Rib-reinforced ultralight and ultra-strong shell lattices

Abstract

Shell lattices are promising candidates for lightweight multifunctional applications for their geometric uniqueness and distinct mechanical properties. However, due to the transition from yielding-to-buckling failure mode, shell lattices exhibit notably reduced strength at low relative densities (RDs), making the design and optimization of ultralight and ultra-strong shell lattices challenging. Herein, a novel design of rib-reinforced shell lattices, namely ribbed shell lattices, is proposed to enhance the strength of ultralight triply periodic minimal surface (TPMS) shell lattices. By revealing the intrinsic relations between the curvature and stress directions of TPMS thin shell lattices, two groups of ribs are orchestrated along the representative curvature directions: the line of asymptotes (LOA) and the line of principal curvatures (LOC). Through physical realization and numerical simulations, incorporating ribs along the LOAs and LOCs that pass through the shell umbilical points is shown to enhance the strength by 112.3%, with an RD around 1.28%. Incorporating ribs can redistribute the stress and selectively strengthen thin shells to suppress their buckling deformation, especially at the umbilical region. The continuous ribs also provide additional load paths, resulting in improved load-bearing efficiency. These findings provide a practical design method for rib-reinforced ultralight and ultra-strong shell lattices against micro-architecture buckling failure.