A robust life prediction model for a range of materials under creep-fatigue interaction loading conditions

This paper develops a robust creep-fatigue interaction (CFI) life prediction model which is superior to the existing methods. Specifically, the newly proposed creep damage incorporates the effect of creep strain, which introduces the critical creep strain energy density rate and creep strain evolution term. The predictions are carried out for various materials, including martensitic heat-resistant steel, austenitic stainless steel, nickel-based superalloy, and different loading conditions, including conventional CFI and hybrid-controlled CFI loadings. The results show that all of the tested data falls within ± 2.5 error band, demonstrating the broad applicability of the proposed model. Based on the proposed model, a continuous CFI failure envelope independent of material, temperature, and CFI loading type is proposed, with almost all the data points lying outside the envelope.