Creep Rupture Due to Material Damage by Cavitation

Abstract

A phenomenological model to predict creep rupture times, based on material damage due to void growth and coalescence is presented. The model employs the Gurson-Tvergaard yield function together with the Norton-Baily power creep law. Rupture occurs at the end of a tertiary creep stage when the load-carrying capacity of the test-piece vanishes. Formulations for both uniaxial and triaxial conditions are given. Comparisons among the predictions of the present model and experiments for a vast number of data points indicate satisfactory agreement. A relation incorporating steady-state creep rate, rupture strain and rupture time is suggested. Furthermore acceptable correlation of the creep-rupture strength and creep strength to cause a specified creep strain is obtained.