A STUDY OF CROSS-WIDTH VARIATIONS IN THE 2-DIMENSIONAL FOIL BEARING PROBLEM

The foil bearing problem, common to magnetic tape recording, is modele d through numerical simulation. The emphasis is on the effects of cros s-width changes in the system parameters. Air lubrication is modeled u sing the Reynolds equation including the first-order slip correction t erms and compressibility. A segmented structural model is introduced f or the tape displacements where the tape is modeled as a cylindrical s hell in the wrap zone and as a plate in the straight segments between the guide pins and the tangency points. Tape inertia and transport eff ects are included by using the material time derivative of the displac ements. An explicit time integration method is used for the tape equat ion in order to obtain a faster transient coupling algorithm. The Reyn olds equation is solved with the alternating direction implicit (ADI) integration method. The effects of axial tape tension, guide shape var iations and the tape width on the steady-state tape-guide separation a re investigated. It is shown that small axial variations on the parame ters mentioned can lead to important and unintended variations in tape -guide separation.