Nonlinear fluid forces in cylindrical squeeze films. part I: Short and long lengths

Using three approximation methods, nonlinear models have been derived for s hort and long cylindrical squeeze films with arbitrary inner cylinder motio ns. Elliptical and parabolic velocity profiles are employed in the derivati on in order to determine the effects of the choice of velocity profile. The only differences in the final squeeze film equations, due to the three app roximation methods and the two velocity profiles, are in the four constant coefficients. Each term in the squeeze him equations is a nonlinear functio n of cylinder position. Comparing the present nonlinear expressions with ex isting models for short cylindrical squeeze films shows that the force term s are either exactly the same or have the same trends with instantaneous ec centricity values. For long cylindrical squeeze films, the present expressi ons have some force terms which are essentially the same as in other studie s, while other force terms show variations with position which are very dif ferent from a previously published study. (C) 2001 Academic Press.