Damping of Materials and Structures

Abstract

Damping is a phenomenon that can be observed in connection with all kind of materials: solid, liquid, or gaseous. Any kind of time-dependent change in stresses or strains of the material results in a loss of mechanical energy, which in most cases is transformed into thermal energy. However, all the other mechanisms such as the conversion into electrical energy or any kind of radiation over the system’s boundaries play a role. Typical observations that can be made in connection with damping are the occurrence of creep and relaxation processes or hysteresis curves in the case of cyclic loadings. The overall damping is influenced by a variety of mechanisms, especially for structures assembled from different components. No matter whether the presence of damping is sought or should be avoided in technical applications, for any kind of tuning or optimization of a system under consideration, a basic understanding of the underlying physics is needed. This is especially true if calculations or simulations have to be run in order to predict the dynamical behavior of a system. This chapter intends to introduce the reader into the subject and provide an extensive overview on the different aspects of damping regarding the fundamentals, mathematical, and numerical models as well as experimental techniques for the detection of damping properties. It shall give an overview of the state of knowledge and experience gathered in various fields of application and research. For further information, the reader is referred to various publications and textbooks whenever needed. This chapter is organized as follows: Sect. 1 provides an extensive overview on the topic, the classification of damping phenomena, and some remarks on computer-based programs. Section 2 refers to the damping of solids, while Sect. 3 extends the view on structures assembled from different components. Section 4 deals with different mathematical models toward the description of damping and relevant numerical approaches. Experimental techniques for the detection of the damping parameters needed for calculations are described in Sect. 5. This includes possible instrumentation as well as analytical methods. Finally, in Sect. 6, an application of the whole subject covering the detection of damping properties, its mathematical representation, and parameter identification along with a numerical simulation is presented as an example. Conclusions from this chapter are drawn in Sect. 7.