Representative volume element size of a polycrystalline aggregate with embedded short crack

A random polycrystalline aggregate model is proposed for evaluation of a representative volume element size (RVE) of a 316L stainless steel with embedded surface crack. RVE size is important since it defines the size of specimen where the influence of local microstructural features averages out, resulting in the same macroscopic response for geometrically similar specimen. On the other hand macroscopic responses of specimen with size smaller than RVE will, due to the microstructural features, differ significantly. Different sizes and orientations of grains, inclusions, voids,... etc are examples of such microstructural features. If a specimen size is above RVE size, classical continuum mechanics can be applied. On the other hand, advanced material models should be used for specimen with size below RVE. This paper proposes one such model, where random size, shape and orientation of grains are explicitly modeled. Crystal plasticity constitutive model is used to account for slip in the grains. RVE size is estimated by calculating the crack tip opening displacements of aggregates with different grain numbers. Progressively larger number of grains are included in the aggregates until the crack tip displacements for two consecutive aggregates of increasing size differ less than 1 %. At this point the model has reached RVE size. (author)