Vibration of rotating disk/spindle systems with flexible housing/stator assemblies

The subject of study in this paper is a rotating spindle carrying multiple flexible disks mounted on a flexible housing/stator assembly through ball bearings or hydrodynamic bearings. The disk/spindle system is subjected to prescribed force excitations, and the housing/stator assembly is subjected to prescribed linear and angular base excitations. This paper has two specific goals. The first goal is to derive linearized equations of motion governing free and forced vibration of the spindle/housing system using a Lagrangian formulation. The second goal is to verify the mathematical model through calibrated experiments. Theoretical predictions of natural frequencies agree well with experimental measurements within 5% of difference for spindle motors using ball bearings. Numerical simulations on spindle motors with hydrodynamic bearings indicate that base flexibility could lead to significant spindle vibration.