In the fields of aerospace, flexible electronics, intelligent manufacturing, and MEMS, the mechanical metamaterials with remarkable zero thermal expansion of coefficient (CTE) are of increasing interest due to their advantages in maintaining their original shapes upon a temperature change. Though recently published researches have demonstrated several designs in achieving a desirable CTE, it is still very challenging to develop the mechanical metamaterial with high-level thermal–mechanical stability (i.e., CTE < 0.5 ppm/°C). Additionally, most of these studies only focused on obtaining a remarkable zero CTE through optimizing the geometrical parameters, and did not provide enough performances in consideration of their mechanical behaviors (e.g., lightweight, high specific modulus), imposing certain limitations on their operation in devices that require combined thermal–mechanical attributes. This paper demonstrates a mechanical metamaterial design concept with lightweight, high specific modulus properties and high-level thermal–mechanical stability. Each of the unit cell in our designs composed of two or four bilayer beams filled by hourglass lattices in Al and Ti materials offers a tunable CTE from negative to positive, revealing its capability to offer remarkable zero CTE. A theoretical model that preciously predicts the design’s thermal and mechanical performances provides a clear understanding of the effects of geometric parameters on their corresponding effective properties, facilitating the design of metamaterials with desired mechanical and thermal expansion performances. Excellent agreements between theoretical predictions, FEAs, and experiments demonstrate the advantages of our design in achieving the combined attributes of lightweight (i.e., relative density ${\overline{\rho }}_{Uniaxial}$ < 0.123 for the design with uniaxial thermal–mechanical stability and ${\overline{\rho }}_{Biaxial}$ < 0.069 for the one with biaxial thermal–mechanical stability), high specific modulus (i.e., 1104 kN$\cdot$ mm/kg and 1203 kN$\cdot$ mm/kg for the designs with uniaxial and biaxial thermal–mechanical stability), and a remarkable zero CTE ($\left|{\alpha }_{effective}\right|$ < 0.32 ppm/°C). Ashby plot of the effective CTE with respect to density, serving as an especially useful tool in selecting materials according to the requirements of practical applications, provides quantitative evidences for our design’s outstanding thermal–mechanical performances as compared to the previously reported studies.

在航空航天、柔性电子、智能制造和 MEMS 等领域，具有显着零热膨胀系数 (CTE) 的机械超材料因其在温度变化时保持其原始形状的优势而受到越来越多的关注。尽管最近发表的研究已经证明了实现理想 CTE 的几种设计，但开发具有高水平热机械稳定性（即 CTE < 0.5 ppm/°C）的机械超材料仍然非常具有挑战性。此外，这些研究大多只专注于通过优化几何参数来获得显着的零 CTE，并没有考虑到它们的力学行为（例如轻质、高比模量）而提供足够的性能，对它们在需要组合热机械属性的设备中的操作施加某些限制。本文展示了一种具有轻质、高比模量特性和高水平热机械稳定性的机械超材料设计概念。我们设计中的每个晶胞由两个或四个双层梁组成，由 Al 和 Ti 材料的沙漏晶格填充，提供从负到正的可调热膨胀系数，显示其提供显着的零热膨胀系数的能力。一个能够准确预测设计的热和机械性能的理论模型可以清楚地了解几何参数对其相应有效性能的影响，从而促进具有所需机械和热膨胀性能的超材料的设计。${\overline{\rho }}_{你n\mathrm{一世}\mathrm{一种}X\mathrm{一世}\mathrm{一种}升}$ < 0.123 对于具有单轴热机械稳定性和 ${\overline{\rho }}_{乙\mathrm{一世}\mathrm{一种}X\mathrm{一世}\mathrm{一种}升}$ < 0.069 对于双轴热机械稳定性），高比模量（即 1104 kN$\cdot$ mm/kg 和 1203 kN$\cdot$ mm/kg 用于具有单轴和双轴热机械稳定性的设计），以及显着的零 CTE（$\left|{\alpha }_{\mathrm{电子}FF\mathrm{电子}C吨\mathrm{一世}v\mathrm{电子}}\right|$< 0.32 ppm/°C)。与密度相关的有效 CTE 的阿什比图，作为根据实际应用的要求选择材料的特别有用的工具，与先前报道的研究相比，为我们设计的出色热机械性能提供了定量证据。