The step jump method is used to characterize the stiffness and damping of f
lat-faced gas lubricated squeeze film dampers. Analytic solution of a linea
rized form of the isothermal and compressible Reynolds equation yields clos
ed form expressions for the step and frequency responses of the gas film. R
esults from the step jump method obtained both analytically and numerically
are shown to be good approximations of the gas film stiffness and damping.
A Prony series is proven to be an effective constitutive model capable of
representing the stiffness and damping of the gas film in both the time and
frequency domains in analytic form. Using the analytic constitutive model,
closed form solutions for the motion of squeeze film dampers are now possi
ble.