Switching of deformation modes in soft mechanical metamaterials

Mechanical metamaterials have attracted tremendous interests, owing to their fruitfulness of underlying physics and mechanics as well as diverse potential applications. Conventional soft mechanical metamaterials contain periodic distribution of holes having identical sizes, which can only display one mechanical function. Periodically dispersing a regular pattern of through-holes with two sizes into an elastomer results in metamaterials with more mechanical functions and deformation scenarios. We numerically investigate the deformation behaviors of this type of metamaterials. Switching of modes from the buckling-dominated deformation to a loss-of-instability deformation is emphasized. Replacing the pattern of holes with the same sizes by a pattern of holes with two sizes imposes higher compliance and even loss of negative Poisson’s ratio of the material.

机械超材料（Mechanical metamaterials）因其内在蕴含丰富的物理与力学机理，且具备多元化的潜在应用场景，故而受到了广泛关注。传统软质机械超材料通常采用尺寸均一的周期性孔洞排布，仅能实现单一的力学功能。在弹性体中周期性排布两种尺寸的规则通孔阵列，可制备出具备更多力学功能与变形模式的超材料。本研究通过数值模拟方法，对该类超材料的变形行为展开了系统探究，重点关注了变形模式从屈曲主导型变形向失稳主导型变形的切换过程。相较于原有的同尺寸孔洞排布，将其替换为双尺寸孔洞排布后，材料的柔度会显著提升，甚至会丧失负泊松比特性。