Computational Methods for Ductile Fracture Modeling at the Microscale

摘要

This paper is a state-of-the-art review of computational damage and fracture mechanics methods applied to model ductile fracture at the microscale. An emphasis is made on robust and stable methods that can handle heterogeneous structures, large deformations, and cracks initiation and coalescence. Ductile materials' microstructures feature brittle and ductile components whose heterogeneous behavior can give raise to cracks initiation due to stress concentration. Due to large deformations, cracks initiated by brittle components failure transform into large voids. These major voids interact and coalesce by plastic localization within ductile components and lead to final failure. This process can involve minor voids nucleated directly within ductile components at sub-micron scales. State-of-the-art discontinuous approaches can be applied to discretize accurately brittle components and model their failure, given that large deformations can be handled. For ductile components, continuous approaches are discussed in this review as they can model the homogenized influence of minor voids, hence alleviating the burden and computational cost overhead that an explicit discretization of those voids would require. Close to final failure, when major voids are coalescing, and the influence of minor voids becomes comparable to that of major voids, the transition from a continuous damage process within ductile components to the initiation and propagation of discontinuous cracks within these components has to be modeled. This review ends with a discussion on computational methods that have successfully been applied to model the continuous-discontinuous transition, and that could be coupled to discontinuous approaches in order to model ductile fracture at the microscale in its full three-dimensional complexity.