Active and Passive Vibration Damping

6Energy Dissipation in Damping Treatments

6.1 Introduction

The energy dissipation characteristics of various types of viscoelastic damping treatments are presented for rods, beams, and plates. Passive damping treatments in constrained and unconstrained configurations are considered. Also, Active Constrained Layer Damping (ACLD) treatments, consisting of viscoelastic cores constrained by active piezoelectric layers, are presented as effective means for enhancing the damping characteristics and compensating for the performance degradation of passive treatments.

6.2 Passive Damping Treatments of Rods

The energy dissipation characteristics of structures treated with passive damping treatments in constrained and unconstrained configurations are considered in this section.

6.2.1 Passive Constrained Layer Damping

Figures 6.1 and 6.2 show drawings of the passive constrained layer damping (PCLD) treatment. It is assumed that the thicknesses of the constraining and viscoelastic layers are very small compared to that of the base structure. Hence, the bending effects are negligible, the constraining layer is subjected to longitudinal strains only, and the viscoelastic core is subjected to shear only. It is also assumed that the longitudinal stresses in the viscoelastic core are negligible. Furthermore, the constraining layer is assumed to be elastic and dissipates no energy, whereas the core is assumed to be linearly viscoelastic. In addition, the base structure is subjected to an axial ...