Programmable cell unit arrangement of 3D printing mechanical metamaterial undergoing tailorable local instability

3D printing mechanical metamaterial is one of the most popular research topics due to the advantages of rapidity, design, and programmable mechanical properties. Many previous studies had conducted on the 3D printing mechanical metamaterial using the holey column structure, however, there is few of reports on the effect of programmable cell unit arrangement on the mechanical metamaterials, of which the structural optimizations and designable strategies have not been understood yet. In this study, three types of holey column structures with a variety of rotation angles were designed and 3D printing manufactured. Effects of rotation angles of holes and their arrangements on mechanical properties and buckling modes were investigated using finite element analysis (FEA) simulations and experimental verifications for the 3D printing metamaterials. The compression-buckling behaviors can be tailorable by means of arrangement of the unit cells, i.e., auxeticity. Furthermore, a 3D printing mechanical metamaterial, which is made from the shape memory polymer (SMP), was fabricated to endow it with shape memory effect (SME) and designable mechanical behavior.