Influence of Material Anisotropy and Friction on Ring Deformation

2002 ◽  
Vol 124 (3) ◽  
pp. 637-644 ◽  
Author(s):  
Han Han
Keyword(s):  
Coefficient Of Friction ◽  
Normal Pressure ◽  
Flow Rule ◽  
Material Anisotropy ◽  
Anisotropic Ring ◽  
Frictional Shear Stress ◽  
The Coefficient Of Friction ◽  
Von Mises ◽  
Estimated Error ◽  
Ring Deformation

The influence of material anisotropy and friction on ring deformation has been examined in relation to the distribution of normal pressure and frictional shear stress, deformed ring shapes, and estimated errors in the coefficient of friction. Based on the flow rule associated with von Mises’ and Hill’s yield criteria, the analyses have been carried out with the finite element method (FEM) for three cases, namely, (1) an anisotropic ring oriented 90 deg to the axis of rotational symmetrical anisotropy under uniform coefficient of friction; (2) an isotropic ring under frictional anisotropy condition; and (3) an anisotropic ring oriented 0 deg to the axis of rotational symmetrical anisotropy under uniform coefficient of friction. In the first two cases, the results show that the influence of anisotropy on ring deformation is quite similar to that obtained by changing the frictional condition. Therefore, in the third case, if the anisotropic behavior is mistakenly attributed to friction, the possible estimated error for the coefficient of friction can be as high as 80 percent for a pronounced anisotropic material. Deformed ring shapes have been verified in experiments using the extruded annealed aluminum alloy AA6082 (Al-Si1Mg0.9Mn0.1).

The Data Processing Technique of Metallic Sheet Friction Coefficient Determination

2012 ◽  
Vol 184-185 ◽  
pp. 688-691
Author(s):  
Huan Xue ◽  
Rong Feng Li ◽  
Hong Chuan Zhu
Keyword(s):  
Data Processing ◽  
Coefficient Of Friction ◽  
Normal Pressure ◽  
Processing Technique ◽  
Test Results ◽  
Friction Zone ◽  
Data Processing Method ◽  
The Coefficient Of Friction ◽  
Processing Techniques ◽  
Metallic Sheet

The definition and research background of friction is introduced. The reason of generation of friction is analyzed, the importance of the coefficient of friction test in sheet metal forming field is indicated. The testing principle of coefficient of friction on metallic sheet is presented. The basic data processing method of the test is described. Two important data processing techniques which will obviously effects the test results, including effective friction zone and normal pressure have been carefully studied. The comparison result shows these techniques can effectively enhance the testing stability and precision.

Dependence of the Coefficient of Friction on the Sliding Conditions in the High Velocity Range

1999 ◽  
Vol 121 (1) ◽  
pp. 35-41 ◽  
Author(s):  
A. Molinari ◽  
Y. Estrin ◽  
S. Mercier
Keyword(s):  
Coefficient Of Friction ◽  
High Velocity ◽  
Numerical Solutions ◽  
Constitutive Relations ◽  
Shear Banding ◽  
Normal Pressure ◽  
Adiabatic Shear ◽  
Velocity Range ◽  
Adiabatic Shear Banding ◽  
The Coefficient Of Friction

The velocity, normal pressure, and slider size dependence of the coefficient of dry friction of metals in the range of high sliding velocities (V ≥ 1 m/s) is investigated theoretically. Failure of the adhesive junctions by adiabatic shear banding is considered as the underlying process. The concept of asperity shearing by the adiabatic shear banding mechanism represents a new approach to unlubricated high velocity friction. Analytical solutions of a coupled thermomechanical problem are given for two constitutive relations. Numerical solutions for steel-on-steel friction showing a decrease of the coefficient of friction with the sliding velocity for different normal pressures are presented. The model is considered to be adequate in the velocity range of 1–10 m/s where friction enhanced oxidation or surface melting are believed not to interfere with the asperity shearing process.

scholarly journals A Contact Characteristic of Roller Bearing with Palm Oil-based Grease Lubrication

2021 ◽  
Vol 89 (2) ◽  
pp. 139-149
Author(s):  
Yap Jun Heng ◽  
Nurul Farhana Mohd Yusof ◽  
Lee Ann Yen ◽  
Shazlina Abd Hamid ◽  
Nurul Nadzirah Mohd Yusof
Keyword(s):  
Finite Element ◽  
Coefficient Of Friction ◽  
Palm Oil ◽  
Frictional Contact ◽  
Roller Bearing ◽  
Rolling Contact ◽  
Von Mises Stress ◽  
The Coefficient Of Friction ◽  
Contact Characteristic ◽  
Von Mises

Grease lubricants are widely used in rolling contact applications to reduce friction between two rolling surfaces. Improper lubrication may cause high contact stress and deformation to the bearings and lead to machine failure The purpose of this study is to investigate the coefficient of friction produced by newly developed palm oil-based grease and to investigate the contact characteristics in lubricated roller bearings. In this work, the coefficient of friction of new greases was evaluated experimentally and the values were compared with the conventional mineral oil-based grease to investigate the friction performance. The friction test was performed using a four-ball tester. The finite element model was developed based on the roller bearing geometry and the simulation was carried out the evaluate the contact characteristic. The experimental result shows that the palm oil grease formulation A had the least coefficient of friction, followed by palm oil grease formulation B, mineral grease and food grade grease. This indicates that palm oil-based grease has the potential to be applied in rolling contact applications due to low friction characteristics. Finite element analysis shows that the maximum von Mises stress and total deformation for frictional contact are higher than the frictionless contact. For the frictional contact analysis with various lubricant COF, similar values were obtained with von Mises stress at 400.69 MPa and 3.4033×10-4 mm deformation. The finding shows that the small difference in grease COF did not affect the rolling contact. The finding also shows that the newly developed biodegradable grease has a similar performance in terms of rolling contact friction and contact characteristic in a condition that the bearing is operating in normal condition.

scholarly journals MODELLING OF A GLASS GATHERER ROBOT'S ARM WITH A FRICTIONAL DAMPER

2018 ◽  
Vol 18 (4) ◽  
pp. 127-140
Author(s):  
Marek STEMBALSKI ◽  
Pawel PRES ◽  
Waclaw SKOCZYNSKI ◽  
Paweł TUREK
Keyword(s):  
Numerical Model ◽  
Finite Elements ◽  
Coefficient Of Friction ◽  
Normal Pressure ◽  
Operating Parameters ◽  
Sliding Velocity ◽  
Friction Damper ◽  
Damping Decrement ◽  
The Coefficient Of Friction ◽  
Contact Surfaces

A numerical model of a friction damper used for damping vibration in glass gatherer robots was described. The damper with a lance was modelled using finite elements. Primary natural frequency of the system was determined. Numerical calculations were performed to determine the best operating parameters of the damper for excitations using a impulse of a force. Results of the damping decrement calculations for the friction damper model with a constant coefficient of friction and for the model, in which the coefficient of friction varied depending on the sliding velocity and the normal pressure occurring at the contact surfaces of the damper’s friction rings, were presented. Based on numerical simulations, the values of relative displacements between the damper’s friction rings were also determined.

scholarly journals Effect of friction in the interaction of an anisotropic strip with a rigid base

2020 ◽  
Vol 16 (2) ◽  
pp. 122-130
Author(s):  
Sergey G. Kudryavtsev ◽  
Julia M. Buldakova
Keyword(s):  
Coefficient Of Friction ◽  
Integral Transform ◽  
Anisotropic Body ◽  
Normal Pressure ◽  
Theory Of Elasticity ◽  
Rigid Base ◽  
Surface Load ◽  
Normal Surface ◽  
Concentrated Force ◽  
The Coefficient Of Friction

Relevance. Different models of contact between bodies are used in determining the stressed and deformed state in the strip lying on the base. It is necessary to evaluate the qualitative and quantitative nature of the change in stress in the strip depending on the coupling of the strip and base. The aim of the work - to analyze the effect of the coefficient of friction on the value of stresses in an anisotropic band when interacting with a rigid base. Methods. The solution is based on the equations of the plane problem of the theory of elasticity of an anisotropic body under the conditions that the band is closely adjacent to the base and the tangent force on the contact plane is proportional to the normal pressure. Displacements and stresses at any point of the strip are written in the form of the method of initial functions through the functions of displacements and forces on the lower plane, which depend on the nature of the load applied on the upper plane and the conditions of contact between the strip and the base. After the transformations, the calculation formulas for displacements and stresses are expressed using the Fourier integral transform through the normal surface load in the form of improper integrals. Results. Formulas for determining displacements and stresses are obtained for the variant of loading a strip with a concentrated force. These formulas are used to construct influence functions for the problem of equilibrium of an anisotropic strip lying on a rigid base, taking into account friction. Graphs of the effect of the coefficient of friction and the direction of the anisotropy axes of the material on the stress state of the strip are presented. The results of stress calculation are compared using anisotropic and isotropic models.

Application of Variable Coefficient of Friction and Wear to Block Brakes and Clutches

1966 ◽  
Vol 8 (4) ◽  
pp. 406-418 ◽  
Author(s):  
J. C. Heap
Keyword(s):  
Coefficient Of Friction ◽  
Variable Coefficient ◽  
Friction And Wear ◽  
Normal Pressure ◽  
Radial Force ◽  
Uniform Pressure ◽  
Mean Pressure ◽  
The Coefficient Of Friction ◽  
Basic Equations ◽  
Tangential Friction

A mathematical analysis correlates the coefficient of friction and the wear rate in terms of pressure, velocity, area, temperature, and so forth, over discrete experimental data ranges. The basic equations of total torque, total radial force, total tangential friction force, and ideal pivot for block brakes and clutches having the coefficient of friction initially a function of normal pressure and relative rubbing velocity have been developed for dry or slightly lubricated surfaces. Three conditions are analysed: uniform wear having the coefficient of friction a function of pressure and velocity, uniform wear having the coefficient of friction a function of velocity and mean pressure, and uniform pressure having the coefficient of friction a function of velocity.

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 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.

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