Elastohydrodynamic Film Collapse During Rapid Deceleration. Part II—Theoretical Analysis and Comparison of Theory and Experiment

2000 ◽  
Vol 123 (2) ◽  
pp. 262-267 ◽  
Author(s):  
R. P. Glovnea ◽  
H. A. Spikes
Keyword(s):  
Theoretical Model ◽  
Analytical Solution ◽  
Theoretical Analysis ◽  
Film Thickness ◽  
Elastohydrodynamic Lubrication ◽  
Experimental Results ◽  
Rapid Deceleration ◽  
Film Collapse ◽  
Theory And Experiment

This paper presents a theoretical model for the behavior of elastohydrodynamic films subjected to transient speed conditions, based on Grubin’s analytical solution for elastohydrodynamic lubrication. This model is applied to predict film thickness in high deceleration conditions. The model’s predictions are compared with the experimental results presented in an accompanying paper entitled “Elastohydrodynamic Film Collapse During Rapid Deceleration. Part I: Experimental Results.”

Theoretical and experimental studies of the oil film in lubricated point contact

1966 ◽  
Vol 291 (1427) ◽  
pp. 520-536 ◽  
Keyword(s):  
Surface Layer ◽  
Film Thickness ◽  
Strong Evidence ◽  
Experimental Studies ◽  
Point Contact ◽  
Elastohydrodynamic Lubrication ◽  
Experimental Results ◽  
Point Contacts ◽  
Previous Theory ◽  
Oil Film

A technique using Newton’s rings for mapping the oil film of lubricated point contacts is described. A theoretical value for the film thickness of such contacts in elastohydrodynamic lubrication is derived. The experimental results give the exit constriction predicted by previous theory but never shown in detail. The comparison of theoretical and experimental oil film thicknesses, which is satisfactorily accurate, gives strong evidence for a viscous surface layer some 1000Å thick. This film agrees with the known ‘lubricating power’ of the various oils tested.

Report Paper 3: Elastohydrodynamic Lubrication of ‘O’ Ring Seals

1969 ◽  
Vol 184 (12) ◽  
pp. 197-200
Author(s):  
I. A. Gibson ◽  
C. J. Hooke ◽  
J. P. O'Donoghue
Keyword(s):  
Theoretical Analysis ◽  
Film Thickness ◽  
Pressure Gradient ◽  
Contact Zone ◽  
Elastohydrodynamic Lubrication ◽  
Iterative Solution ◽  
Contact Conditions ◽  
Dry Contact

This report gives details of a theoretical analysis of the lubrication of ‘O’ ring seals. Under dry contact conditions the pressure gradient at inlet to the contact zone is infinite, and an iterative solution has been developed to determine the inlet sweep of pressure under conditions of elastohydrodynamic lubrication. The exit film thickness and pressures have also been determined for conditions of variable outlet viscosity and pressure gradient. Typical results for an ‘O’ ring are given for a standard seal section.

Computational analysis of the steady state performance of an adjustable/controllable multi-pad bearing profile under LBP orientations

2020 ◽  
pp. 095440622095770
Author(s):  
Girish Hariharan ◽  
Raghuvir Pai
Keyword(s):  
Steady State ◽  
Theoretical Model ◽  
Theoretical Analysis ◽  
Film Thickness ◽  
Computational Analysis ◽  
Fluid Film ◽  
Adjustable Mechanism ◽  
State Behaviour ◽  
Steady State Behaviour ◽  
Steady State Performance

A theoretical model of a four-pad bearing profile with unique adjustable or controllable features is simulated in the present study by considering load directed between the pads. Radial and tilt adjustable mechanism of the four bearing pads can effectively control and modify the rotor operating behaviour. Inward and outward motions of the bearing pads result in the generation of narrow and broader convergent regions, which directly influences the fluid film pressures. In the theoretical analysis, load-between-pad (LBP) orientations and pad adjustment configurations are taken account of by employing a modified film thickness equation. The effect of load position in influencing the steady state behaviour of the four-pad adjustable bearing under varied pad displaced conditions is analysed in this study. The outcome of the analysis highlighted the effectiveness of four-pad adjustable bearing in improving the steady state performance by operating under negative adjustment conditions and with load acting on the bearing pads.

Effect of Load Variation on Elastohydrodynamic Lubrication Film Collapse

2014 ◽  
Vol 592-594 ◽  
pp. 1366-1370
Author(s):  
Tapash Jyoti Kalita ◽  
Punit Kumar
Keyword(s):  
Film Thickness ◽  
Reynolds Equation ◽  
Elastohydrodynamic Lubrication ◽  
Transient Behavior ◽  
Computer Code ◽  
Practical Situation ◽  
Lubrication Film ◽  
Newton Raphson ◽  
Simulation Results ◽  
Film Collapse

Elastohydrodynamic line contact simulations have been carried out in the present study. A practical situation of transient EHL film collapse has been analyzed. The aim is to observe the effect of variation of maximum Hertzian pressure (PH) on transient behavior of EHL film thickness (H).The analysis is based upon classical Reynolds equation considering time variation. The simulation results pertaining to EHL film thickness calculated using linear pressure-viscosity relationship have been compared for different values of load. It has been observed that film thickness reduces with increase in load. Similar results are obtained using exponential pressure-viscosity relationship and compared with those for linear pressure-viscosity. The EHL equations are solved by discretizing Reynolds equation and load equilibrium equation along with other equations using Newton-Raphson technique with the help of a computer code.

Elastohydrodynamic Film Thickness in Concentrated Contacts: Part 2: Correlation of Experimental Results with Elastohydrodynamic Theory

1986 ◽  
Vol 200 (3) ◽  
pp. 219-226 ◽  
Author(s):  
R J Chittenden ◽  
D Dowson ◽  
C M Taylor
Keyword(s):  
Film Thickness ◽  
Experimental Studies ◽  
Elastohydrodynamic Lubrication ◽  
Operating Conditions ◽  
Experimental Results ◽  
Experimental Techniques ◽  
Dimensionless Parameters ◽  
Wide Range ◽  
Theoretical Predictions ◽  
Computational Procedures

The existence of a coherent film of lubricant between highly loaded machine elements has been recognized for many years. Over this period of time measurements of film thickness have gone hand in hand with theoretical analyses in the field now known as elastohydrodynamic lubrication. The experimental techniques of capacitance, electrical resistance and X-ray measurement have been supplemented by the use of optical interferometry while the analytical expressions obtained with the use of elegant simplifications have been superseded by those developed from extensive and comprehensive computational procedures. These developments in experimental techniques have yielded a substantial number of measurements of both minimum and central film thickness. Likewise, the advent of the digital computer has allowed the derivation of a large number of solutions to the problem of elastohydrodynamic lubrication of concentrated contacts. All these results, covering a wide range of geometrical conditions, are to be found in the literature, yet little attempt appears to have been made to assemble a representative set of experimental data to permit a detailed evaluation of the theoretical formulae for elliptical contacts. The second part of this paper therefore considers the correlation between a number of experimental studies covering a wide range of operating conditions and geometries, and the predictions of recent elastohydrodynamic theory. Some of the important aspects of each set of experimental results are then considered and examples are provided which illustrate the following points: 1. Good estimates of lubricant film thickness may be obtained from the theoretical expressions recently derived, even when the dimensionless parameters involved are outside the ranges considered in the derivation of the formulae. 2. The discrepancies which exist between theoretical predictions and some of the measured film thicknesses are nevertheless quite large, even when the dimensionless parameters are within their usual limits. On the whole there is good agreement between experiment and theory, while the general trend of the results indicates that theoretical predictions may underestimate the minimum film thickness by about 10 per cent and the central film thickness by about 25 per cent. This measure of agreement is quite remarkable when the extreme difficulty of interpreting the magnitudes of effective and very thin mean film thicknesses between machined components in various forms of experimental equipment is considered.

ASYMMETRIC CELLS AND ROTATING RINGS IN CELLULAR FLAMES

1996 ◽  
Vol 10 (28) ◽  
pp. 1379-1387 ◽  
Author(s):  
GEMUNU H. GUNARATNE ◽  
MOHAMED EL-HAMDI ◽  
MICHAEL GORMAN ◽  
KAY A. ROBBINS
Keyword(s):  
Theoretical Model ◽  
Normal Form ◽  
Theoretical Analysis ◽  
Circular Domain ◽  
Experimental Results ◽  
Premixed Flame ◽  
Polar Coordinates ◽  
Cellular Flames ◽  
Pattern Forming ◽  
Parity Breaking

Theoretical analysis and experimental results are presented to demonstrate the universal characteristics of parity-breaking bifurcations for pattern-forming systems in a circular domain. Ordered patterns of concentric rings of cells which form in a premixed flame on a circular burner at low pressure are used to demonstrate these ideas. Cells belonging to stationary rings are symmetric, while those of rotating rings are not. The important characteristics of the experimental results are reproduced in a theoretical model which can be numerically integrated in polar coordinates. Normal form equations for the Fourier–Bessel coefficients of this model lead to parity breaking.

scholarly journals Evaluation of the deformation shape of a balloon-type dielectric elastomer actuator prestretched with water pressure

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Natsumi Koike ◽  
Takeshi Hayakawa
Keyword(s):  
Theoretical Model ◽  
Theoretical Analysis ◽  
Good Accuracy ◽  
Water Pressure ◽  
Dielectric Elastomer ◽  
Experimental Results ◽  
Dielectric Elastomer Actuator ◽  
Elastomeric Material ◽  
Mechanical Models ◽  
Applicable Range

AbstractIn this study, we evaluated the deformation shape of a balloon-type dielectric elastomer actuator (DEA) that has been prestretched with water pressure. We fabricated the DEA with poly(dimethylsiloxane) (PDMS) as the elastomeric material and carbon grease as the electrode. We derived analytical solutions for the deformation of the DEA based on structural mechanical models. Additionally, we compared the deformation shapes obtained by theoretical analysis and experimental results. Our model can partially predict the deformation shape of the DEA with good accuracy. In addition, we discuss the applicable range of the theoretical model and error relative to the experimental results.

scholarly journals Возбуждение и регистрация нелинейного резонанса колебаний пружинного маятника с использованием электромагнитной индукции

2020 ◽  
Vol 90 (1) ◽  
pp. 5
Author(s):  
И.С. Зейликович ◽  
А.В. Никитин ◽  
А.Е. Василевич
Keyword(s):  
Numerical Simulation ◽  
Theoretical Model ◽  
Analytical Solution ◽  
Electromagnetic Induction ◽  
Nonlinear Oscillations ◽  
Nonlinear Effects ◽  
Oscillatory System ◽  
Experimental Results ◽  
Induction Method ◽  
Simulation Results

The nonlinear oscillations and resonances of the spring pendulum are experimentally and theoretically investigated. A unified by electromagnetic induction method of excitation, dissipation and registration of nonlinear oscillations is proposed. Experimental results demonstrate typical nonlinear effects, such as nonisochronism and bistability of vibrations. A theoretical model of the oscillatory system, leading to the Duffing equation, is proposed, an analytical solution and numerical simulation results are given, which agree well with the experiment.

scholarly journals Fractal Derivative Model for Air Permeability in Hierarchic Porous Media

2012 ◽  
Vol 2012 ◽  
pp. 1-7 ◽  
Author(s):  
Jie Fan ◽  
Jihuan He
Keyword(s):  
Porous Media ◽  
Theoretical Model ◽  
Theoretical Analysis ◽  
Air Permeability ◽  
Experimental Results ◽  
The Novel ◽  
Geometric Properties ◽  
Fractal Derivative ◽  
Derivative Method ◽  
First Time

Air permeability in hierarchic porous media does not obey Fick's equation or its modification because fractal objects have well-defined geometric properties, which are discrete and discontinuous. We propose a theoretical model dealing with, for the first time, a seemingly complex air permeability process using fractal derivative method. The fractal derivative model has been successfully applied to explain the novel air permeability phenomenon of cocoon. The theoretical analysis was in agreement with experimental results.

scholarly journals Experiment and Theoretical Analysis Study of ETFE Inflatable Tubes

2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
YanLi He ◽  
WuJun Chen
Keyword(s):  
Field Theory ◽  
Theoretical Analysis ◽  
Bifurcation Theory ◽  
Experimental Results ◽  
Load Bearing Capacity ◽  
Analysis Study ◽  
Bending Load ◽  
Wrinkling Analysis ◽  
Tension Field Theory ◽  
Theory And Experiment

The load bearing capacity of an ETFE (ethylene-tetra-fluoro-ethylene) inflatable tube is tested in this paper, and a comparative study of two wrinkling theories, the bifurcation theory and the tension field theory, is carried out for wrinkling analysis of the ETFE inflatable tube. Results obtained from the bifurcation theory and experiment reveal the limitations of tension field theory on the wrinkling analysis. The load-displacement curves of inflatable beams under bending load are obtained and compared with the experimental results; curves obtained using the bifurcation theory show coincidence with experimental curves, but the curves obtained using the tension field theory have noticeable deviations between calculated and experimental results.

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