Mechanical metamaterials have gained increasing interest owing to its unique properties and promising applications. However, most developed mechanical metamaterials feature a single-step pathway and/or a single deformation mode, which limits their multi-task applications. In this paper, a multi-step metamaterial (MSM) is introduced. Under compression, the MSM can translate global loading into multiple pathways of deformation, giving rise to multi-stress plateaus in the stress-strain curves. The underlying mechanism is the combination of sequential snap-through and Euler buckling at microscopic unit cell level. Theoretical models are developed to quantify the multi-step deformation feature of the MSM and are validated by experiments and finite element simulations. By varying the geometric parameters of the constituent components of the MSM, its deformation can be programmed. The concept of the developed MSM provides a new perspective for designing metamaterials with multiple tasks, e.g., an energy absorber suitable for both light and heavy impacts, logic gates for manipulating mechanical signals in mechanical computing, among others.

机械超材料由于其独特的性能和有希望的应用而受到越来越多的关注。但是，大多数已开发的机械超材料都具有单步路径和/或单一变形模式的特征，这限制了它们的多任务应用。本文介绍了一种多步骤超材料（MSM）。在压缩下，MSM可以将整体载荷转换为多种变形途径，从而在应力-应变曲线中产生多应力平稳期。潜在的机制是在微观晶胞水平上依次咬合和欧拉屈曲的组合。建立了理论模型以量化MSM的多步变形特征，并通过实验和有限元模拟对其进行了验证。通过更改MSM组成部分的几何参数，它的变形可以编程。已开发的MSM的概念为设计具有多种任务的超材料提供了新的视角，例如，适用于轻度和重度撞击的吸能器，用于在机械计算中处理机械信号的逻辑门等。