Study on the whipping response of a stiffened cylindrical shell in an underwater explosion

The developmental process and the change laws governing the whipping response of a cylindrical model at different dive depths, different distances and directional angles from an explosive were investigated. The focus was on the case of a charge under the middle of the model. By making use of a large indoor explosion tube, it was possible to observe the processes effecting explosion bubbles and a model. The study combined applications of high speed photography and strain test technology. It was found that the response of the model could be resolved into rigid motion, where the response was dominated by flow delay, itself induced by bubble motion, and elastic vibration, which was dominated by the wet modal first-order vertical vibration. When the frequency of bubble impulses and the frequency of the model's vibrations were closest, the bubble impulse pressure and delay flow resonated with the model's shock vibration, thus producing the model's whipping response. The largest strain value could be 2-4 times the peak value of the shock wave's effects on the vibrational strain value. These results were effected by dive depth, distance to the explosion and the directional angle of the explosion.