Stability Analysis of a 2” Floppy Disk Drive System and the Optimum Design of the Disk Stabilizer

This paper presents a study on the stability of a 2″ floppy disk drive system. A design method of the disk stabilizer that makes the rotating disk stable is presented. The stabilizer and the read/write head are both modeled by springs with high axial stiffnesses. The stiffness of the air film surrounding the disk is determined from the Navier-Stokes equation as a function of the flow rate of the air within the disk jacket. The solution is obtained by using the multi-modal expansion approximation and applying the Galerkin method to the resulting equations. Numerical results show that the 2″ floppy disk rotating at 3600 rpm is unstable without the stabilizer. Further, it is shown that the stability of the disk is much affected by the geometrical configuration of the stabilizer attached to the rotating disk. A stabilizer that contacts the disk at four points was found quite effective in stabilizing the 2″ disk working at 3600 rpm.