Experimental Validation of the Simulated Steady-State Behavior of Porous Journal Bearings1

2016 ◽  
Vol 138 (3) ◽  
Author(s):  
Ioana Adina Neacşu ◽  
Bernhard Scheichl ◽  
Georg Vorlaufer ◽  
Stefan J. Eder ◽  
Friedrich Franek ◽  
...  
Keyword(s):  
Experimental Validation ◽  
Stribeck Curve ◽  
Interpolation Scheme ◽  
Eccentricity Ratio ◽  
Main Interest ◽  
State Behavior ◽  
Frictional Behavior ◽  
The Coefficient Of Friction ◽  
Numerical Interpolation ◽  
Lubricant Viscosity

This study deals with a comparison between new experiments on the frictional behavior of porous journal bearings and its prediction by previous numerical simulations. The tests were carried out on bearings lubricated with polyalphaolefin (PAO)-based oils of distinct viscosities. The theoretical model underlying the simulations includes the effects of cavitation by vaporization and accounts for the sinter flow by virtue of Darcy's law. The effective eccentricity ratio corresponding to the experimentally imposed load is estimated by an accurate numerical interpolation scheme. The comparison focuses on the hydrodynamic branches of the Stribeck curve by dimensional analysis (DA), where the variations of the lubricant viscosity with temperature are of main interest. The numerically calculated values of the coefficient of friction are found to reproduce the experimentally obtained ones satisfactorily well in terms of overall trends; yet, the former lie predominantly below the measured ones, which results in a low-positive correlation between the two.

Tribological Behaviour of GFR Polymer Composites

2005 ◽  
Author(s):  
J. Quintelier ◽  
P. Samyn ◽  
P. De Baets ◽  
J. Degrieck
Keyword(s):  
Polymer Matrix Composites ◽  
Normal Load ◽  
Thin Polymer Film ◽  
Matrix Composites ◽  
Tribological Behaviour ◽  
Frictional Behavior ◽  
Glass Fiber Reinforced ◽  
Thin Polymer ◽  
Pin On Disc ◽  
The Coefficient Of Friction

On a Pin-on-Disc test rig with composite disc and steel pin tribological experiments were done on pultruded glass fiber reinforced polymer matrix composites plates. The wear and frictional behavior strongly depends on the structure. Also the normal load plays an important role in the frictional behavior, which is of greater importance than the speed. The formation of a thin polymer film onto the wear track results in a lowering of the coefficient of friction with 20%.

Tribometer for Dry Friction Measurement

1999 ◽  
Author(s):  
Marc Brandl ◽  
Friedrich Pfeiffer
Keyword(s):  
Coefficient Of Friction ◽  
Dry Friction ◽  
Stribeck Curve ◽  
Body System ◽  
Friction Measurement ◽  
Detailed Model ◽  
The Coefficient Of Friction ◽  
Simulation Results ◽  
Multi Body

Abstract This paper deals with the measurement of dry friction. A tribometer was developed in order to identify both the sticking and the sliding coefficient of friction. The aim was to determine the so called Stribeck-curve of any material in contact. The design of the plant is presented. Avoiding errors in recalculating the coefficient of friction, a detailed model of the plant as a multi body system with motor feedback was generated. Advantages of the tribometer are shown in simulations. Some results of measurements in comparison with simulation results are presented.

scholarly journals Study on Tribological Properties and Mechanisms of Different Morphology WS2 as Lubricant Additives

Materials ◽  
2020 ◽  
Vol 13 (7) ◽  
pp. 1522 ◽  
Author(s):  
Ningning Hu ◽  
Xiuheng Zhang ◽  
Xianghui Wang ◽  
Na Wu ◽  
Songquan Wang
Keyword(s):  
Wear Resistance ◽  
Optimum Condition ◽  
Lubricating Oil ◽  
Stribeck Curve ◽  
Extreme Pressure ◽  
Friction Process ◽  
Wide Range ◽  
The Coefficient Of Friction ◽  
The Relationship ◽  
Better Than

In the present work, the relationship curve of the coefficient of friction (COF) with varying loads of different morphology WS2 lubricating additives in the friction process at various sliding speeds was studied. On this basis, wear marks and elements on the wear surfaces after friction were analyzed, and then the anti-wear and mechanism effects of WS2 of different forms in the lubrication process were discussed. Meanwhile, the Stribeck curve was used to study the lubrication state of the lubricating oil in the friction process. It was revealed that the COF of lubricating oil containing lamellar WS2 decreased by 29.35% at optimum condition and the minimum COF was concentrated at around 100 N. The COF of lubricating oil containing spherical WS2 decreased by 30.24% and the minimum coefficient was concentrated at 120 N. The extreme pressure property of spherical WS2 was better than that of lamellar WS2, and the wear resistance of spherical WS2 was more stable when the load was over 80 N. The different morphology of WS2 additives can play anti-wear and anti-friction roles within a wide range of sliding speeds.

scholarly journals On the Dependence of Rheology of Hyaluronic Acid Solutions and Frictional Behavior of Articular Cartilage

Materials ◽  
2020 ◽  
Vol 13 (11) ◽  
pp. 2659 ◽  
Author(s):  
David Rebenda ◽  
Martin Vrbka ◽  
Pavel Čípek ◽  
Evgeniy Toropitsyn ◽  
David Nečas ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Hyaluronic Acid ◽  
Articular Cartilage ◽  
Rheological Properties ◽  
Optical Glass ◽  
Clinical Results ◽  
Frictional Behavior ◽  
Molecular Weights ◽  
The Coefficient Of Friction ◽  
Contact Couple

Hyaluronic acid (HA) injections represent one of the most common methods for the treatment of osteoarthritis. However, the clinical results of this method are unambiguous mainly because the mechanism of action has not been clearly clarified yet. Viscosupplementation consists, inter alia, of the improvement of synovial fluid rheological properties by injected solution. The present paper deals with the effect of HA molecular weight on the rheological properties of its solutions and also on friction in the articular cartilage model. Viscosity and viscoelastic properties of HA solutions were analyzed with a rotational rheometer in a cone–plate and plate–plate configuration. In total, four HA solutions with molecular weights between 77 kDa and 2010 kDa were tested. The frictional measurements were realized on a commercial tribometer Bruker UMT TriboLab, while the coefficient of friction (CoF) dependency on time was measured. The contact couple consisted of the articular cartilage pin and the plate made from optical glass. The contact was fully flooded with tested HA solutions. Results showed a strong dependency between HA molecular weight and its rheological properties. However, no clear dependence between HA molecular weight and CoF was revealed from the frictional measurements. This study presents new insight into the dependence between rheological and frictional behavior of the articular cartilage, while such an extensive investigation has not been presented before.

On the Dynamics of a Rotary Compressor: Part 2 — Experimental Validation and Sensitivity Analysis

1993 ◽  
Author(s):  
Sisir K. Padhy
Keyword(s):  
Experimental Validation ◽  
Sensitivity Study ◽  
Rotary Compressor ◽  
Dynamics Model ◽  
The Coefficient Of Friction ◽  
The Moment ◽  
Discharge Pressure ◽  
Roller Radius ◽  
Theoretical Results ◽  
Good Agreement

Abstract This paper describes the experimental validation of the rotary compressor dynamics model [1]. Roller velocity is measured using video technology and a very good agreement is found with the theoretical results. A sensitivity study using different variables that affect the compressor dynamics is also carried out. It is found that the coefficient of friction at the vane and roller plays an important role in roller velocity. The dynamics of roller is influenced by the clearances, the roller radius, the vane radius, eccentricity of the shaft, the frictional behavior between the roller ends and the bearing plates, the discharge pressure of the compressor as well as the moment of inertia of roller.

The Full Journal Bearing

1949 ◽  
Vol 161 (1) ◽  
pp. 59-72 ◽  
Author(s):  
A. Cameron ◽  
W. L. Wood
Keyword(s):  
Boundary Conditions ◽  
Coefficient Of Friction ◽  
Journal Bearing ◽  
Complete Solution ◽  
Radial Clearance ◽  
Eccentricity Ratio ◽  
Relaxation Methods ◽  
The Coefficient Of Friction ◽  
Final Answer ◽  
Detailed Application

The basic mathematics of the full journal bearing have been known since 1904 when Sommerfeld‡ made the complete solution, for the infinite journal, of Reynolds theory of 1886. The detailed application of the theory has not been possible owing to the uncertainty in the choice of boundary conditions. In this paper the Reynolds condition that p = 0 at θ = 0 and p = ∂ p/∂θ = 0 at θ = π + α is shown to follow for the infinite bearing from a consideration of continuity of flow and, equally important, from the shaft stability condition, first put forward by Swift in 1933. It is claimed that this is the final answer to the question of correct boundary conditions. The Reynolds equation for the infinitely wide bearing was solved using these conditions. Assuming the viscosity is constant all round the bearing, the coefficient of friction-load criterion curve has the same slope as experimentally determined curves. The Mathematics Division, N.P.L., computed, by Southwell's relaxation methods (1946), the figures for finite bearings of diameter length ratios of 4, 2, and 1. The theoretical figures for eccentricity ratio-load criterion are satisfactorily compared with some of Nücker's experimental results, and the coefficient of friction, load criterion, figures explain the apparent intercept found by McKee and McKee. A diagram is given allowing the eccentricity ratio c, to be obtained from the load criterion for any bearing of diameter/length ratio from 0 to 4, and this enables the minimum film thickness, which equals (1 — c) x radial clearance, to be calculated.

Multiscale Modeling of Frictional Behavior of Highly-Ordered Carbon Nanotube/Ceramic Nanocomposites

2006 ◽  
Vol 978 ◽  
Author(s):  
Zhenhai Xia ◽  
William A Curtin ◽  
Pradeep Guduru
Keyword(s):  
Carbon Nanotube ◽  
Coefficient Of Friction ◽  
Md Simulation ◽  
Interaction Force ◽  
Thick Wall ◽  
Low Friction ◽  
Frictional Behavior ◽  
The Coefficient Of Friction ◽  
Cnt Arrays ◽  
Ceramic Nanocomposites

AbstractMicromechanics model incorporating with molecular dynamics (MD) simulation is developed to simulate the frictional behavior of carbon nanotube (CNT) arrays in ceramic nanocomposites. MD model is used to compute the interaction force and simulate failure mechanisms of individual nanotube at atomic length scale. The force and deformation calculated from MD simulation are passed to the continuum model to simulate the interaction between nanotube arrays and AFM tips. The coefficient of friction is determined at different load levels. The simulation shows that the low friction in the thick-wall CNT systems occurs because the stiffer CNTs are more resistant to collapse under the applied loads. The predictions for the coefficient of friction are consistent with nanoscale tests.

scholarly journals Effects of a moving X-line in a time-dependent reconnection model

2007 ◽  
Vol 25 (1) ◽  
pp. 293-302 ◽  
Author(s):  
S. A. Kiehas ◽  
V. S. Semenov ◽  
I. V. Kubyshkin ◽  
Yu. V. Tolstykh ◽  
T. Penz ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Neutral Line ◽  
Time Dependent ◽  
Plasma Acceleration ◽  
Main Interest ◽  
State Behavior ◽  
Magnetic Field Topology ◽  
Magnetotail Reconnection ◽  
The Magnetic Field ◽  
Reconnection Model

Abstract. In the frame of magnetized plasmas, reconnection appears as an essential process for the description of plasma acceleration and changing magnetic field topology. Under the variety of reconnection regions in our solar system, we focus our research onto the Earth's magnetotail. Under certain conditions a Near Earth Neutral Line (NENL) is free to evolve in the current sheet of the magnetotail. Reconnection in this region leads to the formation of Earth- and tailward propagating plasma bulges, which can be detected by the Cluster or Geotail spacecraft. Observations give rise to the assumption that the evolved reconnection line does not provide a steady state behavior, but is propagating towards the tail (e.g., Baker et al., 2002). Based on a time-dependent variant of the Petschek model of magnetic reconnection, we present a method that includes an X-line motion and discuss the effects of such a motion. We focus our main interest on the shock structure and the magnetic field behavior, both for the switch-on and the switch-off phase.

scholarly journals On the Transitions in the Lubrication of Concentrated Contacts

1995 ◽  
Vol 117 (2) ◽  
pp. 250-254 ◽  
Author(s):  
D. J. Schipper ◽  
A. W. J. de Gee
Keyword(s):  
Solid State ◽  
Liquid State ◽  
Flow Diagram ◽  
State Behavior ◽  
Operational Conditions ◽  
Frictional Behavior ◽  
Lubrication Mode ◽  
State Regime ◽  
Film Lubrication

Friction experiments on lubricated concentrated contracts were performed to study; (a) the transitions between the different lubrication modes when operating in the lubricants liquid-state regime and (b) the frictional behavior of these contacts, under conditions of full-film lubrication, taking into account the lubricants liquid-state and solid-state behavior. On the basis of these results a flow diagram is presented for lubricated concentrated contacts, from which the lubrication mode as well as the frictional behavior can be obtained as a function of the operational conditions, under which these contacts are functioning.

scholarly journals Study on friction behavior at the interface between prosthetic socket and liner

2021 ◽  
Vol 23 (1) ◽  
Author(s):  
Jingyang Xie ◽  
Xidong Liu ◽  
Jianhua Tang ◽  
Xi Li ◽  
Wei Li
Keyword(s):  
Energy Dissipation ◽  
Coefficient Of Friction ◽  
Temperature Increase ◽  
Friction Behavior ◽  
Friction Characteristics ◽  
Frictional Behavior ◽  
Prosthetic Socket ◽  
The Coefficient Of Friction ◽  
3D Printed ◽  
Frictional Energy Dissipation

Purpose: The friction characteristics at the interface between prosthetic socket and liner have an important influence on the walking function and wearing comfort of amputees. The frictional behavior at the prosthetic socket/liner interface can provide theoretical guidance for the design and selection of prosthetic materials. So it is of great significance to study the friction behavior at prosthetic socket/liner interface. Methods: The surface roughnesses of the prosthetic socket and liner materials were measured by a laser confocal microscope. The frictional behavior at the prosthetic socket/liner interface was studied on a UMT TriboLab Tribometer by simulating the reciprocating sliding contact mode. An infrared camera was used to take thermal images and then calculated the temperature increase at the socket/liner interface. Results: The coefficient of friction of the silicon rubber fabric are significantly smaller than that of the foam liner materials. The frictional energy dissipation at the liner/acrylic socket interface is the smallest, while it is greater for 3D-printed socket materials. Meanwhile, the temperature increase has a positive correlation to the coefficient of friction and frictional energy dissipation. Conclusions: The three kinds of 3D-printed materials with high surface roughness have higher interface coefficient of friction and energy dissipation than acrylic material. The stiffness and energy consumption play an important role in the interface friction characteristics of the prosthetic liner materials. The appropriate coefficient of friction at the surface between prosthetic socket and liner is essential. A type of the reinforcement fiber has influence on the friction behavior of the 3D-printed reinforced nylon.

Sign in / Sign up

Export Citation Format

Share Document