Further study on strain growth in spherical containment vessels subjected to internal blast loading

Strain growth is a phenomenon observed in the elastic response of containment vessels subjected to internal blast loading, which is featured by the increased vibration amplitude of the vessel in a later stage. Previous studies attributed the strain growth in spherical containment vessels to the structural perturbation, the beating between two close vibration modes and the interactions between the vessel vibration and the reflected shock waves. In this paper, it is shown that nonlinear modal coupling is another important cause of strain growth in spherical containment vessels. Based on the understanding of the vibration modes in a complete spherical shell, the nonlinear modal coupling in the nonaxisymmetric response of complete spherical shells are studied using finite element method. Methods for preventing the strain growth due to nonlinear modal coupling are discussed, which provide guidelines for the engineering design of spherical containment vessels.