Hydroelasticity analysis of a container ship using a semi-analytic approach and direct coupling method in time domain
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A three-dimensional semi-analytic method in time domain is used to predict the hydroelastic effects due to wave-induced loads on a container ship. A container ship with zero forward speed has been taken to perform the hydroelastic analysis. The pertinence of the proposed method is verified with the results obtained from the direct coupling between FEM and BEM in time domain. In both the approaches, the proposed structure has been modelled as an Euler–Bernoulli beam. However, in case of the semi-analytic approach, the container ship has been assumed as an equivalent rectangular barge with uniformly distributed mass. The hydrodynamic forces are obtained in time domain through impulse response function. The Duhamel integral is employed in order to get the structural deflections, velocity, etc. The hydrodynamic and structural part is then fully coupled in time domain through modal analysis to capture the proper phenomena. On the other hand, in case of the direct coupling, a 3D time domain lower order panel method is used for the solution of the hydrodynamic problem. Structural responses, shear forces and bending moments are calculated at different sections of the ship. The validation of the computed results is confirmed as satisfactory agreement is found between these two methods. It may be noted that the present semi-analytic technique appears to be time efficient, robust and could be a very useful tool in predicting the hydroelastic effects on a container ship in terms of shear force, bending moment, structural deflection at initial design stage.