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中文核心期刊

新型节圆正弦蜂窝面内压缩力学性能研究

IN-PLANE COMPRESSION BEHAVIOR OF SINUSOIDAL HONEYCOMB WITH CIRCULAR NODES

  • 摘要: 面内压缩载荷下, 曲壁蜂窝可有效改善直壁蜂窝出现的应力集中问题. 为进一步提高曲壁蜂窝的抗冲击性能, 在已报道的正交正弦蜂窝(orthogonal sinusoidal honeycomb, OSH)的节点处插入薄壁圆环, 得到了一种新型节圆正弦蜂窝(sinusoidal honeycomb with circular nodes, CSH). 通过3D打印聚乳酸(PLA)制备了两种蜂窝试样进行准静态压缩实验, 并采用LS-DYNA进行有限元数值模拟, 实验结果和数值模拟结果有较好的一致性, 相比OSH, CSH因节圆的增加第2平台应力大大提高. 通过验证有效的数值模拟方法系统地研究了几何参数及冲击速度对CSH面内压缩力学性能的影响. 结果发现: CSH应力−应变曲线具有两个平台阶段, 基于蜂窝胞元不同阶段特有的变形机制, 推导出双平台应力的理论解, 其结果与数值模拟结果较为一致. CSH的第1平台应力几乎不受节圆半径的影响, 但随着振幅的减小及壁厚的增大而增大. 第2平台应力随振幅的减小、节圆半径和壁厚的增大而增大. 此外, CSH在第2平台阶段与密实阶段之间还增加了一个因节圆变形导致的应力增强阶段, 这极有利于提高CSH的吸能性能. 最终, CSH在密实应变前的总比吸能随振幅的减小、节圆半径和壁厚的增大而增大. 冲击速度从\text2 m/s提高到100\text m/s, CSH的负泊松比效应逐渐减弱, 但即使在100 m/s的高速冲击下, 仍有轻微的负泊松比效应. 所有速度下CSH的吸能性能均优于OSH, 且低速和中速时优势更为明显, 比吸能分别提高了1.84倍和0.75倍.

     

    Abstract: Curved wall honeycomb can effectively improve the problem of stress concentration in straight wall honeycomb under in-plane compression load. To further enhance the impact resistance of curved wall honeycomb, a novel sinusoidal honeycomb with circular nodes (CSH) was obtained by inserting thin-walled circular rings at the nodes of the orthogonal sinusoidal honeycomb (OSH) which has been reported. Two kinds of 3D printed polylactic acid (PLA) honeycomb specimens were prepared for quasi-static compression experiments, and these experiments were numerically simulated in LS-DYNA software. There is a good agreement between the experimental and numerical results. Compared to OSH, the second plateau stress of CSH is greatly increased due to the addition of the circular nodes. The effects of geometric parameters and impact velocity on the mechanical properties of CSH under in-plane compression were systematically studied by the validated numerical simulation methods. The results show the stress-strain curve of CSH at low velocity has two plateau stages. Based on the deformation mechanism of honeycomb cells at different stages, the theoretical solutions of the two plateau stress are derived, which are consistent with the numerical simulation results. The first plateau stress of CSH is hardly affected by the circular radius, but increases with the decrease of the amplitude and the increase of wall thickness. The second plateau stress increase with the decrease of the amplitude and the increase of circular radius and wall thickness. In addition, stress-strain curve of CSH has a stress enhancement stage caused by the flattening deformation of circular nodes between the second plateau stage and the densification stage, which is very beneficial to improve the energy absorption of CSH. The total specific energy absorption of CSH before the densification strain increases with the decrease of amplitude and the increase of circular radius and wall thickness. When the impact velocity increases from 2m/s to 100 m/s, the negative Poisson's ratio effect of CSH gradually weakens, but even when the velocity is as high as 100 m/s, CSH still has a slight negative Poisson's ratio effect. The energy absorption performance of CSH is better than that of OSH under the impact of various velocities, especially at low and medium velocities, and the specific energy absorption of CSH is increased by 1.84 times and 0.75 times, respectively.

     

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