CONVERGENT DEBONDING OF FILMS AND FIBERS

Debonding of films attached to substrates as well as fibers embedded i n matrices typically involves initiation, steady-state propagation and a final transient as the debond converges on an edge or another debon d. The emphasis in this paper is on the mechanics of the transient. Un der most circumstances, a converging debond crack is characterized by an energy release rate that approaches zero, causing the crack to arre st without attaining full debonding. The relevance of this phenomenon will be discussed with reference to the measurement of toughness for t hin film interfaces and the overall stress-strain behavior of ceramic matrix composites. (C) 1997 Acta Metallurgica Inc.