金属多级类蜂窝的压溃行为研究

通过实验和数值模拟方法系统研究了单胞壁开孔金属多级类蜂窝与双胞壁开孔金属多级类蜂窝的压溃行为. 重点分析了试件尺寸、开孔位置、孔偏距和孔梯度等因素对多级类蜂窝力学性能的影响. 结果表明,多级类蜂窝的压溃过程可分为3个阶段:弹性变形、屈曲变形以及密实;单胞壁开孔多级类蜂窝的压溃过程趋向于渐近内凹压溃,而双胞壁开孔多级类蜂窝趋向于轴向压溃;试件尺寸对多级类蜂窝的力学行为有明显的影响,当胞元数达到一定数目时,其力学性能几乎与蜂窝胞元数无关. 单胞壁开孔多级类蜂窝的峰值应力大于双胞壁开孔多级类蜂窝的峰值应力,但其平均压溃应力小于双胞壁开孔多级类蜂窝的平均压溃应力;与传统蜂窝相比,蜂窝胞壁开孔设计降低了蜂窝材料的比吸能;孔偏距的存在导致单胞壁开孔多级类蜂窝的峰值应力降低,但随着孔偏距的增加其平均压溃应力呈先减低后增加趋势;多梯度孔设计对多级类蜂窝材料的力学性能有重要影响,与均匀孔多级类蜂窝相比,正梯度孔分布设计降低了多级类蜂窝峰值应力,但提高了其平均压溃应力;多梯度孔分布设计对多级类蜂窝的峰值应力和平均压溃应力影响不大. 

INVESTIGATION ON CRUSHING BEHAVIOR OF METAL HONEYCOMB-LIKE HIERARCHICAL STRUCTURES1)

Crushing behavior of metal honeycomb-like hierarchical structures of perforations on single walls (HHSPSW) and double walls (HHSPDW) was systematically investigated by using experiment and numerical simulation methods. Effects of specimen size, perforation location, perforation offsets and perforation gradient on the mechanical properties of honeycomb-like hierarchical structures were analyzed. The results show that the crushing process of honeycomb-like hierarchical structures can be divided into three deformation stages: elastic deformation, buckling deformation and densification. The deformation mode of honeycomb-like hierarchical structures of perforations on single walls is a progressive concave mode, while honeycomb-like hierarchical structures of perforations on double walls deform by axial crushing mode. Specimen sizes have significant influences on mechanical behavior of honeycomb-like hierarchical structures. Mechanical properties are almost independent of honeycomb numbers attaining a certain number. The peak stress of the honeycomb-like hierarchical structures of perforations on single walls is greater than that of honeycomb-like hierarchical structures of perforations on double walls, while its mean crushing stress is less than that of honeycomb-like hierarchical structures of perforations on double walls. Comparing to the traditional honeycombs, the design of perforations on honeycomb walls reduces the specific energy absorption of the honeycombs. Perforation offsets result in decreasing the peak stress of the honeycomb-like hierarchical structures of perforations on single walls, while the mean crushing stress firstly decreases and then increases with increasing the perforation offset. Honeycomb-like hierarchical structures with positive gradient perforations reduce the peak stresses while improve the mean crushing stress comparing to honeycomb-like hierarchical structures with the uniform perforations. The design of muti-gradient perforation distributions on honeycomb walls has small influence on the peak stress and the mean crushing stress.