Lifetime prediction and constitutive modelling for creep fatigue interaction

The phenomena of creep, fatigue, and creep-fatigue interaction in metallic materials are examined with a focus on the underlying physical processes. Various lifetime prediction methods for creep-fatigue interaction are critically assessed, particularly through the lens of damage mechanics. The need for effective constitutive modeling of high-temperature mechanical behavior alongside lifetime prediction is emphasized, with principles and concepts clearly explained. Special attention is given to a relatively underutilized lifetime prediction rule for creep-fatigue interaction, developed at the University of Leoben in Austria, which is based on the principle of linear accumulation of strain rate modified creep damage (the SRM rule). This approach demonstrates that utilizing this rule, in conjunction with a suitable viscoplasticity model, significantly decreases the experimental data required for accurate lifetime predictions. The method proves to be practical and reliable for most cases of variable loading. This resource is particularly beneficial for students and engineers, as it offers a comprehensive analysis of the fundamental principles and assumptions of mathematical modeling in relation to the metallurgical aspects of deformation, damage evolution, and failure.