influenced by the parameters. The tendency of wear goes on decreasing with the increase of normal load and it is minimum for a composite having 10%aluminum at a normal load of 0.7Kg and then goes on increasing at higher loads for all types of composite due to the adhesive nature of the composite. The coefficient of friction goes on decreasing with increasing normal loads due to the formation of thin film as an effect of heat generation with normal load.

scholarly journals Analysis of Friction in Total Knee Prosthesis during a Standard Gait Cycle

Lubricants ◽  
2021 ◽  
Vol 9 (4) ◽  
pp. 36
Author(s):  
Matúš Ranuša ◽  
Markus A. Wimmer ◽  
Spencer Fullam ◽  
Martin Vrbka ◽  
Ivan Křupka
Keyword(s):  
Total Knee Replacement ◽  
Knee Replacement ◽  
Computational Models ◽  
Gait Cycle ◽  
Knee Prosthesis ◽  
Shear Stresses ◽  
Cobalt Chromium ◽  
Joint Friction ◽  
The Coefficient Of Friction ◽  
Total Knee

Total knee arthroplasty is on the rise worldwide. Despite its success, revision surgeries are also increasing. According to the American Joint Replacement Registry 2020, 3.3% of revision surgeries are due to wear, and 24.2% are due to mechanical loosening. The combination of shear stresses and wear particles occurring at the bone/implant interface can lead to local osteolysis. Although the shear stresses are partially driven by joint friction, relatively little is known about the evolution of the coefficient of friction (CoF) during a gait cycle in total knee replacement. Here we describe the CoF during a gait cycle and investigate its association with kinematics (slide–roll-ratio), applied load, and relative velocity. The artificial knee was simulated by cobalt–chromium condyle on a flat ultra-high-molecular-weight polyethylene (UHMWPE) tibial plateau, lubricated by either water or proteinaceous solution. We found that the CoF is not a constant but fluctuates between the values close to 0 and 0.15. Cross-correlation suggested that this is primarily an effect of the slide–roll ratio and the contact pressure. There was no difference in the CoF between water and proteinaceous solution. Knowledge about the CoF behavior during a gait cycle will help to increase the accuracy of future computational models of total knee replacement.

scholarly journals Tribological Aspects, Optimization and Analysis of Cu-B-CrC Composites Fabricated by Powder Metallurgy

Materials ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4217
Author(s):  
Üsame Ali Usca ◽  
Mahir Uzun ◽  
Mustafa Kuntoğlu ◽  
Serhat Şap ◽  
Khaled Giasin ◽  
...  
Keyword(s):  
Weight Loss ◽  
Wear Rate ◽  
Coefficient Of Friction ◽  
Applied Load ◽  
Practical Significance ◽  
Tribological Characteristics ◽  
M 10 ◽  
Wide Range ◽  
The Coefficient Of Friction ◽  
Four Levels

Tribological properties of engineering components are a key issue due to their effect on the operational performance factors such as wear, surface characteristics, service life and in situ behavior. Thus, for better component quality, process parameters have major importance, especially for metal matrix composites (MMCs), which are a special class of materials used in a wide range of engineering applications including but not limited to structural, automotive and aeronautics. This paper deals with the tribological behavior of Cu-B-CrC composites (Cu-main matrix, B-CrC-reinforcement by 0, 2.5, 5 and 7.5 wt.%). The tribological characteristics investigated in this study are the coefficient of friction, wear rate and weight loss. For this purpose, four levels of sliding distance (1000, 1500, 2000 and 2500 m) and four levels of applied load (10, 15, 20 and 25 N) were used. In addition, two levels of sliding velocity (1 and 1.5 m/s), two levels of sintering time (1 and 2 h) and two sintering temperatures (1000 and 1050 °C) were used. Taguchi’s L16 orthogonal array was used to statistically analyze the aforementioned input parameters and to determine their best levels which give the desired values for the analyzed tribological characteristics. The results were analyzed by statistical analysis, optimization and 3D surface plots. Accordingly, it was determined that the most effective factor for wear rate, weight loss and friction coefficients is the contribution rate. According to signal-to-noise ratios, optimum solutions can be sorted as: the highest levels of parameters except for applied load and reinforcement ratio (2500 m, 10 N, 1.5 m/s, 2 h, 1050 °C and 0 wt.%) for wear rate, certain levels of all parameters (1000 m, 10 N, 1.5 m/s, 2 h, 1050 °C and 2.5 wt.%) for weight loss and 1000 m, 15 N, 1 m/s, 1 h, 1000 °C and 0 wt.% for the coefficient of friction. The comprehensive analysis of findings has practical significance and provides valuable information for a composite material from the production phase to the actual working conditions.

scholarly journals Influence of Beam Power on Young’s Modulus and Friction Coefficient of Ti–Ta Alloys Formed by Electron-Beam Surface Alloying

Metals ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 1246
Author(s):  
Stefan Valkov ◽  
Dimitar Dechev ◽  
Nikolay Ivanov ◽  
Ruslan Bezdushnyi ◽  
Maria Ormanova ◽  
...  
Keyword(s):  
Electron Beam ◽  
Young’S Modulus ◽  
Coefficient Of Friction ◽  
Young's Modulus ◽  
Beam Power ◽  
Surface Alloying ◽  
Surface Alloys ◽  
X Ray ◽  
The Coefficient Of Friction ◽  
Beam Surface

In this study, we present the results of Young’s modulus and coefficient of friction (COF) of Ti–Ta surface alloys formed by electron-beam surface alloying by a scanning electron beam. Ta films were deposited on the top of Ti substrates, and the specimens were then electron-beam surface alloyed, where the beam power was varied from 750 to 1750 W. The structure of the samples was characterized by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and X-ray diffraction (XRD). Young’s modulus was studied by a nanoindentation test. The coefficient of friction was studied by a micromechanical wear experiment. It was found that at 750 W, the Ta film remained undissolved on the top of the Ti, and no alloyed zone was observed. By an increase in the beam power to 1250 and 1750 W, a distinguished alloyed zone is formed, where it is much thicker in the case of 1750 W. The structure of the obtained surface alloys is in the form of double-phase α’and β. In both surface alloys formed by a beam power of 1250 and 1750 W, respectively, Young’s modulus decreases about two times due to different reasons: in the case of alloying by 1250 W, the observed drop is attributed to the larger amount of the β phase, while at 1750 W is it due to the weaker binding forces between the atoms. The results obtained for the COF show that the formation of the Ti–Ta surface alloy on the top of Ti substrate leads to a decrease in the coefficient of friction, where the effect is more pronounced in the case of the formation of Ti–Ta surface alloys by a beam power of 1250 W.

Reducing the Coefficient of Friction for Fast-Absorbing Gut Suture

2009 ◽  
Vol 35 (12) ◽  
pp. 2004 ◽  
Author(s):  
Jonathan Lee Bingham ◽  
Mariah R. Brown ◽  
Julian Ramsey Mellette
Keyword(s):  
Coefficient Of Friction ◽  
The Coefficient Of Friction
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