Mechanical analysis and modeling of metallic lattice sandwich additively fabricated by selective laser melting

In order to balance the strength and weight, 3D lightweight metallic kagome lattice sandwiches were fabricated by selective laser melting with 304 stainless steel (SS) and Co-Cr-Mo (CCM) alloy. Systematical experiments, numerical modeling and theoretical prediction for compression and bending behaviors were conducted. The experimentally measured strengths are very close to the theoretical predictions, demonstrating the excellent mechanical properties. The numerical modeling can capture the stress-strain, load-deflection curves, and the failure mode is the strut buckling initiated from the plastic hinges with high stress level. The CCM alloy kagome lattice sandwich presents non-synchronous deformation. The buckling of the struts near bottom facesheets always arises first, and is followed by the subsequent buckling of the struts near up facesheets. The strength and modulus of CCM alloy are higher than those of 304 SS, resulting in relative high values of strength and load capacity for CCM alloy kagome lattice sandwich. In contrast, the superior plasticity of 304 SS enables relative high plastic deformation ability of 304 SS kagome lattice sandwich. The kagome lattice sandwiches provide a solution to effectively balance the strength and weight, as they present lower density than engineering alloys and higher strength than honeycombs, foams and pyramid lattice sandwich.