A Comparative Study Of The Effects Of Foam Filling And Connecting Ribs On The Energy Absorption Characteristics Of Multi-Cell Thin-Walled Structures

In recent years,metal thin-walled structures have been widely used in national defense and military fields due to their lightweight and efficient energy absorption characteristics.Studies have shown that thin-walled tubes with the same volume and different cross-sectional shapes have the strongest energy absorption capacity under axial impact.However,the diameter-thickness ratio and length-diameter ratio of the structure greatly affect the deformation mode of the structure.Among them,foam filling can significantly improve the deformation mode of the thin-walled structure and improve the energy absorption efficiency of the structure,but the specific energy absorption of the structure after foam filling will be reduced.In order to improve the specific energy absorption of the structure,the coupling of different levels of cell tubes is realized by introducing the internal structure into the ribs,and the energy absorption characteristics of foam filling and multi-celling after parameter matching are further explored.（1）In order to compare the effects of foam filling and rib connection on the dynamic response of multi-cell thin-walled structures（MTS）,high-speed（30-70m/s）mass impact tests were carried out on hollow thin-walled structure MTS,polyurethane foam（PUR）filled MTS（FMTS）and 2nd order MTS(MTS-2^nd).Based on the experimental and numerical results,the dynamic enhancement mechanism of energy absorption of three thin-walled structures is discussed.The results show that the dynamic enhancement coefficients（DEC）of the mean crushing force（MCF）of the empty thin-walled structure MTS and FMTS are 1.07-1.23 and1.08-1.33,respectively.Compared with quasi-static compression,the total energy absorption（EA）of MTS is 11.4-26.32%,FMTS is 13.83-32.52%,and the dynamic enhancement of MTS-2^ndis 4.3-9.68%.The multi-cellularization tends to reduce the sensitivity of MTS to the crushing force of the loading rate,while foam filling increases the sensitivity of energy absorption to the rate.（2）Combined with previous experiments,a new type of high g-value loading device was developed,and the aluminum cone was selected as the shaper.Based on the hybrid filled multi-cell structure of bionic and multi-cell design,the structure was subjected to high g-value impact experiments at different speeds,and the reliability of the experiment was verified by simulation comparison.Finally,the high g-value optimization design of response acceleration and specific energy absorption is carried out for three kinds of mixed-filled multi-cell thin-walled structures with different inner diameters.Finally,the Pareto optimal solution set of high g-value impact multi-cell thin-walled structures is obtained.（3）Based on the bionic structure such as lotus leaf,three new multi-cell thin-walled structures are designed.Through numerical comparison,the cross-section evolution of two better structures at different levels is carried out,and the numerical results are verified by theory.The BMTS3 structure with a cell number of 6 and better energy absorption was filled with foam,and the energy absorption characteristics of the structure under three foam fillings were compared by increasing or decreasing the ribs.