Coupling Model for Viscoelastic Sandwich Beams Used for Vibration Control

Resumo

Dynamic neutralizers are simple devices used to minimize the levels of vibration and noise radiated
from a mechanical structure in a certain frequency range. They operate by inserting a high mechanical impedance
in the region of interest, applying reaction forces, and dissipating vibratory energy. Composite sandwich beams
with viscoelastic materials are used to control vibration in structures with high modal density, such as plates,
slender buildings and electrical transmission lines due to their dynamic characteristics. In addition to the high
damping factor, the use of these neutralizers with multiple degrees of freedom (MDOF) is favorable for the control
of these structures, especially when working in a wide frequency band. This study presents a novel coupling model
using angular and translational degrees of freedom between the structure to be controlled (primary system) and
the MDOF auxiliary system attachment point. The dynamic behavior of the MDOF sandwich beam under study is
modeled using the commercial finite element software ANSYS®. Then, in the Matlab® software, the compound
system is assembled using the primary system modal parameters coupled to the dynamic behavior of the sandwich
beam using translational and rotation equivalent springs. The finite element method was validated with
experimental data of a single degree of freedom viscoelastic neutralizer. The numerical and experimentally
dynamic behavior showed an excellent approximation. Additionally, the transfer functions of a fixed-free beam
with a sandwich beam attached to the free end are analyzed studying the coupling of translational and rotation
DOF. For MDOF neutralizers, the coupling model accuracy is extremely important to ensure the proper design of
the auxiliary system physical parameters for vibration control.