The Buckling And Post-buckling Of Cylindrical Shell Under Axial Impact

Cylindrical shell is widely used in aviation,construction and other industries because of good mechanical performance.Cylindrical shell structures are often in instantaneous load and high speed impact dynamic environment in practical application.Dynamic buckling and failure of these structures have been the important research content in the thin-walled structure dynamic performance.From the application,the determination of crushing load about the cylindrical shell under axial impact has practical value;From the mechanics,the impact crush of cylindrical shell involves its elastic-plastic buckling and post-buckling.It is also affected with the inertia effect of structure and the strain rate effect of the material.The axial buckling and post-buckling of cylindrical shells under quasi-static were studied by scholars worldwide.Since it involves so many complex problems,many problems still need to be solved.Meanwhile the research about the buckling and post-buckling of cylindrical shells under high-speed impact is especially insufficient,and some research conclusions are lack of the support of experiment results and some conclusions from different researchers are inconsistent.It is necessary to carry out more comprehensive and more in-depth research and analysis.In consideration of the research status of cylindrical shell buckling under axial impact,this paper studied the crush of cylindrical shell under axial impact by experiment and FEA simulation.The static and dynamic experiments of cylindrical shell under axial load were carried out by using MTS and Hopkinson bar.The impact crushing experiments of cylindrical shells under different impact velocities were carried out under the condition of quasi-constant speed through the new design and modified Hopkinson bar apparatus and using the stress wave inversion technique.The deformations and velocity fields of cylindrical shell during crush were obtained by using highspeed photography with digital image correlation method(DIC).On the premise that the simulation results were verified by the experiment results,the occurrence,the development of buckling and post-buckling and the changing process of buckling geometry about cylindrical shell were further studied using finite element simulation.The results of the experiment and simulation show that the lateral inertia effect significantly influence the impact crushing force of cylindrical shell.The paper gives the influence of the shell sizes,impact velocity on the buckling and post-buckling of the cylindrical shell.Based on the experiment data,this paper gave the average crushing force empirical formula of cylindrical shell about the rate-independent material(aluminium alloy)using dimensional analysis and approximate decoupling.While considering the uniformity of deformation velocities of the cylindrical shell,the study also found that the symmetrical patterns are easily occurred in the area of high-speed deformation,while the asymmetrical patterns easily occurred in the area of low-speed deformation.To evaluate the effect of material strain rate on the influence of the cylindrical shell buckling modes and force,the rate related feature of brass and copper material was tested.Combined with the experiment results of impact crush,the preliminary analysis was carried out about the buckling modes and crushing load of cylindrical shell about the rate-dependent material.