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中文核心期刊

新型负刚度吸能结构力学特性分析

MECHANICAL PROPERTIES ANALYSIS OF A NEW ENERGY ABSORBING STRUCTURE WITH NEGATIVE STIFFNESS

  • 摘要: 负刚度结构作为一种具有广泛应用前景的力学超材料, 在吸能、减振及降噪等领域呈现出显著的优势, 但传统负刚度结构较低的比能吸收效率以及多稳态非自主回弹等特征, 严重限制了其工程应用. 为解决该问题, 通过单胞构型设计, 提出了一种新型可自主回弹的三维负刚度结构. 该结构利用串联的负刚度单胞在加载−卸载过程中, 曲梁胞元的自主反弹, 实现结构循环加载和多次重复利用; 通过凹槽深度设计抑制单胞多稳态的出现, 并且通过调整侧壁厚度, 控制曲梁屈曲模态的形式, 从而增大负刚度临界载荷差值, 实现吸能效率的显著提升. 随后为实现在复杂载荷环境下的高吸能, 对结构尺寸进行梯度设计, 提出了一种梯度负刚度结构, 利用有限元方法比较分析梯度负刚度结构与均匀负刚度结构在不同载荷作用下的吸能效果. 研究结果表明, 该梯度结构因微结构尺寸的不同, 具有不同的负刚度临界载荷最大值, 从而使其在不同的冲击载荷环境下, 在实现自主回弹的基础上, 均呈现出较好的吸能效率. 该新型负刚度结构为振动控制和结构重组等工程应用提供了技术支持.

     

    Abstract: As a kind of mechanical metamaterial with wide application prospect, negative stiffness structures show significant advantages in energy absorption, vibration attentuation, and noise reduction . However, their engineering applications are severely limited attributed to the low specific energy absorption efficiency and non-autonomous spring-back of negative stiffness structures with the speciality of multi-stability. In order to solve this problem, by means of cell configuration design, a new kind of three-dimensional negative stiffness structure with the characteristic of autonomous spring-back is proposed in this paper. For this negative stiffness cells in series, the self rebound of curved beams during the loading and unloading process is used to realize the cyclic loading and multiple reuse of the structure.The multi-stability is restrained by adding a groove of certain depth. The buckling mode is selected via the adjustment of side wall thickness. The difference between critical loads of negative stiffness is thus enlarged, accordingly, the energy absorption efficiency is significantly improved. Then in order to achieve high energy absorption under complex load environments, the gradient design of structure size is carried out, and a gradient negative stiffness structure is proposed. The energy absorption efficiency of gradient negative stiffness structure and uniform negative stiffness structure under different load cinditons is compared by finite element simulations. Analytical and numerical results reveal that for the newly developed negative stiffness structure, not only the feature of autonomous spring-back is achieved, but also the energy absorption ability is improved. Moreover, different critical load maximums for negative stiffness are obtained for the gradient structure due to different microstructure sizes, which makes it to exhibit better energy absorption efficiency on the basis of realizing autonomous spring-back under various impact load environments. The new energy-absorption structure proposed in this paper provides technical support for engineering applications such as vibration attenuation and structure reorganization.

     

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