Dynamic Response of the Bow Flare Structure Under Slamming Loads

Abstract

To increase the loading capacity of large ships, the flared bow is usually adopted to ensure adequate deck area to arrange the goods or weapons, however, this type of bow structure also results in serious bow flare slamming loads. In recent years, the local structural damages of ships that were caused by local slamming loads have been heard by accident, so it’s very necessary to study on the local slamming pressure loads and structural response assessment. The ship in its whole life may encounter all kinds of wave conditions and designers are very concerned about how to determine the design slamming loads on the flare structure. 3-D linear potential flow theory and long-term analysis method of the relative slamming velocity are combined to determine the design state for assessing the slamming strength of bow flare structures. During the specific calculation, the relative motion between the hull flare section and the wave surface is simplified as relative motion between the hull section and the static water surface. And an explicit finite element method is used to predict the slamming load when the hull flare section entries into the water. By adding the slamming pressure load of each time step to the finite element model and establishing the reasonable boundary conditions, the dynamic response prediction of the bow flare structure is achieved. The calculations of different gird size are carried out to verify the convergence of the method in this paper during the prediction of local slamming pressure and structural response. The assessment results of the direct calculation method and the society classification guide are discussed to better guide the bow flare structural design.