A Study of Cross-Width Variations in the Two-Dimensional Foil Bearing Problem

Abstract

The foil bearing problem, common to magnetic tape recording, is modeled through numerical simulation. The emphasis is on the effects of cross-width changes in the system parameters. Air lubrication is modeled using the Reynolds equation including the first-order slip correction terms and compressibility. A segmented structural model is introduced for the tape displacements where the tape is modeled as a cylindrical shell in the wrap zone and as a plate in the straight segments between the guide pins and the tangency points. Tape inertia and transport effects are included by using the material time derivative of the displacements. An explicit time integration method is used for the tape equation in order to obtain a faster transient coupling algorithm. The Reynolds equation is solved with the alternating direction implicit (ADI) integration method. The effects of axial tape tension, guide shape variations and the tape width on the steady-state tape-guide separation are investigated. It is shown that small axial variations on the parameters mentioned can lead to important and unintended variations in tape-guide separation.