Aplicación de modelos viscoelásticos fraccionales para la estimación del factor de pérdidas a distintas frecuencias de casquillos silentblock en base a ensayos de relajación en máquinas universales de tracción

Abstract

Silentblocks are rubber bushings used to improve the acoustic and vibratory behavior of machines. The macroscopic properties that characterize the damping capability of these parts are the absolute value of the dynamic stiffness or complex stiffness, and the loss factor, both of them estimated in the nominal frequency range of the design parameters of each silentblock. This investigation aimed to establish a methodology to estimate the loss factor, and its dependency on the frequency, by a single relaxation test. For that, different classical viscoelastic models were used, such as Zener model or Generalized Maxwell-Wiechert model with two branches, and they were compared with the capability of more complex models such as their alternatives with fractional derivatives. This numerical analysis, and its experimental testing verification, verified that the fractional model showed higher capability in the estimation of the loss factor for a wide frequency range based on a single relaxation test. This would allow establishing, for silentblocks characterization, alternatives to dynamic harmonic tests based on relaxation tests in a universal tensile machine.