Deformation behavior of heterogeneous multi-morphology lattice core hybrid structures

Abstract

Additive manufacturing has greatly relieved the design freedom of lattice structures, including the geometric topological configurations and arrangement patterns of unit cells. Herein, the effects of spatial hybrid arrangement patterns on the compression performances of multi-layer lattice structures were investigated in terms of load-bearing capacity and deformation mode. Using four types of lattice unit cells with evident discrepancies in geometric morphologies and mechanical properties, three hybrid arrangements (horizontal, vertical, and circular) composed of any two types of cells were constructed according to natural biology. Several typical lattice core sandwich panels were fabricated by selective laser melting (SLM). The ultimate strengths and compressive moduli were assessed by experiments and finite element analysis. The data were then compared to theoretical simulations predicted by the traditional mixture rule. The results revealed significant effects of spatial arrangement patterns and cell performance differences on the overall mechanical performances, especially in terms of ultimate strength. The traditional mixture rule was found unsuitable for the prediction of hybrid lattice core panels strengths owing to discrepancies in node constrain degree and layer deformation distribution. Layer-by-layer failure behavior was identified as the main mode for the horizontal hybrid panels, whereas shear failure behavior played a dominant mode. Under identical relative density and arrangement patterns, panels contracted with horizontal hybrids were weaker than vertical ones. In sum, these findings look promising for future design of multi-scale lattice structures.