AN OXIDATION - CREEP - FATIGUE DAMAGE MODEL FOR FATIGUE AT HIGH TEMPERATURE AND UNDER THERMAL TRANSIENTS

摘要

Damage modelling is considered for gas turbine components under cyclic loading at high temperature. Non linear accumulation of damage is made taking into account the synergy between oxidation, creep and fatigue. Damage is assumed to be the growth of a major microcrack which is described through a Basquin - type criterion in a microstructure element at the crack tip. Interaction with creep is made using Rabotnov equation and oxidation - embrittlement is taken into account using intergranular oxidation kinetics deduced from metallography. Predictions of the model are compared with low frequency low-cycle fatigue, thermal - mechanical fatigue and thermal shock results on a wrought superalloy.