Elastic Deformation of Surface Roughness in Thin Film Hydrodynamic Lubrication

2011 ◽  
Author(s):  
Kazuyuki Yagi ◽  
Joichi Sugimura
Keyword(s):  
Thin Film ◽  
Elastic Deformation ◽  
Small Amplitude ◽  
Reynolds Equation ◽  
Hydrodynamic Lubrication ◽  
Rigid Surface ◽  
Local Pressure ◽  
One Dimensional ◽  
Compliant Surface ◽  
The One

In the current study, the influence of elastic deformation in thin film hydrodynamic lubrication was numerically investigated. The one dimensional Reynolds equation was solved with considering the piezoviscosity effect of the lubricant and elastic deformation of the sliding surface in flat-flat contacts. The contact area comprised of a stationary rigid surface with sine waves with amplitude of several nano meters and a moving flat compliant surface. The obtained numerical results show that small amplitude of roughness compared with the averaged film thickness influences the pressure distribution of the hydrodynamic film. Reduction of the roughness and decay in wave of the roughness occurred because of the elastic deformation induced by local pressure generation.

First Paper: A General Approach to Hydraulic Lock

1967 ◽  
Vol 182 (1) ◽  
pp. 595-602 ◽  
Author(s):  
P. Dransfield ◽  
D. M. Bruce ◽  
M. Wadsworth
Keyword(s):  
Reynolds Equation ◽  
Lateral Force ◽  
Hydraulic Control ◽  
Dimensional Solution ◽  
One Dimensional ◽  
Particular Solutions ◽  
Piston Cylinder ◽  
The One ◽  
Hydraulic Control System ◽  
General Method

The present state of knowledge on the hydraulic lock phenomena of oil hydraulic control system components is reviewed briefly. A general one-dimensional solution of the Reynolds equation which governs hydraulic lock is presented. The solution embraces the particular solutions of past workers, and allows ready solution for piston-cylinder configurations for which a one-dimensional solution is adequate. A general method for making full solutions of the Reynolds equation is presented, requiring the use of a digital computer for particular solutions. Pressure distribution, the lateral force on the piston which produces hydraulic lock, and the location of the lateral force can be obtained. The commonly occurring case of a single-land piston lying tilted in its bore is examined in detail. The limit of accuracy of a one-dimensional solution is clearly shown by illustrating the discrepancies between the one-dimensional and two-dimensional solutions for several configurations.

A Simplified One-Dimensional Thermal Model for Journal Bearings

2007 ◽  
Vol 130 (1) ◽  
Author(s):  
Daquan Liu ◽  
Wen Zhang ◽  
Tiesheng Zheng
Keyword(s):  
Thermal Effects ◽  
Thermal Model ◽  
Reynolds Equation ◽  
Computing Time ◽  
One Dimensional ◽  
Lubricating Film ◽  
Direct Solution Method ◽  
The One ◽  
Generalized Reynolds Equation ◽  
Good Agreement

The variational approach, which is used to solve the Reynolds equation based on the assumption of constant temperature, is extended to the generalized Reynolds equation calculation. The direct solution method of the generalized Reynolds equation is presented, where the pressure of the nodal points and the cavitation zone boundary of the film can be determined without iterating. A simplified one-dimensional thermal model is built on the basis of the original two-dimensional thermal model. The model not only concerns the thermal effects of the lubricating film, but also offers a direct and rapid numerical algorithm for solving lubricating film temperature field. The numerical results of the temperature distributions for the one model are in good agreement with experiment, and less computing time is needed.

Effects of the Multilayer Structure on the Responsivity of Pyroelectric Thin Film Detectors

1994 ◽  
Vol 360 ◽  
Author(s):  
Zhu Jianguo ◽  
Xiao Dingquan ◽  
Qian Zhenghong ◽  
Zhang Wen ◽  
Du Siaosong
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Integrated Circuit ◽  
Multilayer Structure ◽  
Modulation Frequency ◽  
Flow Equation ◽  
One Dimensional ◽  
The One ◽  
Direct Incorporation ◽  
Room Temperature Operation

AbstractPyroelectric thin film detectors have advantages of wavelength independent sensitivity, room temperature operation and direct incorporation with integrated circuit amplifiers. Pyroelectric thin films with good quality have be prepared by many advanced thin film technologies [1-2]. The responsivity of pyroelectric thin film detectors is dependent on the thermal properties of the substrate, on which pyroelectric thin film detectors are prepared. The heat conduction in the detectors was investigated using the one-dimensional heat flow equation and the expressions describing the detectors performance were derived for pyroelectric thin films detectors with multilayer structure. The numerical simulation showed that the pyroelectric thin film detectors need effective heat isolation. If the air gap could be the heat isolation layer, which is between the bottom electrode and substrate, the iesponsivity of detectors would be higher than that of detectors which have no heat isolation in certain modulation frequency range.

Fluid Flow Through Microscale Fractal-Like Branching Channel Networks

2003 ◽  
Vol 125 (6) ◽  
pp. 1051-1057 ◽  
Author(s):  
Ali Y. Alharbi ◽  
Deborah V. Pence ◽  
Rebecca N. Cullion
Keyword(s):  
Boundary Layers ◽  
Three Dimensional ◽  
Heat Fluxes ◽  
Dimensional Model ◽  
Local Pressure ◽  
Flow Area ◽  
One Dimensional ◽  
Fluid Properties ◽  
Flow Through ◽  
The One

Flow through fractal-like branching networks is investigated using a three-dimensional computational fluid dynamics approach. Results are used to assess the validity of, and provide insight for improving, assumptions imposed in a previously developed one-dimensional model. Assumptions in the one-dimensional model include (1) reinitiating boundary layers following each bifurcation, (2) constant thermophysical fluid properties, and (3) negligible minor losses at the bifurcations. No changes to the redevelopment of hydrodynamic boundary layers following a bifurcation are recommended. It is concluded that temperature varying fluid properties should be incorporated in the one-dimensional model to improve its predictive capabilities, especially at higher imposed heat fluxes. Finally, a local pressure recovery at each bifurcation results from an increase in flow area. Ultimately, this results in a lower total pressure drop and should be incorporated in the one-dimensional model.

Induced One-Dimensional Waves in Elastic Nonconductors

1967 ◽  
Vol 34 (4) ◽  
pp. 937-941 ◽  
Author(s):  
E. K. Walsh
Keyword(s):  
Small Amplitude ◽  
Heat Supply ◽  
Body Force ◽  
The Body ◽  
One Dimensional ◽  
Material Parameters ◽  
Similar Relation ◽  
Acceleration Waves ◽  
The One ◽  
Explicit Relation

The influence of a propagating discontinuity in the extrinsic body force and heat supply on the amplitude of induced shock and acceleration waves is studied. These waves are considered in the sense of moving surfaces of discontinuity in certain field quantities associated with a motion of the body. In the case of acceleration waves, an explicit relation is derived for the amplitude of the wave in terms of the extrinsic forces and the material parameters. A similar relation is exhibited for shock waves of small amplitude. Only the one-dimensional case is considered here and the material is assumed to be a nonconductor of heat.

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