Lifetime prediction and constitutive modelling for creep-fatique interaction

The phenomena of creep, fatigue and creep-fatigue interaction in metallic materials are reviewed and studied with respect to the underlying physical processes. Different approaches and methods of lifetime prediction for the regime of creep- fatigue interaction are critically reviewed, particularly from the point of view of damage mechanics. Because of the clear need for constitutive modelling of the mechanical behaviour of a material at high temperatures in conjunction with lifetime prediction, the principles and concepts of constitutive modelling are explained. Special emphasis is placed on one particular, as yet little used lifetime prediction rule for the creep-fatigue interaction regime (developed at the University of Leoben in Austria several years ago), based on the principle of linear accumulation of strain rate modified creep damage (the SRM rule). It is shown that the application of this rule supported by a suitable constitutive model of viscoplasticity substantially reduces the amount of experimental data required for lifetime prediction. This method of lifetime prediction in the creep-fatigue interaction regime is shown to be practicable and reliable for most general cases of variable loading. The book may be especially useful to those students and engineers who should get knowledge of two aspects of this topic as the book contains an analysis of the basic principles and assumptions of the mathematical modelling of the mechanical behaviour of a material and relates this to the metallurgical background of the processes of deformation, evolution of damage and failure.