Engineering and Computer Science Faculty Publications

High Frequency, Multi-axis Dynamic Stiffness Analysis of a Fractionally Damped Elastomeric Isolator Using Continuous System Theory

Document Type

Article

Publication Date

2-17-2017

Journal Title

Journal of Sound and Vibration

ISSN

0022-460X

Volume

389

First Page

468

Last Page

483

DOI

https://doi.org/10.1016/j.jsv.2016.11.025

Abstract

A spectral element approach is proposed to determine the multi-axis dynamic stiffness terms of elastomeric isolators with fractional damping over a broad range of frequencies. The dynamic properties of a class of cylindrical isolators are modeled by using the continuous system theory in terms of homogeneous rods or Timoshenko beams. The transfer matrix type dynamic stiffness expressions are developed from exact harmonic solutions given translational or rotational displacement excitations. Broadband dynamic stiffness magnitudes (say up to 5 kHz) are computationally verified for axial, torsional, shear, flexural, and coupled stiffness terms using a finite element model. Some discrepancies are found between finite element and spectral element models for the axial and flexural motions, illustrating certain limitations of each method. Experimental validation is provided for an isolator with two cylindrical elements (that work primarily in the shear mode) using dynamic measurements, as reported in the prior literature, up to 600 Hz. Superiority of the fractional damping formulation over structural or viscous damping models is illustrated via experimental validation. Finally, the strengths and limitations of the spectral element approach are briefly discussed.

Keywords

High frequency vibration isolator, Spectral element method, Continuous system theory, Viscoelastic materials, Fractional damping

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