Investigation Of Dynamic Response Of Aluminum Alloy Tubes Under Axial Impact

The thin-walled structure has been widely used in military, industrial aeronautic and astronautic fields,because it has a simple geometry and provides high specific energy and high volumetric efficiency.Due to the actual demand of structure’s impact absorbing energy and crashworthiness,the dynamic behavior of thin-walled structure subjected to axial impact load get people’s more and more attention.In this paper,dynamic stability of thin –walled structure is studied experimentally and numerically for various geometrical and impact parametes.The main work and conclusions are summarized as follow:(1) The dynamic loading experiments of thin-walled circular aluminium tubes with different materials and sizes are conducted by using the drop hammer and SHPB devices. The process is recorded by high speed camera. The results show that: the yield strength of pure aluminum is low, so the thin-walled circular tube with pure aluminum is crushed seriously. But due to the high elongation rate, the tube shows a petal shaped failure mode. The yield strength of LY12 aluminum alloy is high. The LY12 LY12 specimens are crushed with a cicumferential lobe under low impact velocity, while the speed is high, the bus crack appears on the shell wall, and with the propagation of the crack, the shell wall crushed. The thin-walled circular tubes with A6060 material mainly appeared dynamic progressive buckling in the experiments, showing non-symmetric triangular and quadrilateral buckling modes. In addition to the material, the diameter-thickness ratio and the length-diameter ratio of the thin-walled circular tube will also affect the collapse mode.(2) The dynamic response behavior of aluminium alloy thin-walled circular tubes subjected to axial impact load is studied numerically using LS-DYNA program, in order to investigate the influence of dimensions and impact kinetic energy on collapse mode and other response parameters. The results show that impact kinetic energy can affect the buckling mode of the specimens in addition to the geometry size and velocity. The process of large size thin-walled cylindrical shell impact the concrete target is studied numerically, and we can draw a conclusion that the shell begin to break out from the impact end under this condition.(3) In order to improve the bearing capacity of the thin-walled structure, the cylindrical shell are reinforced with ribs. The dynamic response of thin-walled stiffened cylindrical shell is studied numerically by LS-DYNA program. The results show that the critical load increases approximately linearly with the increase of the number of ribs. With the increase of the thickness, the response of the structure transforms from local instability to overall buckling. The response of the structure is elastic when the velocity is low, and along with the increase of the velocity, the structure occurs large plastic deformation. The repeated inner and outer convex of the shell wall and ribs respectively correspond to the peaks and troughs in the load curve.