胞元缺失对六边形蜂窝共面缓冲性能的影响

目的研究胞元缺失的分布位置和大小对六边形蜂窝结构共面缓冲性能的影响。方法利用有限元分析软件Ansys/LS-DYNA建立六边形蜂窝在共面动态压缩载荷作用下可靠的动力学计算模型,动态压缩的速度在100 m/s以下。由计算结果进一步分析得到缓冲性能各评价指标。胞元缺失在样品中的分布位置根据其对称性有6种情形,针对单元缺失居于样品中央的情形,研究缺失大小对性能的影响。结果中低速冲击时,胞元缺失降低了结构的密实化应变值;高速冲击时,胞元缺失会增加六边形蜂窝结构的密实化应变。随着壁厚的增加,缺失位置对动态峰应力的影响先增大后减小。与完整六边形蜂窝相比,胞元缺失使得单位质量能量吸收随着应变的增加呈先大于后小于完整蜂窝单位质量能量的变化趋势,且随着冲击速度的增加,这种变化趋势越明显。在低速冲击下对于任一缺失类型,随着胞元缺失数目的增加,单位质量能量吸收明显减弱。结论相较于胞元缺失的分布位置,胞元缺失尺寸对六边形蜂窝共面缓冲性能的影响更大。

Influence of Cell Defects on the In-plane Cushioning Property of Hexagonal Honeycomb

The work aims to discuss the effect of cell defect distribution location and its size on the in-plane cushioning property of regular hexagonal honeycomb cores (RHHCs). Based on the finite element analysis software Ansys/LS-DYNA, a reliable dynamic calculation model of RHHCs under the action of in-plane dynamic compression load was established, and the velocity of dynamic compression was below 100 m/s. Evaluation indicators of cushioning property were obtained by further analysis on the computed results. There were six kinds of cell defect distribution locations in the specimens because of their symmetry. The effect of the defect size was studied in the case of missing cell clustering in the center of the specimen. The cell defect reduced the value of densification strain for the intermediate/low-velocity impact and increased such value of the RHHCs for the high-velocity impact. With the increase of cell wall thickness, the influence of defect location on the dynamic peak stress first increased and then decreased. The cell defect made the energy absorbed per unit mass show the trend of being less after being greater than the complete honeycomb unit mass energy which was increasingly obvious with the increase of velocity. At low-velocity impact, the value of the energy absorbed per unit mass decreased significantly with the increase of the number of missing cells for any defect type. Compared with the cell defect distribution location, its size has a greater effect on the in-plane cushioning property of RHHCs.