Experimental Investigation of the Second Critical Velocity of Dynamic Buckling of a Cylindrical Shell under Axial Impact

In the present paper, experimental investigations on dynamic plastic buckling of cylindrical shells under axial impact are carried out. By using a gas gun the experimental studies on dynamic bucking of copper and steel cylindrical shells under axial impact are given. With different velocities, the axisymmetric shaped, non-axisymmetric oval-shaped and triangle-shaped buckling modes are found in the experiments. The first critical velocity and the second critical velocity are defined according to the different buckling modes. The corresponding critical energy is also defined. Strain measurement results show that the strain rate reverse occurs even if the impact velocity is lower than the second critical velocity. This result is different from the hypothesis given by the former investigators. Some new buckling phenomena including the local buckling are also obtained in the present experiments.