Cumulative Damage Effect of Hull Girder Subjected to Multiple Underwater Explosions

To explore the accumulative damage problem of the hull girder subjected to multiple underwater explosions, the influences of explosive equivalent, stand-off distance, and the number of explosions to the hull girder were studied by ultilizing of AUTODYN software together with testing methods. The results show that under underwater explosive loadings, there are two deformation modes, i.e., local plastic deformation of middle depression and plastic bending deformation of global hogging. At a certain shock factor, the deflection values change linearly with the loading times of multiple underwater explosions, and they increase with the increase of explosive charge. The final deflection values of hull girders are different between the cases subjected to single and those to uniform three consecutive underwater explosions under the same stand-off distances and equivalent charges. The deflection values of hull girders decrease subjected to three-time uniform explosions, and are only half of the deflection values under single-time explosion loadings.