Active and Passive Vibration Damping

8Advanced Damping Treatments

8.1 Introduction

This chapter presents a brief summary of the basic characteristics of some of the important advanced damping treatments with attractive characteristics that potentially can present effective means for enhancing the structural damping either passively or actively.

Distinct among the considered treatments are: the stand‐off damping treatment, functionally graded damping treatment, active piezoelectric damping composites (APDCs), passive magnetic composites (PMCs), and negative stiffness composites (NSCs). All five classes of damping treatments aim to provide novel and innovative means for improving the damping behavior over that of conventional constrained damping layer treatments.

In stand‐off damping treatments, discussed in Section 8.2, the enhancement is achieved passively by using a stand‐off layer (SOL) to move the viscoelastic layer away from the neutral axis of the base structure and thereby magnifying the shear strain and the energy dissipated by the viscoelastic matrix (VEM) (Whittier 1959).

The improvement in the damping characteristics by using the functionally graded damping treatment, in Section 8.3, takes place by optimally grading the shear modulus distribution over the length of the treatments. Optimal grading aims to place stiffer damping treatments in the high shear strain zones and softer damping treatment in the zones of low shear strain in order to maximize the total energy dissipation over the entire length ...