Study on the geometrical characteristics in the natural modes of vibration of a swing arm

Byung Ju Dan, Yong Je Choi

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It has been recognized that the lowest mode of vibration, mainly caused by bearing stiffness, plays an important role in the design of a swing arm used in a hard disk drive. In this paper, assuming that a pivot bearing can be modeled by linear springs and dampers and that the swing arm is a rigid body supported by them, the swing arm's natural modes of planar vibration have been studied with the screw theory. With the use of the congruence transformation that diagonalizes the stiffness matrix and the interpretation of the natural modes as rotations at vibration centers for planar vibration, the coordinates of vibration centers have been expressed by cubic equations in terms of the stiffness ratio and the location of the mass center of the swing arm. The root-locus technique has been applied to the cubic equations in order to investigate the influences of the stiffness ratio and the location of the mass center on the natural modes. With the use of the root-locus analysis of vibration centers, a simple geometrical design methodology to reduce or to eliminate any undesirable effect of a particular natural mode on the forced responses of a swing arm has been suggested. A numerical example is used to illustrate the design method.

Original languageEnglish
Pages (from-to)339-349
Number of pages11
JournalJournal of Information Storage and Processing Systems
Issue number4
Publication statusPublished - 1999 Dec 1


All Science Journal Classification (ASJC) codes

  • Engineering(all)

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