Influence of Material Nonlinearity on the Effective Fracture Resistance of Porous Materials

ABSTRACT In this work, we investigate the simulation‐based determination of the effective fracture resistance of porous materials, taking into account non‐linear material behavior. Following the approach of Hossain et al., we conduct numerical experiments to identify effective crack resistance as a material parameter. Displacement boundary conditions corresponding to a steadily propagating macroscopic crack are applied to a representative microstructure. At the microscale, crack growth is simulated without prior assumptions regarding crack paths, continuity of propagation, or other features. The maximum value of the macroscopically acting J ‐integral defines the driving force required to advance the crack by a macroscopic length increment without arrest, which we refer to as the effective crack resistance. To simulate crack evolution in the microstructure without predefined growth assumptions, we employ a phase‐field model. In contrast to our previous work on the topic, we employ a Ramberg–Osgood‐like ansatz to consider non‐linear material behavior. We study the effect of the material law on the effective fracture toughness as defined in Hossain et al. Our findings indicate that a material law that allows more energy to be dissipated until fracture is a more reliable indicator of effective fracture toughness than high tensile strength in porous materials.