Loading Velocity Effect in the Load/Unload Systems With Multiple Flying Height States

2008 ◽  
Vol 131 (1) ◽  
Author(s):  
Polina V. Khan ◽  
Pyung Hwang
Keyword(s):  
Dynamic Loading ◽  
Continuation Method ◽  
Leading Edge ◽  
Disk Drive ◽  
Numerical Continuation ◽  
Flying Height ◽  
Disk Contact ◽  
Air Lubrication ◽  
Velocity Effect ◽  
In The Beginning

The effect of the loading velocity on the loading process in the computer hard disk drive air slider system with multiple flying height states was studied numerically. The results of the static analysis were compared with the dynamic loading trajectories. The air lubrication problem was solved using the finite-element method. The static flying height states for variable suspension forces were considered as solution branches and were found by using a numerical continuation method. The dynamic loading trajectory was obtained iteratively by applying the Newmark method for the slider position and an implicit scheme for the air film pressure. Close agreement was found between the solution branches and the trajectories of dynamic loading with a velocity of 5 mm/s. At the higher velocities, the unstable negative pitching motion and the slider-disk contact at the slider’s leading edge were detected. Increasing the x-offset of the suspension point made it possible to complete loading with 10 mm/s. At the same time, increasing the x-offset led to the slider-disk contact at the slider’s trailing edge in the beginning of loading with a velocity exceeding 25 mm/s.

Bifurcation Approach to the Analysis of Multiple Flying Height States in Load/Unload Hard Disk Drive Systems

2005 ◽  
Author(s):  
Pyung Hwang ◽  
Polina V. Khan
Keyword(s):  
Hard Disk Drive ◽  
Hard Disk ◽  
Disk Drive ◽  
Numerical Continuation ◽  
Continuation Methods ◽  
Multiple Equilibrium ◽  
Flying Height ◽  
Drive Systems ◽  
The Relationship ◽  
Force Equilibrium

The application of numerical continuation methods to calculate suspension force-equilibrium position curve for hard disk drive sliders is proposed. The method efficiently detects multiple equilibrium positions. The relationship between suspension force offset and critical preload is found for the femto slider.

Numerical Simulations of Slider Interaction With Multiple Asperity Using Hertzian Contact Model

1995 ◽  
Vol 117 (4) ◽  
pp. 575-579 ◽  
Author(s):  
Ellis Cha ◽  
D. B. Bogy
Keyword(s):  
Disk Drive ◽  
Contact Model ◽  
Hertzian Contact ◽  
Flying Height ◽  
Radius Of Curvature ◽  
Asperity Contact ◽  
Disk Contact ◽  
Suspension Dynamics ◽  
Magnetic Hard Disk ◽  
Hertzian Contact Model

A numerical simulation of slider-disk contact in a magnetic hard disk drive is studied using the Hertzian contact model. The slider-disk contact is caused by flying height fluctuation due to disk runout for very low flying sliders. The rough disk topography is generated numerically by combining a sinusoidal waviness and a Gaussian roughness. For each asperity contact, the radius of curvature is calculated from the disk topography, and the radius is used to calculate the contact force using the Hertzian contact model. The slider’s response to a single asperity calculated using the Hertzian contact model agrees well with the result obtained using the impulse-momentum based contact model. The simulation results of slider-disk contact including suspension dynamics are calculated with and without friction for a “nano-slider.”

Bifurcation Analysis of the Load/Unload Systems With Multiple Flying Height States

2006 ◽  
Vol 128 (3) ◽  
pp. 665-669 ◽  
Author(s):  
Pyung Hwang ◽  
Polina V. Khan
Keyword(s):  
Disk Drive ◽  
Stability Diagram ◽  
Numerical Continuation ◽  
Continuation Methods ◽  
Flying Height ◽  
Air Bearing ◽  
Bearing Force ◽  
Characteristic Values ◽  
The Stability ◽  
The Relationship

The load/unload behavior of the hard disk drive slider is studied in terms of the air bearing static characteristics. The application of numerical continuation methods to calculate spacing diagrams is proposed. The algorithm that detects multiple flying height states and fold points is developed. The relationship between suspension force x-offset and critical preload is found for femto size sliders. The second fold corresponding to the critical preload for unloading is found in the negative air bearing force area. The range of x-offsets and preloads where bi-stable phenomenon exists is depicted on the stability diagram. The perturbation method is used to check the dynamic system characteristic values near the fold points and to determine the stability of the solution branches. The present procedure can be employed to study the multiple flying height states in the terms of any other pair of parameters besides the preload and x-offset.

The Influence of Temperature and Humidity on the ABS Contaminations

2014 ◽  
Author(s):  
Fuhao Cui ◽  
Jinhong Hu ◽  
Yue Peng ◽  
Hui Li ◽  
Shengnan Shen ◽  
...  
Keyword(s):  
Shear Stress ◽  
Flow Pattern ◽  
Air Flow ◽  
Disk Drive ◽  
Flying Height ◽  
Flow Shear ◽  
Slip Boundary ◽  
Temperature And Humidity ◽  
Flow Shear Stress ◽  
The Impact

In order to increase the areal recording density of hard disk drive beyond 1 Tb/in2, the flying height has to be reduced to several nanometers. At such a low flying height, particles and lube contaminations, which could lead to a transient vibration and flying height modulation in a hard disk drive, are becoming more and more serious. In this work, it studies the influence of temperature and humidity on the air flow pattern, velocity and shear stress distribution on the air bearing surface (ABS) of slider using a self-developed simulator. It first solves the generalized steady state Reynolds equation with slip boundary conditions. Then it solves the reduced Navier-Stokes (N-S) equation with slip boundary conditions to get the air velocity distribution, i.e., identify the air flow pattern on the ABS. The stagnation lines and areas of air flow are calculated to judge the contamination area. On the other hand, it calculates the air shear stress distribution on the ABS since the air shear stress is the main driving force for the lubricant and particles migration and contaminations. After that, the impact of the temperature and humidity on the air flow pattern is analyzed by applying the Sutherland equation and mixed gas viscosity calculation equation. The simulation results indicate that the impact of temperature and humidity on the air flow pattern is un-conspicuous. However, the peak velocity of the air flow, which contains no vapor, reduces almost 10%, and the peak air flow shear stress increases less than 1.5%, with the increase of operational temperature from 298.15 K to 343.15 K. In addition, the peak velocity of the air flow increasing almost 4%, and the peak air flow shear stress keeps almost same, with the increase of the operational mole fraction of vapor from 5% to 15%.

Numerical Solutions of Polynomial Equations for the Eight-Position Synthesis of the Cylindrical-Spherical Dyad

2012 ◽  
Author(s):  
Chintien Huang ◽  
Chenning Hung ◽  
Kuenming Tien
Keyword(s):  
Rigid Body ◽  
Numerical Solutions ◽  
Continuation Method ◽  
Quadratic Equation ◽  
Geometric Constraints ◽  
Numerical Continuation ◽  
Polynomial Equations ◽  
Quartic Polynomial ◽  
Solutions Of Equations ◽  
Position Synthesis

This paper investigates the numerical solutions of equations for the eight-position rigid-body guidance of the cylindrical-spherical (C-S) dyad. We seek to determine the number of finite solutions by using the numerical continuation method. We derive the design equations using the geometric constraints of the C-S dyad and obtain seven quartic polynomial equations and one quadratic equation. We then solve the system of equations by using the software package Bertini. After examining various specifications, including those with random complex numbers, we conclude that there are 804 finite solutions of the C-S dyad for guiding a body through eight prescribed positions. When designing spatial dyads for rigid-body guidance, the C-S dyad is one of the four dyads that result in systems of equal numbers of equations and unknowns if the maximum number of allowable positions is specified. The numbers of finite solutions in the syntheses of the other three dyads have been obtained previously, and this paper provides the computational kinematic result of the last unsolved problem, the eight-position synthesis of the C-S dyad.

Air Entrapment in Nanometer-Thick Lubricant Films and its Effect on Slider Flying Height in a Hard Disk Drive

2012 ◽  
Vol 47 (3) ◽  
pp. 349-355 ◽  
Author(s):  
B. Marchon ◽  
X. C. Guo ◽  
S. Canchi ◽  
R. H. Wang ◽  
N. Supper ◽  
...  
Keyword(s):  
Hard Disk Drive ◽  
Hard Disk ◽  
Disk Drive ◽  
Flying Height ◽  
Air Entrapment ◽  
Lubricant Films
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