Hydro-elastic-plastic dynamic response of a ship hull girder subjected to an underwater bubble: Fid-Bau Portal

Hydro-elastic-plastic dynamic response of a ship hull girder subjected to an underwater bubble

Zhang, N. / Zong, Z.

Abstract Dynamic hydro-elastic-plastic response of a floating ship hull girder subjected to an underwater explosion bubble is studied in this paper. A fluid-structure analysis is given to consider the effect of a gas bubble acting on the hull girder. The bubble dynamic equations with the bubble's migration, free surface effect and drag force taken into consideration are numerically solved using Runge–Kutta method. The elastic and plastic responses of a hull induced to a bubble impulsive pressure are calculated using a method presented herein. Resonance mechanism in hull girder's whipping response to an underwater bubble is discussed in detail. The formation of the plastic hinge when the hull girder's longitudinal bending moment exceeds its ultimate bending moment is investigated. Real-scale ship examples are given to discuss the features of the dynamic elastic and plastic response.

Highlights ► We establish a model of both an underwater bubble and an elastic–plastic ship hull girder. ► Resonance phenomenon will happen when the bubble pulsating frequency is close to the ship hull's low-order eigenfrequency. ► Smaller charge weight can make much larger bending moment when resonance happens. ► A single plastic hinge will form when the hull girder's longitudinal bending moment exceeds its ultimate bending moment. ► The plastic deformation of the hull girder features a sharp rise and a short duration.