Vibration and Damping of Composite Structures

AbstractToday the composite materials are more and more used to provide structure for several industrial applications. The aeronautic industry is coming the last in this material user community, but recently the use in aeronautic is increasing, in fact if in the past the composite (mainly, carbon fiber based) have been used for non critical structure components, like small doors or firings, today the use has been applied to wing and tail components, recently the use has been enlarged to the main fuselage structure. One of the important design requirements of this new structure is to comply with the very demanding constraints related to the vibration and correlated sound generation.There are many applications in which the vibration response of structures is important. These include, among others, noise and vibration control techniques applied to different structures: small, as an example, a tennis rackets or very large as an aircraft. In these examples, the dynamic properties of structures can contribute to excessive vibration, which produces high noise levels, fatigue failure, premature wear, operator discomfort, and unsafe operating conditions. Laminated composites can be effective in eliminating vibration and sound. This is a recent technological development, and this article provides an introduction and hopefully stirs the interest of engineers and other product development people. The process by which a polymer converts vibration energy to heat is known asdamping. The process by which a polymer, or anything else, is moistened by water is known asdampening. This article deals with the first of these terms.After reviewing the basic concepts and definitions of vibration, this article discusses methods of vibration analysis, which include macromechanical and micromechanical modeling. This is followed by an introduction to the experimental determination of composite vibration response. The effects of material variables and structural parameters on the composite vibration are discussed in a subsequent section. Finally, a section is devoted to a review of the application of vibration techniques and concepts to noise control, composite design, and nondestructive evaluation (NDE).