DYNAMIC ANALYSIS OF VISCOELASTIC-FLUID DAMPERS

A solution methodology is presented for computing the dynamic stiffnesses in all vibration modes of viscoelastic-fluid dampers with mechanical properties that depend strongly on both frequency and temperature. The method of reduced variables is introduced to construct the master curves of the dynamic modulus of the fluid at some reference temperature from experimental data at different temperatures. Three generalized-derivative (fractional and complex order) constitutive models are proposed to approximate the dynamic modulus of the polybutane fluid over a wide frequency range. The complex parameters of the proposed models are obtained by finding the best fitting of the master curves. The solution of the problem is obtained by transforming the constitutive and balance equations in the Laplace domain, and developing a boundary-element formulation. The resulting method is applied in the prediction of the mechanical properties of a damper containing the polybutane viscoelastic fluid. Results using the three proposed generalized-derivative constitutive models are compared against experimental data.