Absorbing capabilities of additively manufactured lattice structure specimens for crash applications: Damage tolerant design and simulations

In the present work, the influence of defects on the compressive response of octet-truss AlSi10Mg lattice structure specimens produced with a selective laser melting process is investigated. The defect population in one cell, in two cells, and cubic specimens composed of 27 cells has been assessed with micro-computed tomography (micro-CT) analyses. The statistical distributions of the characteristic defect sizes, i.e., the equivalent diameter, the volume, and the surface, assessed in the lattice structure specimens and in volumes randomly extracted from a rectangular bar have been compared. Finally, the compressive behavior of lattice structure specimens has been simulated with a simplified damage-tolerant finite element model accounting for the influence of defects and compared with experimental results. The analyses have proven that the defect population in volumes extracted from a rectangular bar can provide reliable simulated results, even if micro-CT inspections of a unit cell or specimens made of several cells are suggested. Manufacturing defects strongly influence the structural integrity of lattice structures. Defect volume, surface, and equivalent diameter are reliable characteristic defect sizes. The defect population should be assessed on multiple cells for damage-tolerant design. Finite element analyses should model the influence of defect size.