Experimental Evaluation of Stiffness and Damping of Slider-Air Bearings in Hard Disk Drives

1999 ◽  
Vol 121 (1) ◽  
pp. 102-107 ◽  
Author(s):  
Q. H. Zeng ◽  
D. B. Bogy
Keyword(s):  
Dynamic Characteristics ◽  
Dynamic Properties ◽  
Hard Disk Drives ◽  
Hard Disk ◽  
Air Bearing ◽  
Disk Drives ◽  
Air Bearings ◽  
Transient Responses ◽  
Load Beam ◽  
Stiffness And Damping

The system identification method was applied to experimentally investigate the dynamic characteristics of slider-air bearings in hard disk drives. The transient responses of sliders were measured, and the modal frequencies and damping ratios that are directly related to the stiffness and damping of the bearings were obtained by data processing and parameter identification. The dynamic property of a particular advanced air bearing (AAB) slider was measured and compared with simulation results. It was found that, contrary to usual perception, the suspension assembly significantly affects the dynamic characteristics of the air bearings. Contacts between the load beam and the flexure may introduce a larger damping and nonlinear property. The preliminary results also show that the proposed method is robust for experimentally evaluating the dynamic properties of slider-air bearings.

A Numerical Simulation of the Head-Disk Assembly in Magnetic Hard Disk Files: Part I—Component Models

1990 ◽  
Vol 112 (4) ◽  
pp. 593-602 ◽  
Author(s):  
O. J. Ruiz ◽  
D. B. Bogy
Keyword(s):  
Numerical Simulation ◽  
Natural Frequencies ◽  
Hard Disk Drives ◽  
Hard Disk ◽  
Coupled System ◽  
Air Bearing ◽  
Disk Drives ◽  
Air Bearings ◽  
Magnetic Hard Disk ◽  
Component Models

In previous papers the dynamics of air bearing sliders used to carry the read/write transducers in magnetic hard disk files has been studied. These studies are useful in evaluating the steady flying and stability of sliders subjected to various disturbances. They are particularly useful in finding the natural frequencies of the air bearings. However, in hard disk drives the sliders are attached to suspensions, which are highly specialized structures that connect the sliders to the positioning actuators. These suspensions have to be relatively stiff in lateral translation, but very flexible in pitch and roll. This latter feature is accomplished by the gimbal or flexure that connects the slider to the end of the suspension. The suspension-gimbal structure has its own natural frequencies, which can be excited by disturbances such as track seeking and impacting the actuator against the crash stop. In order to study the effect of these structures on the head-disk spacing it is necessary to include them in the numerical simulator. In this two part study such a simulator is developed. In Part I the component parts and their interfaces are modeled. In Part II the numerical simulation of the coupled system is accomplished and the numerical results of several sample simulations are presented and discussed.

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.

Dynamics and control performance of hard disk drives with passive dampers

2004 ◽  
Vol 218 (12) ◽  
pp. 1555-1568 ◽  
Author(s):  
L M Xu ◽  
N Guo ◽  
S Zeng ◽  
R M Lin ◽  
H Du
Keyword(s):  
Dynamic Characteristics ◽  
Transfer Functions ◽  
Hard Disk Drives ◽  
Hard Disk ◽  
Data Access ◽  
Open Loop ◽  
Structure Design ◽  
Disk Drives ◽  
Phase Loss ◽  
Dynamics And Control

The residual vibration is one of the primary mechanical problems that affect the dynamic characteristics of the head actuator assembly in hard disk drives, and the data access speed and positioning resolution. A discrete damping device has been developed to suppress the quasi-rigid-body mode and a reduction of 10 dB in amplitude is shown possible. The servo performance of the head actuator assembly with and without the damping device is presented in this paper, together with the measurement and prediction of the dynamic characteristics. Both closed- and open-loop transfer functions of the plant are measured in the actual operating environment on a servo test stand and compared with the simulation. It is found that the use of passive damping in the structure design allows for a greater margin of error at the crossover frequency since less phase loss results when notch filters are used, thus improving the stability robustness in feedback control.

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.

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