Multi-failure analyses of additively manufactured lattice truss sandwich cylinders

Innovative sandwich cylinders with pyramidal lattice truss-cores were designed, printed, tested and analyzed. The selective laser melting (SLM) additive manufacturing (AM) technique was applied to ensure the quality of the structure, including the diameter of lattice struts, the thickness of inner and outer skins, and the joints between the skins and the lattice struts. Uniaxial compression tests of two groups of aluminum alloy sandwich cylinders were performed. The testing results showed that the cylinders failed at the facesheet yielding, which was followed by the post-plastic local buckling. A new multi-failure theory was proposed, which can consistently predict the plastic buckling load and provide a hierarchical failure map by covering all elastic and plastic buckling modes. The newly proposed multi-failure theory provides a method for the optimal design of additively manufactured lattice-core sandwich cylinders.