Numerical simulation of shock response of disk-suspension-slider air bearing systems in hard disk drives

Abstract

As non-traditional applications of hard disk drives emerge, their mechanical robustness during the operating state is of greater concern. A procedure for simulating the shock responses of a disk-suspension-slider air bearing system is proposed in this paper. A finite element model of the system is developed and modified, and it is used to obtain the dynamic normal load and moments applied to the air bearing slider. The dynamic load and moments are then used as input data for the air bearing dynamic simulator to calculate the dynamic flying attitudes. We obtain not only the responses of the structural components, but also the responses of the air bearing slider. The procedure is convenient for practical application, because it separates the work into two essentially uncoupled steps. It is used to simulate the shock response of a drive. The system modeled is linear if the load dimple of the suspension maintains contact with the slider, but it is non-linear if the dimple separates due to a strong shock. The air bearing has different responses for upward and downward shocks. Slider-asperity contacts occur when a strong shock is applied. IntroductionThe interest in the effects of shock on hard disk drives has come into currency due to the increasingly hostile environments encountered in the usage of the portable computer. As non-traditional applications of hard disk drives emerge, their mechanical robustness under shock and other mechanical disturbances during different states is of greater concern. A typical example is a PC with a disk drive installed on high speed boats. Read/write operation of the drive is frequently aborted because of the shocks caused by wave actions. Normal drives cannot properly function in this kind of environment. The main effects of shock are malfunctions during the operating state, damage during initial assembly, testing, installation into the computer chassis, and all unfavorable situations caused by the final users. There are essentially three approaches for dealing with the shock problems. The first is to design a suitable isolation installation for the disk drives. The second is to design a robust servo control mechanism to prevent read/write error during the shock. The third is to design a robust mechanical system and slider/disk interface. We focus on the third approach. There have been several experimental and simulation studies [1-7] on shock response of the mechanical system and its effects on the head/disk interface. However, most of the published works [1-5] are limited to the non-operating state of the drives, and/or to the component level. As the flying height (FH) continues to decrease and more and stronger disturbances during the operating state are encountered, a better understanding of the effects of the disturbances on the slider/disk interface is required.Two published papers [6, 7] considered shock simulation of disk drives in the operating state. They used quite different approaches. Jiang et al.[6] focused on the rotating disk in their paper. The suspension and slider ...

Design of suspension and swing arm for improved shock resistance in the micro optical disk drives

“…Indeed, it is not just the disk but the head and suspension that risk damage from head slap. Ultimately, head slapping will lead to drive failure of one kind or another (Zeng and Bogy 2002;Aristegui and Geers 2000;Edward 1999). …”

Design and Analysis of Shock and Random Vibration Isolation of Operating Hard Disk Drive in Harsh Environment

“…5). It can be seen that the x-and y-axes GRMS values for failure are higher than the z-axis; from the slider/disk interface point of view, the shock in z-direction has potential to cause more severe damage compared to x-and y-direction [5,9] because this is the direction where the slider will crash onto the disk. Additionally, the suspension (where the slider is attached to; see Fig.…”

“…There are basically three methods to handle the shock and vibration problems in HDD [5]. The first is to design a robust servo control mechanism to prevent read/write head error.…”

Simulation on contact between the droplet and the slider at head-disk interface based on water-hammer pressure model

“…The finite-volume solution of the time-dependence Reynolds equation (Eq. 11) is used to find the response of the air bearing to the contact impact and the dynamic flying attitudes of the slider (Zeng and Bogy 2002).…”