INVESTIGATION OF HEAD-DISK INTERFACE AND UNLOADING PROCESS IN HDD WITH AN EFFICIENT SCHEME

2012 ◽  
Vol 19 ◽  
pp. 311-319
Author(s):  
HEJUN DU ◽  
YAN LIU
Keyword(s):  
Hard Disk Drives ◽  
Element Model ◽  
Disk Drives ◽  
Disk Interface ◽  
Efficient Scheme ◽  
Suspension Stiffness ◽  
Suspension Model ◽  
Micrometer Scale ◽  
Parameter Values ◽  
Analytical Expressions

An efficient scheme was developed to analyze head-disk interfaces (HDIs) in hard disk drives. HDIs were studied by decoupling the nanometer scale variations of the air bearings and the micrometer scale changes of the suspensions. The nonlinear variations of the air bearing forces and moments were described with analytical expressions obtained from a surface fitting scheme. Combined with a 3 degree of freedom (DOF) suspension model whose parameters were estimated from a comprehensive finite element model, the historical behaviors of a subambient slider during an unloading process can be obtained in a very short computation period, thus providing a way of exploring a large number of parameter values of the suspension stiffness matrix.

Investigation of HDD Ramp Unloading Processes with an Efficient Scheme

2011 ◽  
Vol 3 (6) ◽  
pp. 716-728 ◽  
Author(s):  
Yan Liu ◽  
Hejun Du
Keyword(s):  
Hard Disk Drives ◽  
Scale Model ◽  
Air Bearing ◽  
Disk Interface ◽  
Efficient Simulation ◽  
Lumped Parameter ◽  
Efficient Scheme ◽  
Three Stages ◽  
Suspension Model ◽  
Simulation Scheme

AbstractRamp load/unload (L/UL) mechanisms are widely used to rest sliders in hard disk drives (HDDs). Loading/unloading a slider swiftly and smoothly is crucial in a HDD design. A novel, efficient simulation scheme is proposed to investigate the behaviors of a head disk interface (HDI) in ramp unloading processes. A dual scale model is enabled by decoupling the nano-meter scale change of an air bearing and the micro- or milli-meter scale deformation of a suspension. A modified Reynolds equation governing the air bearing was solved numerically. The slider design was characterized with performance functions. Three stages in an unloading process were analyzed with a lumped parameter suspension model. Key parameters for the model were estimated with a comprehensive finite element suspension model. Finally, simulation results are presented for a commercial HDI design.

A Performance Surface Method for Characterizing the Nonlinear Air Bearing Forces and Moments With Application to the Unloading Process

2008 ◽  
Author(s):  
Yan Liu ◽  
Shao Wang
Keyword(s):  
Computation Time ◽  
Air Bearing ◽  
Fitting Procedure ◽  
Moment Functions ◽  
Efficient Scheme ◽  
Suspension Stiffness ◽  
Suspension Model ◽  
Performance Surface ◽  
Parameter Values ◽  
Flying Attitude

An efficient scheme was developed to analyze the dynamics of a magnetic head slider during the unloading process. The nonlinearity of the air bearing forces and moments was described by analytical expressions obtained from a surface fitting procedure. Combined with a dual-scale suspension model, the force and moment functions determined can be used to obtain the instantaneous flying attitude of the slider and the unloading time with a very short computation time, thus providing a way of exploring a large number of parameter values of the suspension stiffness matrix.

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.

Optimization of Air Bearing Contours for Shock Performance of a Hard Disk Drive

2003 ◽  
Author(s):  
Eric M. Jayson ◽  
Frank E. Talke
Keyword(s):  
Hard Disk Drive ◽  
Hard Disk Drives ◽  
Hard Disk ◽  
Disk Drive ◽  
Element Model ◽  
Time Dependent ◽  
Air Bearing ◽  
Disk Interface ◽  
Shock Response ◽  
Shock Event

Hard disk drives must be designed to withstand shock during operation. Large movements of the slider during shock impulse can cause reading and writing errors, track misregistration, or in extreme cases, damage to the magnetic material and loss of data. The design of the air bearing contour determines the steady state flying conditions of the slider as well as dynamic flying conditions, including shock response. In this paper a finite element model of the hard disk drive mechanical components was developed to determine the time dependent forces and moments applied to the slider during a shock event. The time dependent forces and moments are applied as external loads in a solution of the dynamic Reynolds equation to determine the slider response to a shock event. The genetic algorithm was then used to optimize the air bearing contour for optimum shock response while keeping the steady flying conditions constant. The results show substantial differences in the spacing modulation of the head/disk interface after a shock as a function of the design of the air bearing contour.

Operational Shock Response of Ultrathin Hard Disk Drives

2014 ◽  
Author(s):  
Shengkai Yu ◽  
Jianqiang Mou ◽  
Wei Hua ◽  
Weidong Zhou ◽  
Chye Chin Tan
Keyword(s):  
Hard Disk Drives ◽  
Hard Disk ◽  
Element Model ◽  
System Level ◽  
Disk Drives ◽  
Disk System ◽  
Shock Response ◽  
Shock Simulation ◽  
Resistance Performance ◽  
Operational Shock

Operational shock is one of key challenges for designing the ultrathin mobile hard disk drives (HDDs) due to the reduced thickness of mechanical components and their stiffness. Some simplifications in the conventional methods for operational shock simulation are not valid. In this paper, a method for system level modelling and simulation of operational shock response of HDDs has been proposed by coupling the structural finite element model of the HDD and the air bearing model. The dynamic shock response of the head-disk system in a 5 mm ultrathin HDD design is investigated. The effects of drive base stiffness, disk-ramp contact, disk spinning and disk distortion have been studied. The results reveal that the drive base deformation and ramp contact are critical for the operational shock resistance performance of ultrathin drives.

On the Touchdown-Takeoff Hysteresis Observed at the Head-Disk Interface in Hard Disk Drives

2005 ◽  
Author(s):  
Rohit P. Ambekar ◽  
David B. Bogy
Keyword(s):  
Experimental Approach ◽  
Hard Disk Drives ◽  
Hard Disk ◽  
Intermolecular Forces ◽  
Disk Drives ◽  
Head Disk Interface ◽  
Contributing Factors ◽  
Factors Affecting ◽  
Disk Interface

The touchdown-takeoff velocity hysteresis observed in hard disk drives during CSS or L/UL tests is analyzed using an experimental approach. Tests similar to L/UL were conducted for different slider-disk combinations at different humidities. Factors affecting the touchdown and takeoff velocity were identified on the basis of their domain of operation. It is concluded that the intermolecular forces and meniscus forces are contributing factors to hysteresis, which is also influenced by disk topography and slider dynamics.

Numerical Analysis of Microwaviness-Excited Vibrations of a Flying Head Slider at Touchdown

2017 ◽  
Author(s):  
Kyosuke Ono
Keyword(s):  
Adhesion Force ◽  
Hard Disk Drives ◽  
Force Model ◽  
Air Bearing ◽  
Single Degree Of Freedom ◽  
Disk Interface ◽  
Head Slider ◽  
Bearing Stiffness ◽  
Bearing Force ◽  
Parameter Values

As an extension of the study presented in ISPS 2016, vibration characteristics of a commercially used head slider in hard disk drives at touchdown are analyzed by using a single degree-of-freedom (DOF) slider model, improved asperity adhesion force model, and air-bearing force model. Using parameter values at the head/disk interface, the total interfacial force was evaluated for various air bearing stiffness ratios r. Microwaviness (MW)-excited slider vibration was simulated near the boundary of instability onset (r = 2.4), and slight instability conditions at r = 2. It was found that the simulated results at r = 2.4 and 2 agree well with the touchdown vibrations of actual slider at ID and MD, respectively. The possibility of surfing recording is discussed.

Boundary Effect on Particle Motion in the Head Disk Interface

2007 ◽  
Author(s):  
Nan Liu ◽  
David B. Bogy
Keyword(s):  
Drag Force ◽  
Particle Motion ◽  
Boundary Effect ◽  
Hard Disk Drives ◽  
Areal Density ◽  
Air Bearing ◽  
Disk Drives ◽  
Head Disk Interface ◽  
Bearing Surface ◽  
Disk Interface

Simulation of particle motion in the Head Disk Interface (HDI) helps to understand the contamination process on a slider, which is critical for achieving higher areal density of hard disk drives. In this study, the boundary effect—the presence of the slider and disk—on particle motion in the HDI is investigated. A correction factor to account for this effect is incorporated into the drag force formula for particles in a flow. A contamination criterion is provided to determine when a particle will contaminate a slider. The contamination profile on a specific Air Bearing Surface is obtained, which compares well with experiments.

Contact Take-Off Characteristics of Proximity Recording Air Bearing Sliders in Magnetic Hard Disk Drives

1999 ◽  
Vol 121 (4) ◽  
pp. 948-954 ◽  
Author(s):  
Yong Hu
Keyword(s):  
Hard Disk Drives ◽  
Air Bearing ◽  
Disk Drives ◽  
Head Disk Interface ◽  
Taper Angle ◽  
Wear Factor ◽  
Disk Interface ◽  
Partial Contact ◽  
Magnetic Hard Disk ◽  
Wear Law

A partial contact air bearing model and Archard’s wear law are used to investigate the air bearing and wear characteristics of proximity recording sliders during a take-off process. The air bearing pitch torque, pitch and contact force are used to characterize the contact take-off process. In addition, the wear factor derived from the Archard’s wear law is employed to measure the take-off performance. The results indicate the existence of two distinct take-off stages: a period of rapidly increasing pitch preceding a relatively steady take-off event. The proper range of taper angle and step height, which produce a rapid initial pitch increase and steady subsequent take-off as well as less wear in the head/disk interface, are determined through simulation. While the simulation results demonstrate the negligible effect of crown height on the rate of the initial pitch increase, larger crown values are shown to yield higher pitch and smaller wear in the head/disk interface during the take-off process. In summary, the partial contact air bearing simulation and the wear factor calculation of the take-off process, developed in this study, offers a fast and accurate analytical tool to optimize ABS design for the fast take-off performance.

Sign in / Sign up

Export Citation Format

Share Document