Influence of permanent magnets on vibration characteristics of a partially covered sandwich cantilever beam

Abstract

The shear strains of viscoelastic damping layers resulting from the attraction arrangement magnets on the constraining layers root are higher than those of the conventional passive constrained layer damping treatment (PCLD). Therefore, significant improvement of damping characteristics can be achieved by using the new class of magnetic constrained layer damping treatment (MCLD). This paper presents an analytical modelling to elucidate vibration attenuation mechanism of the MCLD. It is shown that the variation amplitude of viscoelastic damping layers shear angle at the root where permanent magnets are fitted is relatively high, producing relatively high dynamic magnetic force compared to the maximal force on the constraining layers. The dynamic magnetic force is strong enough to reduce the elastic potential energy of the constraining layers and the primary layer and enhances the dissipation energy of the damping layers. The rise in the ratio of the dissipation energy to the total system energy per cycle suppresses the resonance peak. Furthermore, influences of permanent magnets on resonance peaks for the first several modes under different physical and geometrical properties are evaluated. Such evaluations are used to determine the merits and limitations of the MCLD treatment and develop design guidelines.