Numerical Analysis of Microwaviness-Excited Vibrations of a Flying Head Slider in Proximity and Asperity Contact Regimes

2017 ◽  
Vol 2017 (0) ◽  
pp. A-02
Author(s):  
Kyosuke Ono
Keyword(s):  
Numerical Analysis ◽  
Asperity Contact ◽  
Head Slider

Elastic Contact and Friction Between Sliders and Circumferentially Textured Disks—Part I: Analytical Model

1998 ◽  
Vol 120 (1) ◽  
pp. 28-34 ◽  
Author(s):  
K. Tanaka ◽  
T. Kusumi
Keyword(s):  
Thin Film ◽  
Contact Angle ◽  
Numerical Analysis ◽  
Frictional Coefficient ◽  
Elastic Contact ◽  
Height Distribution ◽  
Head Slider ◽  
Real Contact ◽  
Dry Conditions ◽  
Weakly Dependent

This series of three papers presents an experimental and numerical analysis of the friction between a head slider and a thin-film rigid disk with circumferential surface texture, under various humidities. In Part I, we develop a model of a cylindrical contact of a slider rail with strong anisotropic asperities under dry conditions. This model predicts that the real contact pressure is primarily determined by the height distribution and geometry of asperities on the disk, whereas it is very weakly dependent on the surface curvature of the rail. The result of the latter calculation suggests that the frictional coefficient is insensitive to variation in the head contact angle due to head pitching motion.

Improved Analysis of Unstable Bouncing Vibration and Stabilizing Design of Flying Head Slider in Near-Contact Region

2006 ◽  
Vol 129 (1) ◽  
pp. 65-74 ◽  
Author(s):  
Kyosuke Ono ◽  
Masami Yamane
Keyword(s):  
Parametric Study ◽  
Contact Region ◽  
Disk Surface ◽  
Design Guidelines ◽  
Flying Height ◽  
Asperity Contact ◽  
Adhesion Forces ◽  
Characteristic Model ◽  
Head Slider ◽  
Contact Characteristic

This paper describes an improved analytical study of the bouncing vibration of a flying head slider in the near-contact region and gives quantitative designs guideline for realizing a stable flying head slider, based on the results of a parametric study. First, we numerically calculated the general characteristics of the contact and adhesion forces between a smooth contact pad and disk surface by considering asperity contact, the lubricant meniscus, and elastic bulk deformation. As a result, it was shown that the contact characteristics can be represented by a simple model with five independent parameters when the asperity density is large and the asperity height is small as in cases of current slider and disk surfaces. Then, we numerically computed the slider dynamics in a two degree of freedom slider model with nonlinear air-bearing springs by using the simplified contact characteristic model. As a result, we have obtained a self-excited bouncing vibration whose frequency, amplitude and touchdown/takeoff hysteresis characteristics agree much better with the experimental results compared with our previous analysis. From a parametric study for takeoff height, we could obtain design guidelines for realizing a stable head slider in a low flying height of 5nm or less.

Analysis of Microwaviness-Excited Vibrations of a Flying Head Slider in Asperity Contact Regime

2016 ◽  
Author(s):  
Kyosuke Ono
Keyword(s):  
Hard Disk Drives ◽  
Adhesive Contact ◽  
Flying Height ◽  
Design Parameters ◽  
Lubricant Layer ◽  
Asperity Contact ◽  
Head Slider ◽  
Spacing Variation ◽  
Parameter Values ◽  
Fly Height

The flying height of a head slider in hard disk drives has been decreased close to 1 nm but still must be reduced to ∼0.5 nm in order to increase recording density. At such a narrow spacing, variation in head/disk spacing caused by microwaviness (MW) becomes a significant concern [1]. Some comprehensive numerical simulations of slider dynamics in the near-contact and contact regimes have been conducted [2–5]. However, the real physics behind slider dynamics does not seem to be fully elucidated because the head-disk interfacial force changes with differences in interfacial design conditions such as the air-bearing surface, surface roughness, and lubricant layer. In this study, we evaluated head-disk interfacial forces by asperity adhesive contact theories with measured asperity parameter values. The MW-excited vibrations of a thermal fly-height control (TFC) slider in proximity and asperity contact regimes were simulated by changing the design parameters. It was found that the simulated results allow us to understand typical experimental results reported in previous literature.

Numerical Analysis Method of Contact Mechanics Between a Sphere and a Flat Considering Lennard-Jones Surface Forces of Contacting Asperities and All Rough Height Surfaces

2011 ◽  
Author(s):  
Kyosuke Ono
Keyword(s):  
Numerical Analysis ◽  
Contact Mechanics ◽  
Present Theory ◽  
Adhesive Contact ◽  
Surface Forces ◽  
Asperity Contact ◽  
Analysis Method ◽  
Surface Theory ◽  
Numerical Analysis Method ◽  
Lennard Jones

A new numerical analysis method for elastic adhesive contact mechanics between a sphere and a flat with a sub-nanometer roughness is presented. In contrast to conventional theories, the elastic deformations of both contacting asperities and mean height surface and Lennard-Jones (LJ) surface forces of both contacting asperities and all rough surfaces including valley areas are taken into account New adhesive force of contacting asperity is used from asperity contact analysis. Calculated results for head-disk asperity contact with current low roughness are shown in comparison with conventional theories. The relationship among present theory, mean height surface theory and perfectly smooth surface theory is discussed.

Numerical analysis of the effects of compression ring wear and cylinder liner deformation on the thermal mixed lubrication performance of ring-liner system

2018 ◽  
Vol 19 (2) ◽  
pp. 203 ◽  
Author(s):  
Cheng Liu ◽  
Yanjun Lu ◽  
Peng Wang ◽  
Yongfang Zhang ◽  
Yonggui Zhang ◽  
...  
Keyword(s):  
Numerical Analysis ◽  
Thermal Effect ◽  
Cylinder Liner ◽  
Mass Conservation ◽  
Asperity Contact ◽  
Friction Forces ◽  
Oil Film ◽  
Compression Ring ◽  
Lubrication Performance ◽  
Liner System

The lubrication performance of roughness compression ring-cylinder liner system (CRCL) with axial-asymmetric new/worn compression ring and out-of-round cylinder liner is studied in this paper. By considering the oil film thermal effect, cavitation phenomenon, and surface roughness, the energy equations, mass conservation Jacoboson-Floberg-Olsson (JFO) cavitation algorithm, generalized average Reynolds equation, and Greenwood-Tripp asperity contact model are employed to investigate the frictional behaviors of CRCL. The oil film thickness, friction forces, wear, and power loss of CRCL are investigated at various wear stages of compression ring. The effects of the magnitude of cylinder liner deformation on the frictional characteristics of CRCL are also analyzed with consideration of compression ring conformability. Numerical results show that the deformation of cylinder liner and the wear of compression ring have a significant influence on the lubrication performance. It also suggests that the oil film thermal effect should be considered in the numerical analysis to provide an accurate prediction on the frictional behaviors of CRCL.

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