3D-printed bioinspired cage lattices with defect-tolerant mechanical properties

The imperfection of additive manufacturing process leads to the deviation of resulting 3D-printed structures from originally designed structures. Such geometric defects potentially compromise the mechanical properties of 3D-printed mechanical metamaterials with micro/nano-scale lattice structures. Understanding the effect of geometric defects on mechanical properties is essential for the design of those mechanical metamaterials. This study proposed a pair of bioinspired cage lattices with defect-tolerant mechanical properties, namely N₃₀S₆₀ and N₆₀S₁₂₀ cage lattices. The correlations between their designed structures, 3D-printed structure, geometric defects, and mechanical performances were investigated by in-situ mechanical testing, computed tomography scanning, and different numerical models. The 3D-printed structures exhibit superior specific stiffness (up to 550.85%) and specific energy absorption (up to 43.70%) than that of designed structures without structural defects. The geometric defects were classified into three categories, namely node offset defect, radius offset defect and axis offset defect. By analysing the individual effect of different kinds of defects, it is found that node offset defect may enhance mechanical properties attributed to the change in deformation mode. Our work illustrates the important influence of geometric defects on 3D-printed structures in additive manufacturing and shed lights into the design of 3D-printed structures incorporating the effect of geometric defect.