Application of Damage Concepts to Predict Creep-Fatigue Failures

The damage concept has been developed in terms of strain range in order to give a unified approach to high temperature failure. Interactive tests have been carried out on OFHC copper at 540°C and Sanicro 31 (Alloy 800) at 600°C. For the former, combined strain controlled low frequency and high frequency tests were undertaken whereas the latter metal was subjected to sequential tests involving monotonic creep and high frequency cycling. The damage concept based on non-linear accumulation predicted lives which were in agreement with those observed experimentally for the two materials.