scholarly journals An Alternative Simulation Method for Calculation of Microgas Flows under Flying Head Sliders

2009 ◽  
Vol 2009 ◽  
pp. 1-10 ◽  
Author(s):  
Ching Shen
Keyword(s):  
Reynolds Equation ◽  
Simulation Method ◽  
Air Bearing ◽  
Bearing Surface ◽  
Rotating Disc ◽  
Information Preservation ◽  
Precise Knowledge ◽  
Micrometer Size ◽  
Methods Of Calculations ◽  
Generalized Reynolds Equation

The precise knowledge of the force and moment generated by the air squeezed under the read-write slider by the rotating disc is an engineering necessity in designing the air bearing surface slider. This paper reviews methods addressing the thin gas film bearings problem. It firstly reviews briefly the relatively well-known two methods of calculations of the microgas flows under flying head sliders, the generalized Reynolds equation, having given a number of useful results of slider design, and the DSMC method, which is precise and appropriate for the flow of complex configurations but is restricted to miniature (~micrometer) size sliders. The main purpose of the paper is to introduce to the reader an alternative method, the information preservation (IP) method, for use in simulation of the flows under air bearing surfaces. Some recent results of IP simulation of slider flows published on conference proceedings are introduced here.

Design and Analysis of a Novel Micro Flying Head in Mass Storage System

2014 ◽  
Vol 599-601 ◽  
pp. 248-253
Author(s):  
Yu He Li ◽  
Kai Sen Guan ◽  
Da Peng Zhao ◽  
Yong Rong Qiu ◽  
Qing Xiang Li
Keyword(s):  
Structural Design ◽  
Reynolds Equation ◽  
Storage System ◽  
Air Bearing ◽  
Mass Storage ◽  
Bearing Surface ◽  
Mass Storage System ◽  
Fluid Theory ◽  
Volume Method ◽  
Generalized Reynolds Equation

In order to meet the mass storage system’s need for higher density and integration, a novel structural design for micro flying head is conceived and an air bearing surface is designed based on micro fluid theory of hydrodynamics. Both positive and negative pressures can be generated by the air bearing surface, with the stiffness and motion stability enhanced by negative pressure. A lubrication model has been investigated with 1.5 order slip model of the generalized Reynolds equation, and the finite volume method is used for the simulation of the flying characteristics. The theoretical analysis and experimental results show that the proposed micro flying head exhibits satisfying flying stability, with head-disk spacing less than 75nm, and carrying capacity exceeding 93mN.

Performance of Sliders Flying Over Discrete-Track Media

2007 ◽  
Vol 129 (4) ◽  
pp. 712-719 ◽  
Author(s):  
Jianhua Li ◽  
Junguo Xu ◽  
Yuki Shimizu
Keyword(s):  
Estimation Method ◽  
Simulation Method ◽  
Measured Data ◽  
Flying Height ◽  
Height Loss ◽  
Air Bearing ◽  
Slider Air Bearing ◽  
Discrete Track ◽  
Flying Attitude ◽  
Manufacturing Variation

A simulation method in which grooves are virtually distributed on the slider air bearing instead of on the grooved medium surface has been developed and used to investigate the performance of sliders flying over the surface of a discrete-track medium. The simulated flying height loss due to a discrete-track medium coincides well with the measured data, whereas the average-estimation method overestimates flying height loss. Among the characteristics of a slider flying over the surface of a discrete-track medium that were studied are the flying attitude, the effect of groove parameters on flying profile, and the flying height losses due to manufacturing variation and altitude. The results indicate that when a slider is flying over the surface of a discrete-track medium, it will have a higher 3σ of flying height, be more sensitive to altitude, and will have a greater flying height loss.

scholarly journals An Assessment of Quantitative Predictions of Deterministic Mixed Lubrication Solvers

2020 ◽  
Vol 143 (1) ◽  
Author(s):  
Yuechang Wang ◽  
Abdel Dorgham ◽  
Ying Liu ◽  
Chun Wang ◽  
Mark C. T. Wilson ◽  
...  
Keyword(s):  
Reynolds Equation ◽  
Thickness Distribution ◽  
Computation Time ◽  
Simulation Method ◽  
Coefficient Matrix ◽  
Mixed Lubrication ◽  
Contact Ratio ◽  
Lubricated Contacts ◽  
Discretization Schemes ◽  
Parametric Studies

Abstract The ability to simulate mixed lubrication problems has greatly improved, especially in concentrated lubricated contacts. A mixed lubrication simulation method was developed by utilizing the semi-system approach which has been proven to be highly useful for improving stability and robustness of mixed lubrication simulations. Then different variants of the model were developed by varying the discretization schemes used to treat the Couette flow terms in the Reynolds equation, varying the evaluation of density derivatives and varying the contribution of terms in the coefficient matrix. The resulting pressure distribution, film thickness distribution, lambda ratio, contact ratio, and the computation time were compared and found to be strongly influenced by the choice of solution scheme. This indicates that the output from mixed lubrication solvers can be readily used for qualitative and parametric studies, but care should be taken when making quantitative predictions.

Topological design sensitivity on the air bearing surface of head slider

2002 ◽  
Vol 16 (8) ◽  
pp. 1102-1108 ◽  
Author(s):  
Sang-Joon Yoon ◽  
Min-Soo Kim ◽  
Dong-Hoon Choi
Keyword(s):  
Design Sensitivity ◽  
Air Bearing ◽  
Bearing Surface ◽  
Head Slider ◽  
Topological Design

An Air Layer Modeling Approach for Air and Air/Vacuum Bearings

1997 ◽  
Vol 119 (3) ◽  
pp. 388-392
Author(s):  
J. M. Pitarresi ◽  
K. A. Haller
Keyword(s):  
Load Capacity ◽  
Load Resistance ◽  
High Load ◽  
Air Bearing ◽  
Air Bearings ◽  
Bearing Surface ◽  
Know How ◽  
Modeling Approach ◽  
Vibrational Characteristics ◽  
High Load Capacity

Air layer supported bearing pads, or “air bearings” as they are commonly called, are popular because of their high load capacity and low in-plane coefficient of friction, making them well suited for supporting moving, high accuracy manufacturing stages. Air/vacuum bearings enhance these capabilities by giving the bearing pad load resistance capacity in both the upward and downward directions. Consequently, it is desirable to know how to model the air layer between the bearing pad and the bearing surface. In this paper, a simple finite element modeling approach is presented for investigating the vibrational characteristics of an air layer supported bearing. It was found that by modeling the air layer as a bed of uniform springs who’s stiffness is determined by load-displacement tests of the bearing, a reasonable representation of the response can be obtained. For a bearing supported by air without vacuum, the dynamic response was very similar to that of a freely supported bearing. The addition of vacuum to an air bearing was found to significantly lower its fundamental frequency which could lead to unwanted resonance problems.

Geometry and Speed Effects on the Performance of the Herringbone Grooved Gas Lubricated Journal Bearing

2005 ◽  
Author(s):  
D. J. Foster
Keyword(s):  
Reynolds Equation ◽  
Journal Bearing ◽  
Groove Depth ◽  
Bearing Surface ◽  
Static Stiffness ◽  
Groove Pattern ◽  
Land Width

The plain gas lubricated journal bearing is dynamically unstable. The addition of grooving on the bearing surface has been found to overcome this instability. In particular, the herringbone groove pattern has been found to provide damping with increase of static stiffness. The effect of the available geometry characteristics on performance is computed from solution of the compressible Reynolds equation. The geometry features examined are groove angle, and the ratios:- groove depth to clearance, groove-to-land width, axial groove length to bearing length and bearing eccentricity. The performance is determined over a range of compressibility numbers.

Probabilistic Designs of Air-Bearing Surface on Manufacturing Tolerances

2004 ◽  
Author(s):  
Sang-Joon Yoon ◽  
Dong-Hoon Choi
Keyword(s):  
Design Optimization ◽  
Reliability Analysis ◽  
Computation Time ◽  
Probabilistic Constraints ◽  
Air Bearing ◽  
Probabilistic Design ◽  
Bearing Surface ◽  
Deterministic Optimization ◽  
Design Variables ◽  
Conventional Optimization

The focus in this paper is to automatically design the air-bearing surface (ABS) considering the randomness of its geometry as an uncertainty of design variables. Designs determined by the conventional optimization could only provide a low level of confidence in practical products due to the existence of uncertainties in either engineering simulations or manufacturing processes. This calls for a reliability-based approach to the design optimization, which increases product or process quality by addressing randomness or stochastic properties of design problems. In this study, a probabilistic design problem is formulated considering the reliability analysis which is employed to estimate how the fabrication tolerances of individual slider parameters affect the final flying attitude tolerances. The proposed approach first solves the deterministic optimization problem. Beginning with this solution, the reliability-based design optimization (RBDO) is continued with the probabilistic constraints affected by the random variables. Probabilistic constraints overriding the constraints of the deterministic optimization attempt to drive the design to a reliability solution with minimum increase in the objective. The simulation results of the probabilistic design are directly compared with the values of the initial design and the results of the deterministic optimum design, respectively. In order to show the effectiveness of the proposed approach, the reliability analyses by the Monte Carlo simulation are carried out. And the results demonstrate how efficient the proposed approach is, considering the enormous computation time of the reliability analysis.

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