186. NUMERICAL ANALYSIS OF HARD DISK DRIVE TRIBOLOGY
Name: Hao Zheng
Grad Year: 2012
Hard disk drives (HDDs) must be designed to be resistant to shock in order to prevent undesired wear at the head/disk and dimple/gimbal interface. During operation of a hard disk, a normal force is exerted by the suspension on the gimbal. When an external shock is applied to the HDD, the normal force causes local plastic deformation and may lead to fretting wear at the dimple/gimbal interface. This fretting wear is likely to generate wear particles and can be one of the reasons for the failure of a hard disk drive.
In addition, even during normal hard disk drive operation, slider/disk contacts can occur. These contacts can lead either to surface damage or magnetic erasure, or to both of them. The possible reason of magnetic erasure may be related to magnetostriction and thermal flash temperature effects. The exact mechanism of this type of erasure is not fully understood yet, especially in the case of perpendicular recording.
In this study, a finite element model of a HDD is built to study the shock response of the head gimbal assembly. The results from the FE model can be then used as the normal force input for the dimple/gimbal interface modeling and the input for the velocity for the slider/disk contact modeling.
In the dimple/gimbal interface model, the dimple is modeled as a hollow sphere while the gimbal is modeled as a deformable flat. Contact load, contact area and stress distribution at the dimple/gimbal interface are determined for a range of normal force in the elastic-plastic regime of deformations.
In the slider/disk contact model, the corner of the slider is modeled as a solid sphere impacting the deformable disk surface. The time dependent stress distribution is presented as a function of impact velocity, and the effect of the temperature rise during contact is studied on the magnetic erasure.