Bridged and cohesive crack models for fracture in composite material systems

The presentation reviews two modelling approaches used to study fracture in composite systems where nonlinear mechanisms arise along extended regions of the crack surfaces leading to so called large scale bridging conditions, the bridged- and the cohesive-crack models. Characteristic length scales and dimensionless groups that control fracture characteristics, size-scale transitions in the structural response of finite size members and modes of failure will be recalled and discussed. Applications to composite materials for civil, naval and aeronautical structures will be presented that highlight the significance of the bridged-crack approach in designing and optimizing new advanced composites with improved mechanical properties. Recent results on the problem of multiple dynamic delamination fracture in multilayered plates will be discussed with focus on the problem of energy absorption through multiple delamination.