WHIPPING RESPONSE OF SHIP HULLS FROM UNDERWJATER EXPLOSION BUBBLE LOADING

r--A summary of the bubble pulsation dynamics of an underwater explosion is presented with the aim of establishing the whipping response of a nearby surface ship. The effects of the initial shock front are not considered and the fluid is assumed to be an incompressible medium. The gas bubble volume dynamics can then be related to far field fluid accelerations assuming that a potentia.l flow condition is satisfied, Given the effective mass of the ship comprising the added fluid and bouyancy mass contributions, the forces on the ship resulting from the accelerated flow field can be determined. The theory considers the effects of proximi~ty of the explosion bubble to a free surface, vertical migration of the bubble due to the hydrostatic imbalance, and an energy dissipative mechanism introduced via a pseudo pressure drag coefficient. The theory is applied in analyses of the whipping displacements and stresses induced in the hull of a typical frigate-size warship subjected to underwater blast loading. The response is obtained using a modal superposition of the wet hull modes of a detailed equivalent beam model of the hull. <-.-RisUM