Quock Ng

Operational Shock Simulation of the Head–Disk Assembly of a Small-Form Factor Drive

We created a finite-element model of the head-disk assembly (HDA) of a small-form factor drive. We conducted operational shock simulation and modal analysis with this finite-element model, and investigated the pulsewidth effect of a half-sine acceleration pulse on the shock responses. We found that the umbrella mode of the disk is the dominant mode for operational shock. Numerical results of the pulsewidth effect on the maximum shock responses further confirm the conclusions in a previous work by the authors.

A reliability modeling framework for the hard disk drive development process

Motivated by the fact that the major causes of catastrophic failure in micro hard disk drives are mostly induced by the presence of particles, a new particle-induced failure susceptibility metric, called the Cumulative Particle Counts (CPC), is proposed for managing reliability risk in a fast-paced hard disk drive product development process. This work is thought to represent the first successful attempt to predict particle-induced failure through an accelerated testing framework which leverages on existing streams of research for both particle-injection-based and inherent-particle-generation laboratory experiments to produce a practical reliability prediction framework. In particular, a new testing technique that injects particles into hard disk drives so as to increase the susceptibility of failure is introduced. The experimental results are then analyzed through a proposed framework which comprises the modeling of a CPC-to-failure distribution. The framework also requires the estimation of the growth curve for the CPC in a prime hard disk drive under normal operating conditions without particle injection. Both parametric and non-parametric inferences are presented for the estimation of the CPC growth curve. Statistical inferential procedures are developed in relation to a proposed non-linear CPC growth curve with a change-point. Finally, two applications of the framework to design selection during an actual hard disk drive development project and the subsequent assessment of reliability growth are discussed.

Dynamic Simulation of the Suspension Lift-Tab on a Ramp During the Unloading Process of a Hard Disk Drive

A dynamic model was developed to simulate the interaction between the suspension lift-tab and the ramp of a one-inch load/unload drive by considering the contact and separation states. The indentation depth, bouncing distance, contact force and fractional contact time, which are closely related to the wear and material transfer at the interface, were studied with consideration of the ramp angle, the lateral velocity, and the elastic properties of the ramp.

Power spectrum analysis of the excitation pulse effects in drop test simulation of hard disk drives

A thorough understanding of the dynamic behavior under shock is essential to the development of new generation disk drives. In this paper, the effects of the acceleration pulse shape under conditions of different pulse widths are studied for a given resonant frequency. To emphasize the fundamental aspects of the pulse shape effects, the dynamic system investigated was a single actuator arm without inclusion of the head disk interface or suspension

Air Bearing Slider Simulation and Modeling for Hard Disk Drives with Ultra-Low Flying Heights

As non-traditional application of hard disk drives (HDDs) emerges, their mechanical robustness under shock and other mechanical disturbances during different states are of great concern [1, 2, 3]. Normal drives can not malfunction during the operating state, damage during initial assembly, testing, installation and all unfavorable situations caused by final users. As the areal recording density increases in HDDs, the flying physical spacing between the head/slider and the disk media decreases and the likelihood of head/disk contact during full speed rotation increases. Therefore, the simulation and modeling of the stiffness effect of the air bearing slider with ultra-low flying heights becomes an important issue for the operational shock simulation.

Op-Shock Simulation of the Head Disk Assembly of a Small-Form Factor Drive

Finite element model of the head disk assembly (HDA) of a small-form factor drive was created. Operational shock simulation and modal analysis were conducted with this model. The pulse width effect of a half-sine acceleration pulse on the shock responses was investigated. Three possible approaches were suggested for reducing the shock responses.