Investigating Mode I Fracture of Ti-6Al-4V Lattice Structure Fabricated by Laser Powder Bed Fusion

This study experimentally and numerically investigates the mode I fracture behavior of near-isotropic Face- and Simple-Center Cubic (FSCC) lattice structures fabricated from Ti-6Al-4V using Laser Powder Bed Fusion (PBF-LB/M). Single-edge notched bending (SENB) specimens were subjected to quasi-static three-point bending tests, and scanning electron microscopy (SEM) was conducted on the fracture surfaces to analyze crack propagation paths and crack planes within the struts. To efficiently predict damage initiation and evolution without the high computational cost of explicitly modeling complex lattice architectures, an equivalent solid material model (ESMM) was employed in conjunction with the eXtended Finite Element Method (XFEM). The maximum principal stress and fracture energy power-law criteria were utilized to simulate damage initiation and evolution in three-dimensional numerical simulations. By applying a common calibration factor to the base material properties, the integrated ESMM-XFEM approach demonstrated good agreement with the experimental load-displacement responses, exhibiting minimal differences of 2.2% and 7.9% for peak load and stiffness, respectively. These findings validate the consistent mode I fracture resistance of the PBF-LB/M-fabricated Ti-6Al-4V FSCC lattice, establishing the ESMM-XFEM framework as an efficient tool for evaluating damage-tolerant lattice components.