A review of a time-dependent fracture life law (or model) based on a proposed multi-scale analysis

To solve the problem of structural safety under time-dependent fracture conditions, an algorithm of multi-scale hybrid mechanics from the nano-scale to the macro-scales is described. The paper presents an algorithm that links the physics of materials with life prediction determined by creep crack growth and addresses practical application which enables "prediction of fracture" to be developed from "the science of clarification of fracture mechanism" on the basis of the algorithm. In particular, in order to predict the fracture life of real components, the importance of the link between void mechanics caused by vacancy diffusion (micro mechanical factor), the stress tri-axiality, TF (a structural mechanical factor), and the material structure (a meso-mechanical factor) is shown in the proposed formulation for the activation energy of the thermally activated process of creep crack growth. A detailed discussion on these issues as well as on the algorithm relevant to the establishment of the law of creep crack growth life based on the multi-scale analysis is included ranging from the scale of micro damage to structural brittleness.