Damage Percolation Modeling of Void Nucleation in Aluminum Alloy Sheet

Damage-induced ductile fracture is a strongly heterogeneous process where micro-voids nucleate, grow and coalesce within particle clusters. To capture the localized nature of ductile fracture, a damage percolation model has been developed to predict damage development in the actual particle distribution obtained from tessellated particle fields. Percolation modeling allows for the characterization of void nucleation and coalescence under various loading conditions within a heterogeneous particle distribution. Particularly, void nucleation can be characterized under different stress states for individual particles. The objective of the present work is to apply the percolation model to a damage-sensitive aluminum alloy, AA5182, to develop a nucleation criterion as a function of stress state and particle morphology. The nucleation model is calibrated by subjecting three particle fields to different levels of uniaxial and biaxial stretching in order to achieve fracture predictions in agreement with an experimental forming limit curve.