Multi-axial failure of metallic strut-lattice materials composed of short and slender struts

Results of a parametric investigation on the failure of metallic strut lattices subjected to multi-axial loads are presented. The study involves two microscopic parameters related to the geometry of struts: strut-level strengthening and slenderness ratios. The strengthening procedure is designed such that minimum-strengthening represents the octetruss while maximum-strengthening represents the three-dimensional Warren truss. This way, the effects of both strut-level stretching and bending on the deformation responses together with coupled failure due to plastic yield and elastic buckling can be studied. The evaluated theoretical failure envelopes that include microscopic global and localized failure compare well with the numerical failure data obtained from finite element analysis. Among results, while the strengthening and slenderness ratios expectedly influence the sizes and shapes of the failure surfaces, they also dramatically alter microscopic deformation mechanisms leading to macroscopic failure.