A strain energy density method for the prediction of creep-fatigue damage in high temperature components

摘要

The accumulation of creep-fatigue damage over time is the principal damage mechanism which will eventually lead to crack initiation in critical high temperature equipment. A model has been developed that assumes on a macroscopic level that the energy dissipated in the material may be taken as a measure of the creep damage induced in the material and hence the creep damage is directly proportional to absorbed internal energy density. The model developed is derived from considerations of mechanistic cavity growth and is based on rupture elongation to failure data using true strain. The predictions of the energy density exhaustion approach are compared with the results of creep-fatigue tests on low alloy ferritic steels. The predicted results of the energy density model are found to have good correlation with the measured creep-fatigue lives.