Prediction and experimental verification of damping in 3-D braided textilestructural composites

The material damping characteristics of 3-D braided textile structural comp osites were investigated in this paper. A model for predicting damping in t hese materials was developed based upon the classical laminated plate theor y. The model modified the existing models for predicting the static moduli of 3-D textile structural composites by using the elastic-viscoelastic corr espondence principle. The basic engineering constants were replaced with th eir corresponding complex forms by applying the elastic-viscoelastic corres pondence principle to them. In this study, the basic damping loss factors ( i.e. eta(L), eta(T), eta(LT) and eta(upsilon LT)) were obtained by a modifi ed Hashin's theory, Rule-of-Mixture Laws, and an indirect method on the bas is of empirical works. From complex numerical results, we concluded that ax ial damping, flexural damping, coupling damping, and in-plane shear damping coefficients were all functions of the yarn orientation angle and fiber vo lume fraction in 3-D braided textile structural composites. Experimental da ta supported theoretically predicted results.