Multiscale modelling of fracture

Defects like cracks and dislocations evolve at nano scales and influence the macroscopic properties such as strength,toughness and ductility of a material. Molecular dynamics simulations promise to reveal the fundamental mechanics of material failure. The computational expense of molecular dynamics simulations limits its application to engineering problems involving macroscopic cracks and shear bands, which occur at larger length and time scales. Therefore, multiscale methods have been developed bridging different time and length scales. However, the existing multiscale methods for fracture do not adaptively adjust the fine scale domain as the crack propagates. Most methods, therefore only “enlarge” the fine scale domain and therefore drastically increase computational cost. Adaptive adjustment requires the fine scale domain to be refined and coarsened. One of the major difficulties in multiscale methods for fracture is to up-scale fracture related material information from the fine scale to the coarse scale, in particular for complex crack problems. The present talk is on the developed multiscale methods and their applications to fracture.