Energy Absorption Of Bio-inspired Multi-layer Graded Foam-filled Structure

In a series of engineering fields such as aerospace,transportation,nuclear reactor and civil engineering,the demand for light structures with high energy absorption capacity is incrrasing.Therefore,the availability of lightweight structures with excellent energy absorption capacity is very important for many engineering applications.Inspired by many biological structures in nature,bio-inspired structures have significantly improved energy absorption capacity compared with traditional structures.Therefore,using bio-inspired method to design new lightweight structure with excellent energy absorption ability has become a research hotspot in the field of Engineering in recent years.In this paper,a new bio-inspired multi-layer graded foam-filled structure(MGFS)was proposed,which was inspired by the layered and dense characteristics of human bones.The energy absorption characteristics of bio-inspired MGFS under quasi-static axial compression were systematically studied by means of experiments,theory and numerical simulation.Firstly,a theoretical formula was cited to predict the average br EAking force of bio-inspired MGFS,and the predicted results were in good agreement with the experimental results.Then the finite element analysis of the experimental model was carried out.The finite element analysis showed that Model-1(the density of foam was 250 kg/m3,400 kg/m3,550 kg/m3 from inside to outside)was the best combination.Compared with the traditional foam filled structure,bio-inspired MGFS had better energy absorption properties.The results of finite element analysis were in good agreement with the experimental results.The parametric study showed that the length,diameter,thickness of the aluminum tube and the density of the aluminum foam had a significant effect on the energy absorption ability of the bioinspired structure.However,when the aspect ratio was less than 2,the SEA and Pm of bio-inspired MGFS were not sensitive to the change of length.The energy absorption characteristics of two types of bio-inspired MGFSs under quasi-static lateral compression were also studied.Numerical simulation showed that Model-2(the density of foam was 250 kg/m3,550 kg/m3,400 kg/m3 from inside to outside)in Case-1 had the highest SEA and Pm,and Model-6(the density of foam was 550 kg/m3,400 kg/m3,250 kg/m3 from inside to outside)in Case-2 also had the highest SEA and Pm,which showed that the configuration of these two models were the best combination for the design of energy absorbers with high energy absorption capacity.The parametric study showed that the thickness,diameter of aluminum tube and the density of aluminum foam will affect the energy absorption index SEA and Pm of bioinspired MGFS.This study have provided effective guidance for designing foam filled energy absorber with high energy absorption efficiency.