Dynamic response analysis of spherical pressure hull implosion inside adjacent underwater structure

The implosion will occur when the pressure hulls have a geometric imperfection or are impacted from the outside, which could cause the collapse of submerged vessels. In this work, the open-source finite element solver OpenRadioss is used to analyze the implosion caused by the failure of the spherical pressure hull and the interference with the adjacent cylindrical shell in the double-hulled cabin of a submarine. Firstly, the implosions of the cylindrical tube and destruction of the spherical pressure hull are compared with experimental results. Secondly, the underwater implosion of the sphere is analyzed inside a cylinder with local impacts in different induced directions. The results found the flow field and structural deformation show obvious directivity, in which the deformations of the cylindrical shell are mainly caused by the absorption action instead of the shock wave effect when implosions occur in the direction closer to the cylinder. Finally, the dynamic responses of implosions are discussed under different triggering modes and hydrostatic pressures. We found that the structural deformation and energy evolution are similar when the sphere is subjected to a collapse load. However, the effect of triggering modes gradually becomes larger with the increase of hydrostatic pressure.