Mechanical Modeling And Characteristic Analysis Of Compression Of Thin-walled Tube And Honeycomb-filled Structure

Metal thin-walled tube and its honeycomb-filled structure generate severe plastic deformation under continuous compressive load,which can dissipate the kinetic energy by converting it into plastic deformation energy.Thin-walled structures are widely used in the energy absorption systems in the fields of automobile,rail transit,aerospace and so on.In the early years,scholars carried out a lot of experimental and theoretical research on conventional square tubes and circular tubes.In recent years,in order to obtain better energy absorption performance,the research on thin-walled tubes has been extended to origami tubes,multi-corner tubes(polygonal tubes),multi-cell tubes,bellows and so on.Metal honeycomb is a kind of porous material with regular periodic structure,and has the advantages of high strength and high specific energy absorption.Filling honeycomb into thin-walled tube can not only avoid the local damage and overall collapse of the honeycomb,but also improve the energy absorption performance of the thin-walled tube.In this paper,the axial quasi-static compression characteristics of different kinds of thinwalled tubes and their honeycomb-filled structures are studied,and the results provide theoretical basis and guidance for the application of them in various energy absorption systems.A pre-folding tube that can induce extension deformation is proposed.The mechanical model of the deformation of the pre-folding tube is established,and the theoretical prediction formula of the mean crushing load is deduced based on the basic folding element theory.A kind of multi-cell tube with multi-corner is also proposed.Based on the simplified basic folded element theory,the theoretical prediction formula of the mean load of the multi-cell tube is also derived.The theoretical method can be applied to derive the mean load of multi-cell tubes with different side wall lengths.The finite element models of the axial quasi-static compression of the three kinds of tubes are establisd.The pre-folding tubes and multi-cell tubes with different geometric parameters and thickness are simulated and analyzed to study the effects of geometric parameters and thickness on their deformation and energy absorption performance.The specimens of square tube,pre-folding tube and multi-cell tube are made,and experiments of the three kinds of tubes are carried out.The theoretical values of the mean load are calculated and compared with the simulation results to validate of the theoretical prediction formula.The finite element models are validated by comparing the experimental results and simulation results.The finite element models of quasi-static compression of three kinds of honeycombfilled structures: honeycomb-filled square tube,honeycomb-filled pre-folding tube and honeycomb filled multi-cell tube are establisd.The quasi-static compression of honeycomb-filled structures composed of square tubes different thickness and honeycomb with different strength,pre-folding tubes with different geometric parameters and honeycomb with different strength,and multi-cell tubes with different geometric parameters and honeycomb with different strength were simulated.The effects of geometric parameters and wall thicknessof thin-walled tubes,and strength of honeycomb on the deformation and energy absorption performance of the filled structures are analyzed.The theoretical relationship between the mean load of the honeycomb-filled structure,the mean load of the thin-walled tube and the mean load of the honeycomb is fitted by the least square method.Finally,the relationship between the mean load of the honeycomb-filled structure and the geometric parameters and thickness of the thin-walled tube and the geometric parameters of the honeycomb cell is obtained by substituting the theoretical prediction formula of the mean load of the thin-walled tube and the theoretical formula of the honeycomb strength.The experimental results and simulation results are compared to validate the finite element models and the theoretical values of the mean load are calculated and compared with the simulation results to validate of the theoretical prediction formula.The performance of three honeycomb-filled structures under dynamic impact is analyzed,and the dynamic coefficient of mean load is obtained.Based on the theoretical prediction formula of the mean load of the three kinds of honeycomb-filled structures,the optimization design of the three kinds of honeycomb-filled structures is carried out with the geometric parameters and wall thickness of the thin-walled tube as independent variables,the mean load and energy absorption as constraints,and the maximum specific energy absorption as the optimization objective.The dynamic impact simulation analysis of the three optimized honeycomb-filled structures is carried out.The energy absorption performance indices are analyzed,and the corresponding energy absorption performance parameters are calculated according to the load-displacement curves obtained from the simulation analysis of three kinds of honeycomb-filled structures.The energy absorption performance,envelope size,mass of the three kinds of honeycomb-filled structures are comprehensively compared and analyzed,which provides guidance for the optimal design and type selection of the energy absorption device.