Dynamic Characteristics of Gas-Lubricated Slider Bearings Under High Knudsen Number Conditions

1990 ◽  
Vol 112 (1) ◽  
pp. 111-118 ◽  
Author(s):  
T. Hayashi ◽  
S. Fukui ◽  
T. Ohkubo ◽  
R. Kaneko
Keyword(s):  
Boltzmann Equation ◽  
Knudsen Number ◽  
Dynamic Characteristics ◽  
Slip Flow ◽  
Magnetic Disk ◽  
Storage Devices ◽  
Disk Storage ◽  
Slider Bearings ◽  
Lubrication Equation ◽  
Flow Approximation

This paper presents numerical analyses of the dynamic characteristics of gas-lubricated slider bearings under high Knudsen number conditions using a generalized lubrication equation based on the the Boltzmann equation. These analyses are compared with those of the slip flow approximation equations and the differences are clarified. The present analysis is applied to the dynamic response of flying head sliders for magnetic disk storage devices. For a small slider with ultra-thin spacing, the deviations of the slip flow approximation equations are remarkable in regard to steady flying characteristics, but insignificant in regard to dynamic characteristics.

Experimental Investigation of Externally Pressurized Bearings Under High Knudsen Number Conditions

1988 ◽  
Vol 110 (1) ◽  
pp. 144-147 ◽  
Author(s):  
S. Fukui ◽  
R. Kaneko
Keyword(s):  
Experimental Investigation ◽  
Boltzmann Equation ◽  
Knudsen Number ◽  
Numerical Results ◽  
Experimental Results ◽  
Molecular Flow ◽  
Free Molecular Flow ◽  
Transition Flow ◽  
Lubrication Equation ◽  
Medium Vacuum

The characteristics of the externally pressurized bearings under high Knudsen number conditions were investigated experimentally by the use of surface restriction bearings in a medium vacuum on the order of 0.1 kPa (10−3 atm.). The experimental results agreed well with the numerical results calculated from a generalized lubrication equation based on the Boltzmann equation. Therefore, it would appear that this generalized lubrication equation is valid even when flows are categorized into transition flow or free molecular flow.

Thin Spacing Analysis for Head-Tape Interface

1996 ◽  
Vol 118 (4) ◽  
pp. 800-806 ◽  
Author(s):  
Kazuo Sakai ◽  
Yasumasa Nagawa ◽  
Koetsu Okuyama ◽  
Takao Terayama
Keyword(s):  
Surface Roughness ◽  
Boltzmann Equation ◽  
Flow Model ◽  
Slip Flow ◽  
First Order ◽  
Lubrication Equation ◽  
Linearized Boltzmann Equation ◽  
Deformation Equation ◽  
High Density Magnetic Recording ◽  
Average Flow Model

Very thin head-tape spacing, combining contact and floating conditions, is investigated for high density magnetic recording. A generalized lubrication equation, based on a linearized Boltzmann equation, is coupled with the tape deformation equation for analysis. Tape-surface roughness is also taken into account in the lubrication equation. The average flow model is adopted to analyzing tape-surface roughness. For very thin spacing conditions, it is found that the spacing based on the linearized Boltzmann equation is smaller than that based on first-order slip flow, and larger than that based on second-order slip flow. It is also found that considering tape-surface roughness reduces the calculated minimum spacing. Analytical results agreed with the experimental ones.

Effects of Moving Three-Dimensional Nano-Textured Disk Surfaces on Thin Film Gas Lubrication Characteristics for Flying Head Slider Bearings in Magnetic Disk Storage

2000 ◽  
Vol 123 (1) ◽  
pp. 151-158 ◽  
Author(s):  
Norio Tagawa ◽  
Takefumi Hayashi ◽  
Atsunobu Mori
Keyword(s):  
Thin Film ◽  
Three Dimensional ◽  
Flying Height ◽  
Magnetic Disk ◽  
Disk Storage ◽  
Head Slider ◽  
Slider Bearings ◽  
Linearized Boltzmann Equation ◽  
Gas Lubrication ◽  
Lubrication Characteristics

This paper describes the effects of moving three-dimensional nano-textured or patterned disk surfaces on thin film gas lubrication characteristics for flying head slider bearings in magnetic disk storage. In order to perform the most realistic simulation of slider flying characteristics over the textured disk surfaces, the direct numerical simulation method is used, instead of using various averaging techniques. Therefore, a deterministic description of the texture is adopted in this study. A dynamic analysis of the slider responses can be carried out, by solving the air bearing equation based on the linearized Boltzmann equation with the equations of motion of the slider under the excitation of the moving texture simultaneously. The slider’s dynamic responses to moving spaced bumps disk surfaces, including both the circumferentially and radially ridged disk surfaces, are computed systematically and basic slider dynamics over patterned disk surfaces is investigated. The effects of the texture area ratios (= texture width/texture pitch) in the circumferential and radial directions on the slider spacing dynamic modulations as well as the slider static flying characteristics are also studied. Furthermore, the effects of three kinds of texture patterns on the slider flying characteristics are investigated. Considering those simulation results, the design optimization for the texture pattern that minimizes not only the slider static flying height increase but also spacing dynamic modulations is discussed in order to achieve ultra-high density proximity magnetic recording.

Dynamics of Air-Lubricated Slider Bearings for Noncontact Magnetic Recording

1971 ◽  
Vol 93 (2) ◽  
pp. 272-278 ◽  
Author(s):  
T. Tang
Keyword(s):  
High Speed ◽  
Degrees Of Freedom ◽  
Reynolds Equation ◽  
Equations Of Motion ◽  
Two Dimensions ◽  
Direct Access ◽  
Slider Bearing ◽  
Storage Devices ◽  
Disk Storage ◽  
Slider Bearings

One of the key technologies which led to the success of modern magnetic disk storage devices is the development of self acting gas lubricated slider bearings for positioning a magnetic head precisely over a high speed rotating recording disk. This paper covers a dynamic simulation of such an air bearing system used in direct access disk storage devices. In the simulation model, the Reynolds equation, which describes the dynamics of the lubricating air film, is solved by finite difference techniques in two dimensions and time for compressible, isothermal flow. The equations of motion of the slider bearing are solved simultaneously with the Reynolds equation for three degrees of freedom. Applications of the simulation are demonstrated, and experimental measurements to verify the theory are presented and discussed.

A Database for Interpolation of Poiseuille Flow Rates for High Knudsen Number Lubrication Problems

1990 ◽  
Vol 112 (1) ◽  
pp. 78-83 ◽  
Author(s):  
S. Fukui ◽  
R. Kaneko
Keyword(s):  
Boltzmann Equation ◽  
Knudsen Number ◽  
Flow Rate ◽  
Poiseuille Flow ◽  
Interpolation Method ◽  
Numerical Calculations ◽  
Flow Rates ◽  
Lubrication Equation ◽  
Linearized Boltzmann Equation ◽  
Rapid Calculation

This paper proposes the use of a Poiseuille flow rate database for rapid calculation of a generalized lubrication equation for high Knudsen number gas films. The database is created by numerical calculations based on the linearized Boltzmann equation. The proposed interpolation method is verified to reduce calculation time to several tenths of that required to perform rigorous calculations with the same accuracy.

Sign in / Sign up

Export Citation Format

Share Document