Fracture modelling of 3D-Printed lattice structures via AA-FEM

Lattice structures are increasingly adopted as engineered materials for energy absorption applications due to their lightweight nature and geometry-driven mechanical response. However, their structural performance is strongly influenced by the interplay between material behaviour, lattice topology, and the resulting deformation and failure mechanisms, which often involve strain localization and crack propagation [1]. This phenomenon can be addressed through a continuous-discontinuous computational framework, where established techniques such as the Extended Finite Element Method (X-FEM) [2] or the Virtual Element Method (VEM) [3] are commonly adopted. In this work, a computational framework based on the Advanced Augmented-Finite Element Method (AA-FEM) [4] is employed to investigate fracture processes in periodic lattice structures. The approach introduces embedded discontinuities through interphase elements (IPH), enabling the simulation of crack initiation and propagation without remeshing, while naturally capturing the transition from diffuse damage to localized fracture. Material degradation is described through an isotropic damage model, allowing the identification of localization patterns governing structural collapse. Particular attention is devoted to the influence of lattice topology and geometric parameters on failure mechanisms and energy absorption performance. Numerical results are validated against experimental tests performed on 3D-printed polymeric lattice specimens manufactured via Fused Deposition Modeling (FDM). The comparison highlights the capability of the proposed framework to reproduce both global mechanical response and localized deformation patterns, including the emergence of dominant failure paths associated with different lattice configurations. The proposed approach provides insight into the relationship between geometry, damage evolution, and macroscopic response, supporting the design and optimization of lattice structures with enhanced energy absorption capabilities.