Experimental and numerical investigation of ship structure subjected to close-in underwater shock wave and following gas bubble pulse

Abstract

One of the major topics confronted by the designers of naval vessels is to qualify the ship integrity exposed to underwater explosions (UNDEX). The far-field UNDEX & contact UNDEX problems are investigated by a few researchers previously. However, when a ship is subjected to close-in non-contact UNDEX environment, the failure mechanism of structures under the combined effect of shock wave load and bubble pulsations is rarely discussed. Thus, the dynamic response of ship structures subjected to close-in non-contact UNDEX is mainly concerned in this paper. Four UNDEX experimental tests of ship-type box structure (STBS, which can be fundamentally viewed as surface ships) are conducted in the study by using charge explosion. With reasonable finite element models, the coupled acoustic-structure algorithm in ABAQUS/Explicit code is utilized for the simulations. The wet vibration modes, accelerations, acoustic fluid pressure, and velocities from simulation results are compared with experimental data. The numerical simulation results agree well with those of experimental tests. Then, the detailed discussions are given to explore the damage processes of STBS subjected to the shock wave and bubble integrated loadings. The experiment and numerical simulation results reveal that global longitudinal strength collapse combined with the local wrinkling, the plastic deformation of hull between bulkheads and the plastic deformation of local bottom hull are the mainly three failure modes. And if the UNDEX bubble effects are not incorporated in the analysis, the damage severity will be underestimated. Moreover, other two practical numerical simulation examples are also discussed to illustrate the failure modes in depth.