New method for determining the second critical speed of thin-wall cylindrical shells under axial impact

Studying on dynamic buckling modes of thin-wall cylindrical shells is helpful to design anti-impact structures. There exists a secondary critical speed beyond which the axisymmetric buckling mode of a thin-wall cylindrical shell under axial impact would be converted a nonaxisymmetric one, moreover when the axial impact speed is beyond the second critical speed, the axisymmetric buckling mode appears firstly, and then the buckling mode changes to the nonaxisymmetric one gradually with the impact response time. According to the theory described above, by comparing the time histories of the kinetic energy and the buckling deformation based on the finite element model of the impact system, an energy iterative method to determine the second critical speed is presented. Using this new method to design anti-impact structures of the thin-wall cylindrical shell can reduce test times and cost effectively. The feasibility and validity of this method are demonstrated by a dropping hammer experiment.