ANALYTICAL MODEL OF VISCOELASTIC FLUID DAMPERS

An analytical approximate constitutive relation is derived for a form of fluid damper, which exhibits viscoelastic behavior. The damper is u sed for vibration isolation of piping systems and industrial equipment , as well as for vibration and seismic isolation of building structure s. The damper consists of an open pot, filled with highly viscous flui d, and a piston that moves within the fluid. The analytical solution r elates the damping constant of the unit at vanishingly small frequenci es with the material constants of the fluid used in the damper and the geometric characteristics of the damper. With the determination of th e damping constant, a macroscopic model may be constructed that descri bes the damper behavior over a large frequency range. The other parame ters of the macroscopic model arc identical to those in the correspond ing constitutive relation of the damper fluid. The results of the anal ytical solution are in very good agreement with experimental data and with numerical solutions based on boundary-element analysis.