Research On Impact Characteristics Of The Self-similar Gradient Hierarchical Quasi-honeycomb

As a typical representative of porous composite materials,honeycomb structures have many advantages such as lightweight,high specific strength,and specific rigidity.It has been widely used in many critical fields such as aerospace,automobiles,ships,and armor protection.Due to the existence of a large number of cavities inside the honeycomb structure,it exhibits superior energy absorption and buffering performance when suffer an impact load.From the perspective of bionics,this paper proposes a new type of self-similar gradient hierarchical quasi-honeycomb and study on the in-plane and out-of-plane impact characteristics using numerical simulation,theoretical analysis and experimental verification.It specifically analyzes the hierarchical order and gradient distribution's influence on the impact characteristics under different impact loads.In the study of in-plane impact characteristics,this paper firstly established the in-plane impact finite element model of the self-similar gradient hierarchical honeycomb structure and analyzed the hierarchical order's influence on the impact characteristics.It is found that the energy absorption efficiency will increase and the peak crushing force will decrease with hierarchical order's growth.Subsequently,this article discussed the in-plane gradient distribution's influence on impact characteristics,and found that a reasonable gradient distribution can further reduce the initial peak crushing force,but it also causes the in-plane energy absorption to have a slight decline.In terms of out-of-plane impact characteristics,this paper firstly researched the hierarchical order's influence on the out-of-plane impact characteristics.Based on the simplified super folding theory,an out-of-plane impact theoretical model for the self-similar gradient hierarchical honeycomb structure was established,and then the influence of cells number and structure size on out-of-plane impact characteristics was further discussed based on the theoretical model.Finally,the influence of the out-of-plane gradient distribution on the impact characteristics was discussed.Research found that the hierarchical design described in this article has a certain improvement in the out-of-plane impact performance of the honeycomb structure,and the gradient distribution can greatly reduce the out-of-plane impact peak crushing force,but it also can significantly reduce the energy absorption efficiency of the structure.Filling the traditional crash box with the self-similar gradient hierarchical honeycomb and a new kind of self-similar gradient hierarchical honeycomb-filled crash box was designed.This paper studied the axial impact characteristics of the new-type crash box and compared with the traditional crash box through numerical simulation.It is found that the new-type honeycomb-filled crash box has a great improvement in energy absorption efficiency and load efficiency than the traditional crash box,and this advantage will increase with the hierarchical order's growth.