An Experimental Investigation of Stick-Slip in Hydrostatic Extrusion Using Wax to Simulate Metals

1976 ◽  
Vol 98 (3) ◽  
pp. 795-799 ◽  
Author(s):  
D. Egerton ◽  
W. B. Rice
Keyword(s):  
Experimental Investigation ◽  
Pressure Pulse ◽  
Pressure Fluctuations ◽  
Hydrostatic Extrusion ◽  
Fluid Film ◽  
Stick Slip ◽  
Film Lubrication ◽  
Fluid Film Lubrication

This paper describes an experimental investigation undertaken to check the explanation advanced by Rice and Iyengar for the violent pressure fluctuations which they observed during hydrostatic extrusion of wax. The results support the explanation advanced by Rice and Iyengar, confirming their suspicion that extrusion actually stops during the period of violent pressure fluctuations and reinforcing their contention that for short periods of time during each pressure pulse the velocity necessary for initiation of fluid film lubrication is exceeded, causing fluid in the form of a film to be transported into the die during those periods.

Mathematical Analysis of the Motion of Fluid in Between Ceramic-on-Ceramic Total Joint Arthroplasty Bearing Surfaces

2014 ◽  
Author(s):  
Manish Paliwal ◽  
Thulsi Wickramasinghe
Keyword(s):  
Femoral Head ◽  
Articular Surface ◽  
Fluid Film ◽  
Initial Contact ◽  
Fluid Viscosity ◽  
Stick Slip ◽  
Start Up ◽  
Film Lubrication ◽  
Fluid Film Lubrication ◽  
Ceramic On Ceramic

Friction-induced squeaking has been reported in 1–20% of patients who have a ceramic on ceramic total hip replacement, which is a subject of annoyance. Friction induced stick-slip phenomenon is the driving force behind squeaking. Stick-slip occurs when the film lubrication is broken. Fluid film lubrication is a function of sliding speed, lubricating fluid viscosity, bearing roughness, clearance, and contact pressure. A breakdown of fluid film lubrication may result from edge loading, presence of third bodies (wear particles) during articulation, damage to the articular surface (increased roughness), mismatched bearing diameters, etc. In the present study, influence of variation in relative densities of the biofluid and femoral head is mathematically investigated when the spheres are initially subjected to an impulse (start-up condition: initial contact to pre-swing phase of the gait cycle). The parametric analysis also looks at the influence of initial impulse speed, and time of approach of the femoral head to the outer shell.

Paper 3: Recent Developments in Fluid Film Lubrication Theory

1967 ◽  
Vol 182 (1) ◽  
pp. 36-50 ◽  
Author(s):  
T. Lloyd ◽  
H. McCallion
Keyword(s):  
Finite Difference ◽  
High Speed ◽  
Lubrication Theory ◽  
Fluid Film ◽  
Special Topic ◽  
Finite Difference Schemes ◽  
Great Activity ◽  
Wide Range ◽  
Film Lubrication ◽  
Fluid Film Lubrication

Developments in high-speed electronic computers have greatly influenced the progress in fluid film lubrication over the past ten years. Static and dynamic oil film parameters have been computed for a wide range of finite geometries, for hydrostatic and hydrodynamic bearings lubricated by compressible and incompressible lubricants. These are either sufficient in themselves or else act as a yardstick against which approximate formulas may be tested. Much use has been made of iterative finite difference schemes, which are particularly well suited to digital computers, and these methods are now more fully understood. Other methods of solution include direct inversion of finite difference matrices and solution by expression of the pressure by some infinite series, a finite number of terms of which give adequate representation. Besides the increase in design data available, there has been substantial progress through a re-examination of the effects of modifying some of the assumptions inherent in most of the available solutions of the Reynolds equation. These include the assumption of constant lubricant viscosity, of rigid surfaces and of laminar flow. Major progress has been witnessed in two fields. The interaction of the lubricant film with elastic boundaries has been shown to be of prime importance in highly loaded contacts such as gears. This has led to the development of the special topic of elastohydrodynamic lubrication theory. The applicability of gas bearings in such growing industries as computers, space vehicles and nuclear reactors has resulted in great activity and progress in this field.

The breakdown of fluid film lubrication in elastic-isoviscous point contacts

Wear ◽  
1980 ◽  
Vol 63 (1) ◽  
pp. 25-40 ◽  
Author(s):  
J.B. Medley ◽  
A.B. Strong ◽  
R.M. Pilliar ◽  
E.W. Wong
Keyword(s):  
Fluid Film ◽  
Point Contacts ◽  
Film Lubrication ◽  
Fluid Film Lubrication

scholarly journals Mixed and Fluid Film Lubrication Characteristics of Worn Journal Bearings

2012 ◽  
Vol 2012 ◽  
pp. 1-7 ◽  
Author(s):  
Toshiharu Kazama ◽  
Yukihito Narita
Keyword(s):  
Frictional Coefficient ◽  
Journal Bearings ◽  
Mixed Lubrication ◽  
Operating Conditions ◽  
Fluid Film ◽  
Asperity Contact ◽  
Lubrication Regimes ◽  
Lubrication Characteristics ◽  
Film Lubrication ◽  
Fluid Film Lubrication

The mixed and fluid film lubrication characteristics of plain journal bearings with shape changed by wear are numerically examined. A mixed lubrication model that employs both of the asperity-contact mechanism proposed by Greenwood and Williamson and the average flow model proposed by Patir and Cheng includes the effects of adsorbed film and elastic deformation is applied. Considering roughness interaction, the effects of the dent depth and operating conditions on the loci of the journal center, the asperity-contact and hydrodynamic fluid pressures, friction, and leakage are discussed. The following conclusions are drawn. In the mixed lubrication regime, the dent of the bearing noticeably influences the contact and fluid pressures. For smaller dents, the contact pressure and frictional coefficient reduce. In mixed and fluid film lubrication regimes, the pressure and coefficient increase for larger dents. Furthermore, as the dent increases and the Sommerfeld number decreases, the flow rate continuously increases.

Optimum Design of Hydrostatic Spherical Bearings in Fluid Film Lubrication

2000 ◽  
Vol 122 (4) ◽  
pp. 866-869 ◽  
Author(s):  
Toshiharu Kazama
Keyword(s):  
Optimum Design ◽  
Analytical Solutions ◽  
Power Loss ◽  
Fluid Film ◽  
Optimal Size ◽  
Minimum Power ◽  
Maximum Stiffness ◽  
The Difference ◽  
Film Lubrication ◽  
Fluid Film Lubrication

The optimum design of hydrostatic spherical bearings in fluid film lubrication is examined theoretically. The analytical solutions are derived for both fitted and clearance types of bearings with capillary and orifice restrictors. The optimal size based on the minimum power loss and the maximum stiffness is presented, and the difference between two types of bearings is discussed. [S0742-4787(00)02204-9]

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