Passive Damping of Spinning Disks

Abstract

An investigation of the application of constrained-layer damping to computer disk drives is pre sented. Nine constrained-layer disks were manufactured and tested to determine their modal parameters and variations. The eigenvalue realization algorithm was used to extract the natural frequencies and damping ra tios from the nine constrained-layer damped disks and from four solid aluminum disks. These results provide damping values that will be useful in future stability analyses of spinning disks that include damping. Finite element models were developed and used to calculate natural frequencies and damping ratios for the damped disks. The numerical results are compared to the measured values. The natural frequencies are predicted to within 8%, and the damping ratios are predicted to within 35% of the experimentally determined values. The finite element model provides a method to obtain damping values and natural frequencies for different layer thicknesses for future studies. The results also give an indication of the accuracy expected from the finite el ement results. Finally, the experimental results from spinning the constrained-layer damped disks in a disk drive assembly are presented. The results show that the constrained-layer damping dramatically reduces the transverse vibrations of the spinning disks in the present configuration.