Dynamic Response Of Sandwich Tubes With Graded Foam Aluminum Cores Under Internal Blast Loading

The porous metal sandwich structure is widely used in vehicles,shipbuilding,nuclear industry and other engineering fields due to its advantages such as low density,high specific strength,high specific stiffness and excellent energy absorption performance.The sandwich structure may undergo large plastic deformation even causes structural damage under the blast loading.Therefore,it is necessary to understand the mechanical behavior of sandwich structure under blast loading.The dynamic response of sandwich tube subjected to blast loading was investigated numerically.The 3D-Voronoi technology was introduced to establish three-dimensional mesoscopic finite element model of aluminum foam.The main work is as follows:(1)Based on the 3D-Voronoi technology,a three-dimensional mesoscopic finite element model of the aluminum foam core layer was constructed,and the relative density of the core layer was characterized by the cell size or cell wall thickness.The influence of core constructed by these methods on sandwich tube structure deformation and energy absorption performance were investigated.The research results show that the core layer constructed by changing the cell size or cell wall thickness has the same deformation and energy absorption effect on the inner and outer tubes of the sandwich tube.(2)The LS-Dyna software was used to study the deformation and energy absorption performance of the sandwich tube under internal blast loading.Keeping the total mass of the sandwich tube unchanged,the effects of the wall thickness of the inner and outer tubes of the sandwich tube on its deformation and energy absorption performance were analyzed.And the influence of the thickness of the foam core,the relative density of the foam core and explosive charge on the dynamic response of the sandwich tube under internal blast loading were studied.The deformation process of sandwich tube can be simply divided into three stages,the interaction between the blast loading and the inner tube,the core densification,and the outer tube deforming.When the total mass of the inner and outer tubes were constant,the increase of the inner tube thickness can effectively reduce the deformation of the inner tube and weaken the energy absorption of sandwich tube.The deformation of the outer tube first decrease and then increase.As the relative density of the core increases,the deformation of the inner tube decreases and the deformation of the outer tube increases.As the thickness of the core increases,the maximum deformation of the outer tube decreases,the energy absorption of the foam core increases.(3)The deformation and energy absorption of sandwich tube with two-layer core were analyzed,including positive gradient sandwich tube,negative gradient sandwich tube and uniform core sandwich tube.For sandwich tube with two-layer core,the deformation modes of positive gradient sandwich tube and negative gradient sandwich tube were different.Under the internal blast loading,the foam core layer of the negative gradient sandwich tube was gradually laminated from the inner tube to the outer tube.After the inner foam core layer of the positive gradient sandwich tube was partially compacted,a part of the outer foam core layer was compacted at the junction of the two foam core layers,and then the two core layers were simultaneously compacted.Among the three groups of gradient sandwich tubes,the blast resistance of the positive gradient sandwich tube was the best.Increasing the density difference of the layer of the positive gradient sandwich tube can reduce the deformation of the outer tube;reducing the thickness of the inner foam core layer can improve the blast resistance of the positive gradient sandwich tube.(4)The deformation and energy absorption of sandwich tubes with three-layer core under internal blast loading were studied,the effects of six arrangements of three different relative density foam core and four arrangements of two different relative density foam core on the blast resistance and energy absorption of the sandwich tube structure were analyzed and the effects of the relative density difference and the thickness of the foam core were considered.For sandwich tube with three-layer core,when the core layer was composed of three types of foam aluminum,the structure with a medium-high-low relative density arrangement of foam core has the best energy absorption performance;when the core layer was composed of two types of foam aluminum,the blast resistance of the structure with a low-high-low relative density arrangement of foam core was better than that of sandwich tube with a high-low-high relative density arrangement of foam core.