Hierarchical truss-core sandwich cylinder: Additive manufacturing, testing and multi-elastoplastic-failure analyzing

To develop lightweight aerospace structures, a hierarchical truss-core sandwich cylinder (HTSC) was designed, additively manufactured, tested and analyzed. The powder bed fusion (PBF) technique, a form of laser additive manufacturing (AM), was employed to print the HTSC. Uniaxial compression experiment reveals that the AM HTSC exhibits excellent mechanical performances with prolonged plastic deformation and ultimate failure of local plastic buckling. A multi-elasoplastic-failure theory was proposed to consistently predict the plastic buckling load with the experiment. Finite element modeling (FEM) was employed to examine the interplay between the local and global plastic post-buckling modes. Compared with corrugated-core and X-core sandwich cylinders, the HTSC has comparable mechanical performance when the diameter is 300 mm, while significantly outperforms the alternatives in terms of ultimate load and plastic deformation abilities when the diameter is enlarged to 3962.4 mm. At the same time, the long plastic platform deformation confirms that the failure of the AM HTSC might not present itself as a catastrophic sudden failure. These findings suggest that to make large-sized aerospace cylinders, this hierarchical truss-core sandwich configuration is a more suitable alternative design scheme.