CHARACTERIZATION OF STRAIN-INDUCED DAMAGE IN COMPOSITES BASED ON THE DISSIPATED ENERGY DENSITY .1. BASIC SCHEME AND FORMULATION

An approach to characterizing failure behavior and degree of load indu ced internal damage in composite materials and structures is formulate d in Part I of this work. It is based on a systematic experimental pro cedure to observe the response of composite materials subjected to mul tiaxial load environment. The energy dissipated by internal failure me chanisms is employed as a measure of internal damage and is characteri zed by an energy dissipation function, which is identified by means of a deconvolution procedure using data provided by NRL's automated in-p lane loader testing machine. Part II of this work will display the dis sipated energy density distributions in composite specimens that are u sed for the in-plane loader machine and naval structures, while Part I II presents a general theory that includes the derivation for the cons titutive behavior of the damaged composites.