Numerical simulation of structural collapse of container ship in waves based on two-way coupling of CFD nonlinear FEM

The structural response and dynamic structural collapse mode of a container ship in waves are studied by fully considering the effects of load nonlinearity and surface nonlinearity.

First, a hydrodynamic model of a container ship is established based on the CFD platform, and the overset grid method is used to realize matching between the dynamic boundary grid of the hull hydrodynamic model and the Euler grid in the far-field fluid domain. The volume of fluid method is used to simulate the nonlinearity of the free surface in the whole fluid domain, and the N–S equations in three directions are solved in the whole flow field domain so as to solve the nonlinear wave load of the ship in real time. A nonlinear finite element model of the ship that can simulate its collapse behavior is then established, and the time-domain collapse response of the ship including plasticity and buckling is calculated based on the explicit dynamic nonlinear finite element method (FEM). Finally, the transmission of fluid pressure and node displacement between the hydrodynamic model and structural finite element model on the wet surface are realized, and two-way iterative coupling between the CFD solver and nonlinear finite element solver is carried out to calculate the nonlinear wave load and structural collapse response during the structural collapse of a 4600 TEU container ship in real time.

Under extreme waves, the upper to middle structures of the container ship are widely plastic, the main deck, side plate, deck longitudinal, side longitudinal and other components have typical yield instability under the action of wave loads, the deck longitudinal, side longitudinal and other structural members have serious lateral instability, and the hull structure loses its bearing capacity.

The proposed CFD nonlinear FEM can accurately solve the structural response and dynamic collapse mode, making it viable as a new approach to studying the collapse response of ship structures.