The Emergence of Sequential Buckling in Reconfigurable Hexagonal Networks Embedded into Soft Matrix

Abstract

The extreme and unconventional properties of mechanical metamaterials originate in their sophisticated internal architectures. Traditionally, the architecture of mechanical metamaterials is decided on in the design stage and cannot be altered after fabrication. However, the phenomenon of elastic instability, usually accompanied by a reconfiguration in periodic lattices, can be harnessed to alter their mechanical properties. Here, we study the behavior of mechanical metamaterials consisting of hexagonal networks embedded into a soft matrix. Using finite element analysis, we reveal that under specific conditions, such metamaterials can undergo sequential buckling at two different strain levels. While the first reconfiguration keeps the periodicity of the metamaterial intact, the secondary buckling is accompanied by the change in the global periodicity and formation of a new periodic unit cell. We reveal that the critical strains for the first and the second buckling depend on the metamaterial geometry and the ratio between elastic moduli. Moreover, we demonstrate that the buckling behavior can be further controlled by the placement of the rigid circular inclusions in the rotation centers of order 6. The observed sequential buckling in bulk metamaterials can provide additional routes to program their mechanical behavior and control the propagation of elastic waves.

Morphologies of Surface Perforations and Parallel Cylinders Coexisting in Terraced Films of Block Copolymer/Homopolymer Blends with Oxygen Plasma Etching

“…Other unbalanced stresses are also possible. It has been well demonstrated that buckling imposed on hexagonal networks can produce a global alternating pattern. , Similarly, our films should experience unbalanced stresses such as buckling during cooling. Note that the molecular weight of the hPS chains is much lower than that of the PS and PMMA blocks.…”

Compressive performance of 3D printed fault‐tolerant polymer lattice structures

“…When the strain increases to a certain threshold, the sacrificed unit fails, and the overall structure remains intact. The other is to prevent the propagation of cracks and the initiation of secondary cracks by setting rigid inclusions in the material 37,38 . In paper, 39 a hybrid lattice (bi‐lattice) structure composed of beam elements with different thicknesses was designed, composed of hexagonal and rhombohedral lattices.…”

“…The other is to prevent the propagation of cracks and the initiation of secondary cracks by setting rigid inclusions in the material. 37,38 In paper, 39 a hybrid lattice (bi-lattice) structure composed of beam elements with different thicknesses was designed, composed of hexagonal and rhombohedral lattices. The bi-lattice structure was analyzed by theoretical calculation and simulation.…”