Significance of the characteristic length for mechanical modelling of ductile fracture

The ductile fracture behavior of materials is considerably influenced by the characteristic microstructural length which may be related to the average inclusion spacing. However, it is not easy to introduce this critical parameter into micromechanical modelling. An additional problem met at the simulation with micromechanical models is the sensibility of numerical results to the mesh size. In this work the nonlocal damage concept developed by Bazant was introduced into the modified Gurson model. The ability of the nonlocal micromechanical concept to reduce the mesh-size dependency and the relationship between the localization limiter and the characteristic length have been studied by simulating damage development in shear bands, necking regions and at crack tips.