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中文核心期刊

多层级曲梁多稳态超材料的可重用性研究

RESEARCH ON REUSABLE PROPERTIES OF MULTISTABLE METAMATERIAL OF HIERARCHICAL CURVED BEAMS

  • 摘要: 多稳态超材料凭借其出色的力学性能而广受关注和应用. 然而, 现有研究主要集中在单曲梁结构, 对于由多层级曲梁单胞构建的复杂拓扑结构的可重复吸能特性缺乏深入探讨. 此外, 与传统材料相比, 多稳态超材料在循环加载下的疲劳性能也鲜有研究. 文章以两端固支直梁一阶屈曲模态为初始构型构造曲梁单胞, 并通过3D打印技术制备双材料双稳态单元. 进而建立多层级曲梁结构, 并给出预测多层级曲梁正则化的力和势能随位移变化的5次、6次多项式经验公式, 相比于以往3次、4次多项式结果更为准确. 以双曲梁单胞为基本单元, 通过中心旋转的方式设计三维点状多稳态超材料, 研究其稳态性能和力学特性. 并通过参数化分析研究单元几何参数和模块化拓扑构型对结构力学响应的影响, 最后通过疲劳实验验证了该类多稳态超材料的疲劳寿命. 该结构能够在小变形和大变形范围内实现正负刚度的转变, 同时变形是弹性稳定的, 即杨氏模量基本保持不变, 且具有多稳态和可重复吸能特性. 随着双曲梁几何参数Q (高厚比)的增大, 其有效压溃距离和能量吸收效率随之增加. 提出的设计策略为制造多稳态多步可逆变形的力学超材料开辟了新路径, 并为设计材料-结构-功能一体化的工程材料提供了一种新思路.

     

    Abstract: Multistable metamaterials have garnered widespread research and application due to their excellent mechanical properties. However, existing literature has primarily focused on single curved beam structures, while the study of the repeatable energy absorption characteristics of multistable metamaterials constructed from hierarchical curved beam unit cells remains limited. Furthermore, compared to conventional materials, the fatigue performance of multistable metamaterials under cyclic loading has been relatively unexplored. In this paper, a curved beam unit cell was constructed using the first-order buckling mode of a straight beam with fixed ends as the initial configuration. This unit cell was then employed to create a bi-material bistable unit through 3D printing technology. Subsequently, a hierarchical curved beam structure was established, and empirical formulas yielded more precies results compared to the previous third-order and fourth-order polynomial formulations. By employing the double-curved beam unit cell as the fundamental building block, a three-dimensional DOT multistable metamaterial was designed through center rotation, and its steady state performance and mechanical characteristics were thoroughly investigated. The structural mechanical response was investigated by conducting parametric analyses to examine the influence of unit geometric parameters and modular topology configuration. Finally, fatigue experiments were performed to demonstrate the reusability of this type of multistable metamaterial. The proposed structure enables the transition between positive and negative stiffness within the small and large deformation range. Moreover, the deformation exhibits elastic stability, indicating that the Young's modulus remains relatively constant. The structure also possesses multi-stable, programmable, and repeatable energy absorption characteristics. The effective crushing distance and energy absorption efficiency of the double curved beam increase with the geometric parameter Q. The design strategy presented in this study opens up new avenues for fabricating mechanical metamaterials capable of multi-step reversible deformation, thereby offering a novel approach for engineering materials design that integrates material properties, structural behavior, and functional attributes.

     

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