A Study of the Elastohydrodynamic Problem in Rectangular Elastomeric Seals

1984 ◽  
Vol 106 (4) ◽  
pp. 505-512 ◽  
Author(s):  
E. Prati ◽  
A. Strozzi
Keyword(s):  
Pressure Distribution ◽  
Contact Pressure ◽  
Elastohydrodynamic Lubrication ◽  
Fluid Film ◽  
Hydrodynamic Theory ◽  
Sliding Velocity ◽  
Dry Contact ◽  
Elastomeric Seals ◽  
Film Profile

This paper deals with the study of the elastohydrodynamic lubrication in elastomeric rectangular seals with rounded edges. The photoelastic and the numerical methods are employed in the determination of the dry contact pressure distribution. The existence of two contact pressure peaks near the seal edges is clarified. The influence of the sealed pressure and the sliding velocity on the pressure distribution is examined experimentally. The influence of Poisson’s ratio and constitutive relation on the stress field is studied numerically. The inverse hydrodynamic theory and the numerical method are used in the determination of the fluid film profile. The experimental and numerical fluid film shapes at the inlet are discussed. The influence on the film shape of the sealed pressure is studied experimentally, while the influence of the sliding velocity is examined numerically. The agreement between the experimental and the numerical results for the common cases is satisfactory.

A Note on the Elastohydrodynamic Lubrication of Soft Contacts

1986 ◽  
Vol 200 (3) ◽  
pp. 189-194 ◽  
Author(s):  
C J Hooke
Keyword(s):  
Pressure Distribution ◽  
Transition Zone ◽  
Contact Pressure ◽  
Elastohydrodynamic Lubrication ◽  
Contact Pressure Distribution ◽  
Rigid Cylinder ◽  
Dry Contact ◽  
Highly Loaded

The clearances in highly loaded non-Hertzian contacts can be calculated directly from the dry contact pressure distribution. This note presents a method of extending the analysis into less highly loaded regions. It is shown that the method accurately predicts the clearance over much of the transition zone for Hertzian contacts and its use in a non-Hertzian situation is illustrated using the contact between a rigid cylinder and an elastomer-lined surface as an example.

A Numerical Analysis for the Transient EHL Process of a Cam-Tappet Pair in I. C. Engine

1989 ◽  
Vol 111 (3) ◽  
pp. 413-417 ◽  
Author(s):  
Xiaolan Ai ◽  
Haiqing Yu
Keyword(s):  
Numerical Analysis ◽  
Pressure Distribution ◽  
Numerical Method ◽  
Rotation Angle ◽  
Elastohydrodynamic Lubrication ◽  
Surface Failure ◽  
Lubrication Conditions ◽  
Film Profile

The transient elastohydrodynamic lubrication (EHL) process of cam-tappet pair in I. C. engine is analyzed with a full numerical method. The variations of pressure distribution and film profile as a function of rotation angle of cam shaft provide useful information in evaluating lubrication conditions as well as analyzing failures of contacting surfaces. Results show that the segment in cam contour from φ = 30 to φ = 110 deg is a difficult lubrication range, and surface failure may occur first in this range. This statement was confirmed by preliminary exprimental work conducted in a testing rig.

Quantitative determination of the contact pressure distribution in the hip joint during gait

1999 ◽  
Vol 102 (8) ◽  
pp. 625-631 ◽  
Author(s):  
R. v. Eisenhart-Rothe ◽  
H. Witte ◽  
M. Steinlechner ◽  
M. Müller-Gerbl ◽  
R. Putz ◽  
...  
Keyword(s):  
Quantitative Determination ◽  
Pressure Distribution ◽  
Contact Pressure ◽  
Hip Joint ◽  
Contact Pressure Distribution

Analysis of elastohydrodynamic lubrication in a novel metal-on-metal hip joint replacement

2002 ◽  
Vol 216 (3) ◽  
pp. 185-193 ◽  
Author(s):  
M Jagatia ◽  
Z M Jin
Keyword(s):  
Finite Element ◽  
Film Thickness ◽  
Pressure Distribution ◽  
Contact Pressure ◽  
Elastohydrodynamic Lubrication ◽  
Metal On Metal ◽  
Minimum Film Thickness ◽  
Acetabular Components ◽  
Cobalt Chrome Alloy ◽  
Cobalt Chrome

Elastohydrodynamic lubrication (EHL) analysis was carried out in this study for a novel metal-on-metal hip prosthesis, which consists of a cobalt-chrome alloy femoral head articulating against a cobalt-chrome alloy acetabular insert connected to a titanium fixation shell through a taper. Finite element models were developed to investigate the effect of the pelvic bone and the load on the predicted contact pressure distribution between the two bearing surfaces under dry conditions. The finite element method was used to develop elasticity models for both the femoral and the acetabular components; it was found that the elastic deformation of the acetabular insert was mainly dependent on the load, rather than the detailed pressure distribution. A modified solution methodology was accordingly developed to couple the elasticity models for both the femoral and the acetabular surfaces with the Reynolds equation and to solve these numerically by the finite difference method. It was found that a load increase from 500 to 2500 N had a negligible effect on the predicted maximum contact pressure and the minimum film thickness, due to the relatively flexible and accommodating structure of the acetabular insert. Furthermore, the predicted minimum film thickness was shown to be significantly greater than the simple estimation based on the assumption of semi-infinite solids (mono-block design) using the Hamrock and Dowson formula. The effects of the viscosity of the lubricant and the radial clearance between the femoral and the acetabular components on the predicted lubricating film thickness were investigated under both in vitro simulator testing and in vivo walking conditions.

Investigation of the Effects of Initial Fluid Film Profile on Pumping Ring Operation

1983 ◽  
Vol 105 (4) ◽  
pp. 609-614
Author(s):  
P. J. Smith ◽  
T. G. Keith
Keyword(s):  
Pressure Distribution ◽  
Flow Pattern ◽  
Pronounced Effect ◽  
Fluid Film ◽  
Shaft Seal ◽  
Initial Film ◽  
Film Profile

The effect of the initial fluid film profile on the pumping capacity of a pumping ring shaft seal has been investigated numerically. Linear, concave, convex and compound film shapes were considered. It was found that initial film shape has a pronounced effect on both the amount of fluid pumped and on the character of the flow pattern and pressure distribution within the film.

Pressure Calculation From Experimentally Evaluated Lubricant Thickness Within EHL Contacts

2007 ◽  
Author(s):  
M. Vrbka ◽  
M. Vaverka ◽  
R. Poliscuk ◽  
I. Krupka ◽  
M. Hartl
Keyword(s):  
Film Thickness ◽  
Contact Pressure ◽  
Point Contact ◽  
Elastohydrodynamic Lubrication ◽  
Lubricant Film ◽  
Solution Technique ◽  
Lubricant Film Thickness ◽  
Smooth Contact ◽  
Friction Surfaces

This paper is concerned with elastohydrodynamic lubrication, especially determination of lubricant film thickness and contact pressure within a point contact of friction surfaces of machine parts. A new solution technique for numerical determination of contact pressure is introduced. Direct measurement of contact pressure is very difficult. Hence, input data of lubricant film thickness obtained from the experiment based on colorimetric interferometry are used for calculation of pressure using the inverse elasticity theory. The algorithm is enhanced by convolution in order to increase calculation speed. The approach gives credible results on smooth contact and it is currently extended to enable the study of contact of friction surfaces with dents.

scholarly journals Axial Balance of External Gear Pumps and Motors: Modelling and Discussing the Influence of Elastohydrodynamic Lubrication in the Axial Gap

2015 ◽  
Author(s):  
Massimo Borghi ◽  
Barbara Zardin
Keyword(s):  
Pressure Distribution ◽  
Elastic Deformation ◽  
Numerical Procedure ◽  
Elastohydrodynamic Lubrication ◽  
Viscous Friction ◽  
Operating Conditions ◽  
Internal Surfaces ◽  
External Gear Pumps ◽  
Gear Pumps

This paper focuses on the analysis of hydraulically balanced external gear pumps, in particular on the lubricating gap between the bushes and the gears. This topic is of key importance for the optimization of the machine efficiency because it both influences the mechanical-viscous friction and the volumetric losses. In this paper the intent is to investigate the role of the elastic deformation of the bushes surfaces, to compare the analysis done with rigid and elastic surfaces and finally to correlate the results with the design of the bushes balancing surfaces. A numerical procedure for the determination of the pressure distribution inside the gap bounded by gears sides and the bushes internal surfaces is presented and applied. With respect to past works of the authors, the procedure has been integrated taking into account the elastic deformation of the internal surfaces of the bushes and the variation of the dynamic viscosity of fluid, two well recognized phenomena that can play a key role on the determination of the bushes behaviour and lubricating gap pressure distribution. It is shown that, when the design of the bushes rear surfaces determines a strong balancing thrust, the bushes themselves need to tilt strongly with respect to the gears to generate an opportune widening thrust to avoiding contact with the gears. Useful suggestions for the bushes balancing surface design may be drawn from the analysis of the balancing maps reported in the paper, which illustrate the widening thrust magnitude and position in both the pure hydrodynamic and elasto-hydrodynamic cases, for different tilted positions and operating conditions.

The influence of articular surface incongruity on lubrication and contact pressure distribution of loaded synovial joints

1998 ◽  
Vol 212 (1) ◽  
pp. 11-22 ◽  
Author(s):  
M Hlaváček ◽  
D Vokoun
Keyword(s):  
Film Thickness ◽  
Pressure Distribution ◽  
Contact Pressure ◽  
Subchondral Bone ◽  
Fluid Film ◽  
Synovial Joint ◽  
Contact Pressure Distribution ◽  
Surface Geometry ◽  
Articular Surfaces ◽  
Fluid Film Thickness

In the model intended for short-term loading (such as during the walking cycle) of a human synovial joint in the lower extremities, cartilage lubricated by Newtonian synovial fluid is considered to be incompressible elastic and subchondral bone is considered to be rigid. The model is non-diffusional, i.e. no interstitial fluid flow occurs across the articular surfaces. A simple plane strain case of the human ankle joint is considered. For high steady loading applied in the centre of the stationary tibial arc and for steady sliding of the talar arc, this model shows that individual physiological variations in the geometry of the articular surfaces have only a small effect on the contact stress distribution and the fluid film thickness. If this load is applied eccentrically in the tibial arc, the contact pressure distribution varies more with surface geometry, but the minimum fluid film thickness differs little from that for symmetric loading. The maximum contact pressure is placed eccentrically in this case, but its value is changed only little when compared to the central loading of the same value. In order to explain different distribution patterns of subchondral bone mineralization, it is anticipated that the total load peaks of periodic time-dependent loads are transmitted centrally in some incongruent joints and eccentrically in others.

Rim Slip and Bead Fitment of Tires: Analysis and Design2

2006 ◽  
Vol 34 (1) ◽  
pp. 38-63 ◽  
Author(s):  
C. Lee
Keyword(s):  
Pressure Distribution ◽  
Contact Pressure ◽  
Frictional Torque ◽  
Finite Element Analyses ◽  
Inflation Pressure ◽  
Contact Pressure Distribution ◽  
Design Modification ◽  
Iterative Design ◽  
Slip Resistance ◽  
Braking Torque

Abstract A tire slips circumferentially on the rim when subjected to a driving or braking torque greater than the maximum tire-rim frictional torque. The balance of the tire-rim assembly achieved with weight attachment at certain circumferential locations in tire mounting is then lost, and vibration or adverse effects on handling may result when the tire is rolled. Bead fitment refers to the fit between a tire and its rim, and in particular, to whether a gap exists between the two. Rim slip resistance, or the maximum tire-rim frictional torque, is the integral of the product of contact pressure, friction coefficient, and the distance to the wheel center over the entire tire-rim interface. Analytical solutions and finite element analyses were used to study the dependence of the contact pressure distribution on tire design and operating attributes such as mold ring profile, bead bundle construction and diameter, and inflation pressure, etc. The tire-rim contact pressure distribution consists of two parts. The pressure on the ledge and the flange, respectively, comes primarily from tire-rim interference and inflation. Relative contributions of the two to the total rim slip resistance vary with tire types, depending on the magnitudes of ledge interference and inflation pressure. Based on the analyses, general guidelines are established for bead design modification to improve rim slip resistance and mountability, and to reduce the sensitivity to manufacturing variability. An iterative design and analysis procedure is also developed to improve bead fitment.

One-Dimensional Contact Pressure Distribution of Radial Tires in Motion

1995 ◽  
Vol 23 (2) ◽  
pp. 116-135 ◽  
Author(s):  
H. Shiobara ◽  
T. Akasaka ◽  
S. Kagami ◽  
S. Tsutsumi
Keyword(s):  
Pressure Distribution ◽  
Contact Pressure ◽  
Experimental Studies ◽  
Rolling Resistance ◽  
Leading Edge ◽  
Forward Direction ◽  
Contact Pressure Distribution ◽  
Support Ring ◽  
One Dimensional ◽  
Lowered Pressure

Abstract The contact pressure distribution and the rolling resistance of a running radial tire under load are fundamental properties of the tire construction, important to the steering performance of automobiles, as is well known. Many theoretical and experimental studies have been previously published on these tire properties. However, the relationships between tire performances in service and tire structural properties have not been clarified sufficiently due to analytical and experimental difficulties. In this paper, establishing a spring support ring model made of a composite belt ring and a Voigt type viscoelastic spring system of the sidewall and the tread rubber, we analyze the one-dimensional contact pressure distribution of a running tire at speeds of up to 60 km/h. The predicted distribution of the contact pressure under appropriate values of damping coefficients of rubber is shown to be in good agreement with experimental results. It is confirmed by this study that increasing velocity causes the pressure to rise at the leading edge of the contact patch, accompanied by the lowered pressure at the trailing edge, and further a slight movement of the contact area in the forward direction.

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