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TECHNICAL PAPERS

# Numerical Simulation of Operational-Shock in Small Form Factor Hard Disk Drives

[+] Author and Article Information
P. Bhargava

Computer Mechanics Laboratory, Department of Mechanical Engineering, University of California, Berkeley, CA 94720puneet@cml.me.berkeley.edu

D. B. Bogy

Computer Mechanics Laboratory, Department of Mechanical Engineering, University of California, Berkeley, CA 94720

J. Tribol 129(1), 153-160 (Apr 24, 2006) (8 pages) doi:10.1115/1.2345403 History: Received July 06, 2005; Revised April 24, 2006

## Abstract

As nontraditional applications of hard disk drives emerge, their mechanical robustness during the operating state is of greater concern. Over the past few years, there has been an increasing application of small form factor ($1in.$ and smaller) hard disk drives in portable consumer appliances and gadgets. A procedure for simulating the operational shock response of a disk-suspension-slider air bearing system is proposed in this paper. A coupled structural-fluid model is presented which can be used to obtain the dynamic response of the slider-suspension-disk system. A commercial program, ANSYS , is used for the finite element models of the suspension and the disk, while the CML dynamic air bearing code is used to concurrently solve the air bearing equations of the system. 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 as well as being highly accurate, since it implicitly solves the structural and air bearing problems simultaneously. It is used to simulate the shock response of a $1in.$ drive. The air bearing has different responses for upward and downward shocks (which are referred to as positive and negative shocks, respectively). For negative shocks, slider-disk contacts are observed to occur when a strong shock is applied, however, the air bearing does not collapse. For positive shocks, we observe a collapse of the air bearing when the shock is sufficiently strong, which is followed by severe contacts between the slider and the disk due to the “head-slap” phenomenon.

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## Figures

Figure 1

Power spectra of disk z response for spinning and stationary disks

Figure 2

Parameterization of disk behavior

Figure 3

The CML shock simulator

Figure 4

Absolute and relative attitude for negative 200G shock

Figure 5

Air bearing and contact forces for negative 200G shock

Figure 6

Absolute and relative attitude for negative 800G shock

Figure 7

Air bearing and contact forces for negative 800G shock

Figure 8

Maximum contact force variation for negative shock

Figure 9

Absolute and relative attitude for positive 200G shock

Figure 10

Air bearing and contact forces for positive 200G shock

Figure 11

Absolute and relative attitude for positive 300G shock

Figure 12

Air bearing and contact forces for positive 300G shock

Figure 13

Absolute and relative attitude for positive 500G shock

Figure 14

Air bearing and contact forces for positive 500G shock

Figure 15

Maximum air bearing force for positive shock

Figure 16

Maximum contact force variation for positive shock

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