EXTENSION OF A CRACK GROWTH MODEL WITH FATIGUE-CREEP-ENVIRONMENT INTERACTION TO NON ISOTHERMAL LOADING

摘要

This paper deals with the extension of a crack growth model to high temperature, complex loading with application to a turbine disc. The proposed model is based on an extensive experimental study performed by SNECMA on superalloy N18 from 450℃ to 650℃, in isothermal and also in non isothermal condition, which comprises fatigue with or without hold times and special sequence tests representative of the disc in service. The crack growth model is built up on the framework of classical linear elastic fracture mechanics. Time effects at high temperature are expressed by creep-fatigue and oxidation-fatigue interactions. The proposed work for non-isothermal condition is attractive for easy model identification on a large temperature domain. Model predictions are shown for a set of experimental data including complex loading in non-isothermal condition.