Study of flow induce vibration inside 3.5 inch hard disk drives.

Abstract

This study focused on flow induced vibration of head stack assembly (HSA) in a 3.5 inch hard disk drive with
5 disks and 10 read/write heads. We studied the effects of air flow on gimbal flex and resonance on arm. The
comparison of vibrations on slider between the normal model and the experiment has been done for verifying the model. The peaks of frequency in experiment match the normal model at 1,040 1,320 and 1,400 Hz
respectively. After that, the RNG K-ε turbulence model was used to determine the turbulent air flow of 7,200
rpm hard disk drive. The comparison between the normal model and the model with spoiler was investigated
by using, computational fluid dynamics software (ANSYS and FLUENT). The results shown velocity
magnitudes at the arm were decreased by 0.725 - 57.689 % and pressure dropped by 74.028 - 87.222 %.
The velocity magnitudes at the gimbal flex were decreased by 5.522 - 14.291 % and pressure dropped by
48.440 - 82.947 %. The peak of vibrations on arm and gimbal flex was occurred at the frequency 1200 Hz.
The model with spoiler could reduce vibration at arm by 2.56 - 95.601 % and reduce vibration at gimbal flex
by 4.065 - 95.503 %. In the conclusion, the model with a spoiler could decrease the vibration at all surface of
the arm and gimbal flex due to the velocity and pressure reduction[1][4].