A hydroelastic vibration analysis of a container ship using finite element and boundary element methods

This paper presents a hydroelastic investigation of a container ship using the finite element and boundary element methods. The hydroelasticity method adopted in this study has two parts: dry and wet analysis parts. In the dry analysis part, a finite element model of the entire ship structure was prepared using the ABAQUS finite element software, and the in vacuo dynamic properties (natural frequencies and associated mode shapes) of the structure were obtained. In the wet part of the analysis, it is assumed that the fluid is ideal, i.e., inviscid, incompressible and its motion is irrotational. The fluid-structure interaction forces are associated with the inertia effect of the surrounding fluid, and a boundary integral equation method was adopted for the calculations. The wetted surface of the ship hull was idealized using appropriate boundary elements. A higher order boundary element method was adopted in the present study. The fluid-structure interaction forces were calculated solely in terms of the generalized added mass coefficients. In order to assess the influence of fluid on the dynamic response characteristics, the wet frequencies and associated wet mode shapes were calculated. The wet frequencies obtained from the method of analysis were compared with those obtained from the ABAQUS finite element software. A very good comparison was obtained between the calculations.