Theoretical Prediction of Ramp Loading/Unloading Process in Hard Disk Drives

1999 ◽  
Vol 121 (3) ◽  
pp. 568-574 ◽  
Author(s):  
J. P. Peng
Keyword(s):  
Reynolds Equation ◽  
Dynamic Performance ◽  
Hard Disk Drives ◽  
Air Bearing ◽  
Disk Drives ◽  
Suction Force ◽  
Coupled Equations ◽  
Loading And Unloading ◽  
Volume Method ◽  
Unloading Time

Air bearing slider dynamic performance during the ramp loading and unloading processes was investigated theoretically in this paper. The air bearing was modeled by the modifiedcompressible Reynolds equation, and it was solved by the finite volume method. Slider dynamic equations were derived in this paper to include the ramp loading/unloading mechanism. These two sets of coupled equations were solved iteratively. Both Tripad and negative pressure air bearing (NPAB) were included in the analysis. Effects of loading/unloading velocity, disk rotational speed, as well as suspension flexure stiffness, were investigated. Slider-disk impact will occur during the Tripad loading process, especially at high loading velocity. On the other hand, this impact can be avoided for an NPAB at loading velocity up to 200 mm/s. However, an NPAB requires a longer unloading time due to its suction force. This unloading process is further delayed if a soft flexure is combined with an NPAB.

Local Adaptive Multi-Grid Control Volume Method for the Air Bearing Problem in Hard Disk Drives

2012 ◽  
Author(s):  
Liping Li ◽  
David B. Bogy
Keyword(s):  
Control Volume ◽  
Hard Disk Drives ◽  
Hard Disk ◽  
Adaptive Grid ◽  
Air Bearing ◽  
Disk Drives ◽  
Control Volume Method ◽  
Generating Method ◽  
The Stability ◽  
Volume Method

A new local adaptive grid-generating algorithm is developed and integrated with the multi-grid control volume method to simulate the steady state flying condition of air bearing sliders in HDDs (Hard Disk Drives) accurately and efficiently. Two sliders are used to demonstrate the applicability of this method. The results show that this new local adaptive grid-generating method improves substantially the stability and efficiency of the simulation scheme.

A Local Adaptive Multigrid Control Volume Method for the Air Bearing Problem in Hard Disk Drives

2013 ◽  
Vol 135 (3) ◽  
Author(s):  
Liping Li ◽  
David B. Bogy
Keyword(s):  
Control Volume ◽  
Hard Disk Drives ◽  
Hard Disk ◽  
Adaptive Grid ◽  
Uniform Mesh ◽  
Air Bearing ◽  
Disk Drives ◽  
Control Volume Method ◽  
Generating Method ◽  
Volume Method

A new, local-adaptive, grid-generating algorithm is developed and integrated with the multigrid control volume method to simulate the steady flying state of the air bearing sliders in hard disk drives (HDDs) accurately and efficiently. Local finer meshes (mesh dimension decreases to half) are created on the nodes of the current finest grids that have pressure gradients or geometry gradients larger than a predefined tolerance after the pressure distribution has been obtained on the initial uniform mesh. In this way, the pressure- or geometry-sensitive regions have higher resolution, leading to more accurate results without inefficiently larger meshes. Two sliders are used to demonstrate the applicability of this method. It is found that this new, local-adaptive, grid-generating method improves the stability and efficiency of the simulation scheme.

Effect of Intermolecular Forces on the Static and Dynamic Performance of Air Bearing Sliders: Part II—Dependence of the Stability on Hamaker Constant, Suspension Preload and Pitch Angle

2005 ◽  
Vol 128 (1) ◽  
pp. 203-208 ◽  
Author(s):  
Vineet Gupta ◽  
David B. Bogy
Keyword(s):  
Pitch Angle ◽  
Dynamic Performance ◽  
Hard Disk Drives ◽  
Intermolecular Forces ◽  
Flying Height ◽  
Total Force ◽  
Air Bearing ◽  
Force Increase ◽  
The Stability ◽  
Fly Height

Intermolecular and surface forces contribute significantly to the total forces acting on air bearing sliders for flying heights below 5 nm. Their contributions to the total force increase sharply with the reduction in flying height, and hence their existence can no longer be ignored in air bearing simulation for hard disk drives. Various experimentally observed dynamic instabilities can be explained by the inclusion of these forces in the model for low flying sliders. In this paper parametric studies are presented using a 3-DOF model to better understand the effect of the Hamaker constants, suspension pre load and pitch angle on the dynamic stability/instability of the sliders. A stiffness matrix is used to characterize the stability in the vertical, pitch, and roll directions. The fly height diagrams are used to examine the multiple equilibriums that exist for low flying heights. It has been found that the system instability increases as the magnitude of the van der Waals force increases. It has also been found that higher suspension pre load and higher pitch angles tend to stabilize the system.

Experimental and Numerical Analyses of a Head Arm Assembly of a Micro-Drive

2006 ◽  
Vol 326-328 ◽  
pp. 1585-1588
Author(s):  
B.J. Shi ◽  
Dong Wei Shu ◽  
J. Luo ◽  
Q.Y. Ng ◽  
J.H.T. Lau
Keyword(s):  
Finite Element ◽  
Dynamic Properties ◽  
Dynamic Performance ◽  
Hard Disk Drives ◽  
Element Model ◽  
Information Storage ◽  
Experimental Results ◽  
Disk Drives ◽  
Element Simulation ◽  
Important Means

Hard disk drives (HDD) are now the most important means of information storage, and they continue to be made smaller in size, higher in capacity, and lower in cost. The dynamic performance of an HDD has been an increasingly important consideration for its design, as we move forward toward its consumer applications. The dynamic properties of the head arm assembly (HAA) of a micro-drive were investigated using both experimental and numerical techniques. A finite element model for studying the dynamic property of the HAA was created and modified according to the experimental results. Good correlation between the experimental results and those by finite element simulation was achieved.

Air Bearing Slider Simulation and Modeling for Hard Disk Drives with Ultra-Low Flying Heights

2007 ◽  
pp. 314-314
Author(s):  
B. J. Shi ◽  
D. W. Shu ◽  
B. Gu ◽  
M. R. Parlapalli ◽  
C. N. Delia ◽  
...  
Keyword(s):  
Hard Disk Drives ◽  
Hard Disk ◽  
Air Bearing ◽  
Disk Drives ◽  
Simulation And Modeling ◽  
Air Bearing Slider

Design and Dynamics of Flying Height Control Slider With Piezoelectric Nanoactuator in Hard Disk Drives

2006 ◽  
Vol 129 (1) ◽  
pp. 161-170 ◽  
Author(s):  
Jia-Yang Juang ◽  
David B. Bogy ◽  
C. Singh Bhatia
Keyword(s):  
Numerical Study ◽  
Hard Disk Drives ◽  
Hard Disk ◽  
Areal Density ◽  
Flying Height ◽  
Air Bearing ◽  
Disk Drives ◽  
Adhesion Forces ◽  
Surface Design ◽  
Ultrahigh Density

To achieve the areal density goal in hard disk drives of 1Tbit∕in.2 the minimum physical spacing or flying height (FH) between the read/write element and disk must be reduced to ∼2nm. A brief review of several FH adjustment schemes is first presented and discussed. Previous research showed that the actuation efficiency (defined as the ratio of the FH reduction to the stroke) was low due to the significant air bearing coupling. In this paper, an air bearing surface design, Slider B, for a FH control slider with a piezoelectric nanoactuator is proposed to achieve virtually 100% efficiency and to increase dynamics stability by minimizing the nanoscale adhesion forces. A numerical study was conducted to investigate both the static and dynamic performances of the Slider B, such as uniformity of gap FH with near-zero roll over the entire disk, ultrahigh roll stiffness and damping, low nanoscale adhesion forces, uniform FH track-seeking motion, dynamic load/unload, and FH modulation. Slider B was found to exhibit an overall enhancement in performance, stability, and reliability in ultrahigh density magnetic recording.

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