Study On Energy Absorption Capacity Of Regular Polygon-based Multi-cell Thin-Walled Tubes Under Axial Load

Multi-cell thin-walled structure is an excellent energy-absorbing structure with lots of outstanding characteristics,such as light weight,high specific strength,high specific energy absorption,low cost,etc.,which is widely used in the anticollision system of aircraft,automobiles,ships and vehicles.In general,the axial deformation of thin-walled structure is stable,and the energy absorption is about an order of magnitude higher than that of the transverse deformation.Therefore,the energy absorption characteristics of thin-walled structures under axial loading is the emphasis of research in this field.By summarizing the previous research results,this paper designed several kinds of regular polygon-based thin-walled structures,and analyzed the deformation mode and energy absorption characteristics of multi-cell thin-walled tubes under axial load by experiment and simulation.The main contents are as follows:(1)based on the regular polygon structure,the first kind of first-order structure was constructed by connecting the centroid with each vertex.On the basis of the first-order structure,two kinds of new second-order multi-cell thinwalled structures were designed by embedding polygons and adding circular tube.By quasi-static and dynamic impact tests,we analyzed the deformation mode and the energy absorption parameters;(2)based on the regular triangle,the second kind of first-order structure was constructed by embedding regular triangle,and then the second-order structure was obtained by embedding the triangle again.The impact tests were carried out on two structures of different orders,and the finite element models of the two structures were established by ABAQUS finite element software.Finally,the simulation results were compared with the experimental results;(3)on the basis of the second kind of first-order structure,different polygons(triangle,quadrangle,pentagon,hexagon)were embedded into the structure.Using finite element simulation for parametric study,including wall thickness and diameter,the effects of them on the energy absorption characteristics of structures were discussed.The research results of this paper are as follows:(1)the deformation of the first type second-order structure was stable;When expanding with the same structure,the energy absorption performance of the polygon-embedded structure is obviously better than that of the circular-tube-added.(2)the experimental results were compared with the simulation results,including the deformation mode and energy absorption parameters.The results showed that the results of the two research methods were consistent with each other,which verified the effectiveness of the finite element simulation;(3)By simulating and comparing the structures of different orders of the second type,it can be concluded that:1)when the second-order substructure is hexagon,the energy absorption performance has obvious advantages over the other three methods;2)the change of wall thickness has different effects on different structures: as the outer wall thickness increases and the inner wall thickness decreases in first-order structure,the energy absorption performance of the first-order structure with embedded triangle decreases gradually,while the energy absorption of the first-order structure with embedded hexagon does not change significantly.For second-order structure,the difference in the energy absorption performance of the outer wall thickness of 0.4 mm,0.8 mm and 1.0 mm is small,while the energy absorption of the outer wall thickness of 1.2 mm decreased significantly;3)when the side length of the outer triangle is within the range of 50 mm～80 mm,with the increase of the aperture,the peak force of the first-order structure of the embedded triangle and hexagon increases continuously,the total energy absorption changes little,and the specific energy absorption decreases gradually.