Structural Dynamic Analysis with Generalized Damping Models: Identification

Chapter 3

Identification of Non-viscous Damping

Linear systems must generally be expected to exhibit non-viscous damping. In Chapter 2, it was shown that when a system is non-viscously damped, it is possible to fit a viscous damping model to the set of measured transfer functions but that the fitted damping matrix will be non-symmetrical. The fitted model may also be misleading in other ways: for example, it may predict the wrong spatial distribution of damping over the structure. Of course, a priori selection of viscous damping in the identification procedure rules out any possibility of recognizing other damping behavior present in the structure. In this chapter, we consider the identification of certain non-viscous damping models in the context of general multiple-degrees-of-freedom (MDOF) linear systems.

A key issue in identifying non-viscous damping is to decide on an appropriate damping model to consider. A brief review on available damping models may be found in section 1.1 of [ADH 14]. There have been detailed studies of material damping and of specific structural components. Excellent accounts of different mathematical methods for modeling damping in (solid) material and their engineering applications are given in [LAZ 68, BER 73, UNG 73]. The book by Nashif et al. [NAS 85] presents more recent studies in this area. Apart from material damping, a major source of energy dissipation in a vibrating structure is the structural joints. Here, energy loss can take place through ...