| Investigations of cyclic creep fracture are reviewed, from both microscopic mechanisms of creep deformation and creep damage and from macroscopic response of materials under a specified stress and temperature history. Various models and methods describing macroscopic cyclic creep response and various influencing factors are catalogued.;A continuum damage mechanics based constitutive model for describing cyclic creep response of commonly used engineering materials is proposed. The model can take into account the load cycling effect, the load dwell time effect and the interaction between creep damage and high temperature low cycle fatigue damage in cyclic creep fracture analysis. The model is incorporated into an existing finite element program for numerical analyses. Mixed implicit-explicit algorithm is adopted for integrating the rate form equations. The strain localization analysis is employed for simulating crack extension. Finite element equations incorporating the new model and the strain localization analysis are derived based on variational principles.;The effect of loading history on creep response and crack behavior, i.e., the incubation time for a crack to propagate and the subsequent crack growth rate, is studied systematically. Effects of the various influencing factors for cyclic creep fracture, such as load cycling effect, load dwell time effect and interaction between creep damage and high temperature low cycle fatigue damage, etc., are evaluated respectively. |
