星形节点周期性蜂窝结构的面内动力学响应特性研究

摘要

The in-plane dynamic impact response behaviors of periodic 4-point star-shaped honeycomb structures were numerically studied by means of the explicit dynamic finite element (EDFE) simulation method.Under the promise of cell element's wall length keeping unchanged,the FE model of periodic 4-point star-shaped honeycombs was established by changing micro-cell structure parameters including cell wall thickness,angle between inner concave arrow nodes,and ligament length.Then the influences of impact velocity and micro-cell structural parameters on in-plane macro-/micro-deformation behaviors,densification strains and dynamic impact intensities of star-shaped honeycombs were discussed in detail.The results showed that the specimens reveal a "necking" phenomenon of negative Poisson ratio materials under impact loading with low ormoderate velocity,it is mainly due to cell walls bear the combination of membrane force and bending moment;based on the energy absorption efficiency method and the one-dimensional shock wave theory,empirical formulae for densification strain and dynamic plateau stress of the honeycombs were deduced to predict the dynamic load-bearing capacity of star-shaped honeycombs.The results provided a new idea for the multiobjective optimization design of dynamic impact properties of stretch cell materials.%利用显式动力有限元法数值研究了冲击载荷下星形节点周期性蜂窝结构的面内冲击动力学响应特性.在保证各胞元壁长不变的前提下,通过改变胞壁厚度、内凹箭头节点间夹角和韧带长度等微结构参数,首先建立了星形节点周期性蜂窝结构的有限元模型.在此基础上,讨论了冲击速度和微结构参数对星形蜂窝材料的宏/微观变形、密实应变和动态冲击强度的影响.结果表明,由于胞壁受膜力和弯矩的耦合作用,在中、低速冲击载荷下,试件表现出负泊松比材料在轴向压缩时的“颈缩”现象.基于能量效率法和一维冲击波理论,给出了星形蜂窝结构密实应变和动态平台应力的经验公式,以预测多胞材料的动态承载能力.该研究将为拉胀多胞材料冲击动力学性能的多目标优化设计提供新的设计思路.