Geonyup Lim

Design Modifications to Improve the Antishock Performance of a Stamped Base for a 2.5-in HDD

This paper presents a modified design for a stamped base for a 2.5-in hard disk drive (HDD). A stamped base is a thinner thickness and lower stiffness than a die-casting base. To improve shock performance of the stamped base, the finite element (FE) model of the HDD is constructed. Then, the FE model was verified by modal analysis. Drop test was performed to confirm the shock simulation model. Parametric analysis was used to identify the key parameters for the shock performance which were the base thickness, rib shape, number of ribs, and reinforcement. The correlation between the relative displacement and natural frequency of the HDD was investigated for each parameter. The dominant parameter was identified and applied to the FE model of the stamped base. The modified stamped-base model was then evaluated under nonoperational shock conditions.

Analysis of slider dynamics induced by various ramp-disk contact situation in hard disk drive

This research investigates to analyze the effect of ramp-disk gap to slider dynamics in operational shock situation. To investigate the effect, simulations is conducted with verified finite element model include various ramp-disk gap. The slider dynamics is more unstable in bigger difference of ramp-disk gap model.

Operational Shock Analysis for 2.5-in Multi-Disk HDD Considering Ramp–Disk Gap Irregularity

With an increased mobility, hard disk drives (HDDs) now use ramp load/unload technology, and multiple disks are used to increase the data capacity. This can result in contact between the ramp and the disks, which negatively affects the slider dynamics under operational shock conditions. There are several types of ramp–disk contact, such as simultaneous, successive, and single contact, and these depend on the distance between the ramp and each disk in a multi-disk HDD. This paper examines the effect of ramp–disk contact on the slider dynamics using a transient shock analysis. The ramp–disk contact affects the head stack assembly bending mode and slider dynamics. The effect of irregular gaps between the disks and adjacent ramp on the slider dynamics is analyzed with the ramp–disk contact force. The simulation shows that the gap irregularity between the ramp and each disk should be as small as possible to improve the stability of the slider dynamics.

Analysis of the Influence of the Ramp and Disk Dynamics on the HDI Response of 2.5-in Hard Disk Drive to a Shock

Operational shock (op-shock) analysis has been developed to consider the dynamics of components of a hard disk drive (HDD). Op-shock simulation uses simplified models. However, the dynamics of the components affect the head–disk interface (HDI) response, especially the disk curvature and ramp–disk contact. This paper investigated the effect of the dynamics of HDD components on the HDI response. As the HDD is more sensitive to external shock and vibration, the effects of the dynamics of HDD components need to be considered for accurate op-shock analysis. The ramp–disk contact is an important factor in an op-shock simulation, because ramp–disk contact and disk deformation occur during the shock. Therefore, this op-shock simulation modeled the ramp–disk contact and considered the disk curvature. To obtain an accurate result, a two-way coupled method was used to investigate the HDD dynamic response during op-shock. Using the op-shock model, the fluid-structure coupling effect was investigated and compared with a decoupled model that used linear springs to replace the air bearing. Then, we investigated the effect of the ramp–disk contact and disk curvature on the HDI response during a shock.

Analysis of dynamic response of hard disk drive according to air bearing stiffness

The accurate shock analysis is required because the possibility of the head-disk contact is increased. Thus, two-way coupled model is developed to investigate the nonlinear cases such as lift-off and contact. The two-way coupling model can consider the effect of fluid-structure. In this paper, the effect is investigated and compared with the decoupled model. First, the dynamics of head disk interface (HDI) during op-shock are investigated with developed two-way coupled method. Then, we classify and investigate the dynamics of HDI after head-disk contact.

A Flying Stability of the Slider With Damaged DLC Layer by Confined Optical Energy in TAMR System

This research investigates to analyze the effect of laser of thermally assisted magnetic recording system on diamond like carbon (DLC) layer of slider. We investigated a damaged DLC layer of slider with laser spot-induced damage and analyze the effect of the damaged DLC layer in slider dynamics. The damaged DLC layer resulted in change of flying height and air bearing stiffness pressure.Copyright

Efficient Air Bearing Modeling for Operational Shock Analysis in 2.5-Inch HDD

As use of mobile computing devices has spread rapidly, it is very important to accurately analyze and predict anti-shock performance of the HDD system. In this paper, we proposed an efficient air bearing modeling method to analyze op-shock performance for the in 2.5-inch HDD system with ramp-disk contact behavior. We first constructed the decoupled approach method using linear air bearing springs in finite element method and used the Lagrange multiplier method for contact modeling between disk and ramp. With the constructed finite element model, the effect of linear air bearing stiffness was investigated in the decoupled method. We found that air bearing stiffness affects the behavior of the slider dominantly in the HDDs system with ramp-disk contact. Based on the numerical results, the advanced method able to efficiently reflect air bearing characteristics was proposed and evaluated.Copyright

Analysis of dynamic characteristic applying frame on stamped base in 2.5 inch hard disk drive

HDD has been easily exposed to the external shock and vibration because HDD has to apply to mobile devices. Therefore, the stiffness of base has been the important factors for the design of HDD. To improve the stiffness of base, the frame was applied to the base. First, the finite element model of the base was constructed. Then, the FE model was verified by modal analysis. Drop test was performed to confirming the shock simulation model. The dynamic characteristic of original base which is verified is compared with the base which is applied the frame through modal analysis and shock analysis.

Optimized Design of HDD Stamped Base to Increase Stiffness

For the production method, stamp base is increasing the market share. But also, by the manufacturing method, stiffness of the stamp base is small. Many studies have been carried out in order to increase the stiffness of the stamp base. In this study, we optimally designed according to the position of bolting using a screening method in order to increase the stiffness base. After establishing a simulation model, the maximum deformation and frequency of the first mode based having relevance with stiffness of the base, were optimized. There for, it was possible to expect of increasing the stiffness of the stamp base.

Experimental investigation of TD characteristics of a flying head slider in the near-contact region

Head Disk Interface (HDI) in a Hard Disk Drive (HDD) has decreased to achieve high areal density. Thus, the contact between a slider and a disk becomes more important. The contact between the slider and the disk can cause severe wear and damage of both the slider and the disk. Especially, Touch Down (TD) that the contact occurs continuously and repeatedly is extremely dangerous. Therefore, it is necessary to analyze the unstable bouncing vibration of the slider in head-disk interface. In this paper, we investigate the characteristic and causes of the Touch Down.