Asymptotic Methods for an Infinitely Long Step Slider Squeeze Bearing

1973 ◽  
Vol 95 (2) ◽  
pp. 208-215 ◽  
Author(s):  
R. C. DiPrima
Keyword(s):  
Steady State ◽  
Singular Perturbation ◽  
Film Thickness ◽  
Asymptotic Methods ◽  
Perturbation Techniques ◽  
Bearing Number

The step slider squeeze bearing is analyzed by a combination of singular perturbation techniques and numerical procedures. It is assumed that the bearing number associated with the trailing section is large and that the amplitude of the squeezing motion is small. There is no restriction on the film clearance or the jump in the film thickness at the step, so the bearing number associated with the leading section of the bearing need not be large. Results for the steady-state load are given for several geometries. Stability characteristics of different geometries are discussed.

Asymptotic Methods for a General Finite Width Gas Slider Bearing

1978 ◽  
Vol 100 (2) ◽  
pp. 254-260 ◽  
Author(s):  
J. A. Schmitt ◽  
R. C. DiPrima
Keyword(s):  
Film Thickness ◽  
Asymptotic Expression ◽  
Asymptotic Methods ◽  
Finite Width ◽  
Slider Bearing ◽  
Sliding Direction ◽  
Special Cases ◽  
Load Carrying ◽  
The Individual ◽  
Bearing Number

The method of matched asymptotic expansions is used to develop an asymptotic expression for the load-carrying capacity of a finite width gas slider bearing for large bearing numbers and for film thicknesses varying both in the sliding and transverse directions. The individual terms in the formula for the load are independent of the bearing number and are related to the interior portion, the side edge boundary layers, and the trailing edge boundary layer of the bearing. Only the terms associated with the side leakage phenomena must be computed numerically. Two special cases are discussed: (i) the film thickness varying only in the sliding direction, and (ii) the film thickness having linear or parabolic variation in the sliding direction and parabolic variation in the transverse direction.

Effect of Rolling Velocity and Maximum Hertzian Pressure on Fluid Film in Steady State EHL Line Contact with Rough Surface and Linear Piezoviscosity

2014 ◽  
Vol 592-594 ◽  
pp. 1371-1375
Author(s):  
Nitesh Talekar ◽  
Punit Kumar
Keyword(s):  
Surface Roughness ◽  
Steady State ◽  
Film Thickness ◽  
Rough Surface ◽  
Computer Code ◽  
Fluid Film ◽  
Line Contact ◽  
Rolling Velocity ◽  
Load Carrying ◽  
Lubricated Contact

Consideration of surface roughness in steady state EHL line contact is the first step towards understanding the lubrication of rough surface problem. Current paper investigates the use of sinusoidal waviness in the contact; more precisely it gives performance of real fluid in EHL line contact. The effect of various parameters like rolling velocity (U) and maximum Hertzian pressure (ph) on surface roughness by using properties of linear and exponential piezo-viscosity is taken into consideration to evaluate behavior of pressure distribution of load carrying fluid film and film thickness. Full isothermal, Newtonian simulation of EHL problem gives described effects. Spiking or fluctuation of pressure and film thickness curves is expected to show presence of irregularities on the surface chosen and amount of fluctuation depends on certain parameters and intensity of irregularities present. Rolling side domain of-4.5 ≤ X ≤ 1.5 with grid size ∆X=0.01375 is selected. A computer code is developed to solve Reynolds equation, which governs the generation of pressure in the lubricated contact zone is discritized and solved along with load balance equation using Newton-Raphson technique.

Asymptotic Methods for an Infinite Slider Bearing With a Discontinuity in Film Slope

1976 ◽  
Vol 98 (3) ◽  
pp. 446-452 ◽  
Author(s):  
J. A. Schmitt ◽  
R. C. DiPrima
Keyword(s):  
Boundary Layer ◽  
Film Thickness ◽  
Asymptotic Expansions ◽  
Asymptotic Expression ◽  
Asymptotic Methods ◽  
Matched Asymptotic Expansions ◽  
Slider Bearing ◽  
Trailing Edge ◽  
Slider Bearings ◽  
Special Cases

The method of matched asymptotic expansions is used to develop an asymptotic expression for the pressure for large bearing numbers for the case of an infinite slider bearing with a general film thickness that has a discontinuous slope at a point. It is shown that, in addition to the boundary layer of the pressure at the trailing edge, there is also a boundary layer in the derivative of the pressure at the point of discontinuity. The corresponding load formula is also derived. The special cases of the taper-flat and taper-taper slider bearings are discussed.

Numerical Solution of the Planar Hydrostatic Foil Bearing

1979 ◽  
Vol 101 (1) ◽  
pp. 86-91 ◽  
Author(s):  
A. Eshel
Keyword(s):  
Steady State ◽  
Film Thickness ◽  
Computer Program ◽  
Numerical Solution ◽  
Asymptotic Approach ◽  
State Problem ◽  
Shooting Technique ◽  
Foil Bearing ◽  
Approach To Steady State ◽  
Steady State Problem

The steady state problem of the planar hydrostatic foil bearing is analyzed and solved numerically. Two techniques of solution are used. One method is simulation in time with asymptotic approach to steady state. This is achieved by a preprocessor which automatically sets up the numerical computer program. The second method is an iterative shooting technique. The results agree well with one another. Curves of pressure and typical film thickness versus flow are presented.

EHD Film Thickness in Non-Steady State Contacts

1998 ◽  
Vol 120 (3) ◽  
pp. 442-452 ◽  
Author(s):  
J. Sugimura ◽  
W. R. Jones ◽  
H. A. Spikes
Keyword(s):  
Steady State ◽  
Film Thickness ◽  
Ultrathin Film ◽  
Contact Conditions ◽  
Steady State Motion ◽  
Base Oils ◽  
Different Types ◽  
Mineral Base

This paper describes a study of EHD film thickness in non-steady state contact conditions. A modification of ultrathin film interferometry is employed which is able to measure both central film thickness and film thickness profiles 50 times a second. Film thickness with two perfluoropolyethers and two mineral base oils are investigated in a number of different types of non-steady state motion, including acceleration/deceleration, stop/start and reciprocation. The results demonstrate a range of transient behaviors of EHD film whose thicknesses deviate from those in steady state conditions.

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