Performance Characteristics of the Magnetic Constrained Layer Damping

A Baz,S Poh

doi:10.1155/2000/658593

Abstract

A new class of surface damping treatment is proposed to provide effective means for attenuating undesirable structural vibrations. The proposed treatment relies in its operation on the use of smart damping treatments which consist of integrated arrays of constrained visco-elastic damping layers that are controlled passively by a specially arranged network of permanent magnets. The interaction between the magnets and the visco-elastic layers aims at enhancing the energy dissipation characteristics of the damping treatments. In this manner, it would be possible to manufacture structures that are light in weight which are also capable of meeting strict constraints on structural vibration when subjected to unavoidable disturbances.Emphasis is placed here on introducing the concept and the basic performance characteristics of this new class of smart Magnetic Constrained Layer Damping (MCLD) treatments. Comparisons are also presented with conventional Passive Constrained Layer Damping (PCLD) in order to determine the merits and limitation of the MCLD treatments.

Highlights

Passive Constrained Layer Damping (PCLD) treatments have been successfully utilized, for many years, to damp out the vibration of flexible structures ranging from simple beams to complex space structures [9]
In the Passive Constrained Layer Damping with Shunted Networks (PCLD/SN), the augmentation results from the energy dissipation in the shunted electric circuitry whereas in the Active Constrained Layer Damping (ACLD) and the APDC treatments, the augmentation is attributed to the enhanced shear and compressional deformations of the visco-elastic layers, respectively
The PCLD/SN, ACLD and APDC treatments have proven to be very successful in damping out structural vibration, they require the use of piezoelectric films, amplifiers and control circuits

Summary

Introduction

Passive Constrained Layer Damping (PCLD) treatments have been successfully utilized, for many years, to damp out the vibration of flexible structures ranging from simple beams to complex space structures [9]. The undeflected configuration of the structure/PCLD system is shown in Fig. 1(a) whereas Figure 1(b) shows the deflected configuration under the action of an external bending moment M e Due to such loading, shear strains of γT and γB are induced in the top and bottom viscoelastic layers respectively. It is not beneficial to arrange the magnetic layers in repulsion because of their low energy dissipation characteristics This is in spite of the fact that such MCLD arrangement induces in-plane tensile loads in the base structure which tend to enhance its stiffness. Increasing the shear strain γ results in significant increase in the energy dissipated in the viscoelastic core Such improved damping exists in the PCLD/SN, ACLD and APDC treatments but at the expense of the complexities associated with the use of piezo-sensors, piezo-actuators, control circuitry and/or external energy sources. In what follows the improved damping characteristics of the MCLD are demonstrated in comparison with the performance of PCLD treatments

Materials

Experimental set-up

Full treatment with magnets in base and in constraining layers

Partial treatment with magnets in base and in constraining layers

Conclusions