Investigation on Low-velocity Impact Response and Energy Absorption of Enhanced X-shaped Lattice Mechanical Metamaterials
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摘要: 点阵力学超材料具有轻质、可设计和抗冲击方面的优点,在航空航天等许多领域得到了广泛的应用。本文设计了一种米字型点阵力学超材料,采用选择性激光熔化技术制备了米字型点阵力学超材料试样,开展了落锤冲击试验和有限元数值模拟,研究了低速冲击载荷作用下点阵力学超材料的动态压溃行为和能量吸收机理,分析了冲击速度对米字型点阵力学超材料变形模式和能量吸收特性的影响规律。研究结果表明:冲击速度对米字型点阵力学超材料的变形模式有较大影响,在较低冲击速度下点阵力学超材料的变形模式与准静态压缩下的变形模式相似,均以剪切带周围胞元的逐层压溃为主;在较高冲击速度下点阵力学超材料的变形模式由“X”型剪切带转换为“V”型剪切带,最后演变为弧形剪切带;进一步研究发现,米字型点阵力学超材料呈现出一定程度的速率敏感性,随着冲击速度的增大,初始峰值应力、平台应力和比吸能增加。
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关键词:
Abstract: Lattice mechanics metamaterials have been widely used in various fields due to the lightweight, flexible designability and excellent impact resistance. In this paper, the enhanced X-shaped lattice mechanical metamaterials were designed and prepared by selective laser melting. The dynamic crushing behavior and energy absorption mechanism of lattice mechanics metamaterials subjected to low-velocity impact were carried out experimentally and numerically. The influence of impact velocity on the deformation mode and energy absorption capability of the enhanced X-shaped lattice mechanical metamaterials was analyzed. It is shown that the impact velocity has significant effects on the deformation mode of the mechanical metamaterials. The active deformation mode of X-shape lattice mechanical metamaterials subjected to lower impact velocity and quasi-static compression is collapse layer by layer. At higher impact velocities, the deformation modes of lattice mechanical metamaterials evolve sequentially from "X"-shaped to "V"-shaped and finally to arc-shaped shear bands. The enhanced X-shaped lattice mechanical metamaterials exhibit rate sensitivity. The initial peak stress, plateau stress and specific energy absorption increase with an increase in the impact velocity.-
Key words:
- mechanical metamaterial /
- low-velocity impact /
- dynamic response /
- deformation mode /
- energy absorption
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