A new energy gradient-based model for LCF life prediction of turbine discs

Abstract

With continuous raising of thrust-weight ratio, low cycle fatigue (LCF) at high temperature is one of main failure modes for engine hot section components. Accurate life prediction of turbine discs has been critical for ensuring the engine integrity. According to this, a new LCF model through combining the energy gradient concept with critical distance theory is proposed for fatigue life prediction of turbine discs. In this paper, assuming that the processes of crack initiation and propagation in a LCF regime can be described by the cumulative strain energy. A relationship between the total strain energy in the fatigue process zone and the LCF life is explored. In particular, the energy parameters are weighted based on the energy gradient in the fatigue process zone. Using experimental data of GH4169 alloy at 650°C, a good agreement was achieved between model predictions and experimental results.