Phase-field modeling and validation of fracture toughness of octet-truss lattices

This study presents a physics-based phase-field fracture model to predict the fracture toughness of lattice materials. By correlating the length scale parameter with the physical properties of the base material, this model enables crack propagation prediction across complex geometries without recalibration. Experimental validation on additively manufactured AlSi10Mg specimens demonstrates that the model accurately captures the density-dependent fracture evolution. The results reveal a mechanism transition from topology-dominated crack deflection (±45°) at low relative densities to bulk-like straight cracking at high densities. In addition, parametric studies further confirm an approximately linear relationship between fracture toughness and relative density. The model achieves excellent agreement in toughness prediction compared to experiments, providing a validated foundation for damage-tolerant design of lightweight aerospace structures.