The linkage between microscopic cavitation damage and macroscopic crack growth

This paper is concerned with a recent microstructural approach to model cre ep crack growth. The model spans three different length scales, from the sc ale of individual cavities, through the grain scale up to the macroscopic s cale of cracks in components and test specimens. In order to study the init ial stages of creep crack growth, we consider a near-tip process window in which a large number of grains are represented discretely. This window is s urround by a standard continuum. Macroscopic specimen dimensions and loadin g configuration are communicated to this near-tip region by applying bounda ry conditions in accordance with the asymptotic stress fields for power-law creeping materials. The paper presents some novel results of this type of modeling obtained using remote higher-order crack-tip fields. Specific atte ntion is focused on the effect of random nucleation and grain deformation o n nonsymmetric crack growth from either initially sharp or blunt cracks. [S 0094-4289(00)00703-9].