Coupled Analysis of External Dynamics and Internal Mechanics in Ship-Floating Bridge Collision Studies

Ship collisions with floating bridges in the navigation area are complex processes involving highly nonlinear dynamics, large structural deformations, and fluid-structure interactions (FSI). In the traditional approach for collision analyses, the external dynamics and internal mechanics of the ship-bridge system are treated independently. Limitations have been reported for this decoupled method in predicting the structural responses during oblique collisions. This study introduces an algorithm to integrate the external dynamics and internal mechanics in ship-floating bridge collision studies, addressing the complexities of a multibody system. The external dynamics of a traveling ship colliding with a floating bridge is modeled using OrcaFlex, while the internal mechanics is simulated in LS-DYNA. Through the developed algorithm, two analyses are conducted interactively. The algorithm incorporates the considerations of hydrodynamic forces acting on the floating bodies, their six degrees of freedom (6DOF) motions, and the structural internal forces within the multibody system. The simulation results reveal that the collision forces, effective stress, plastic strain of the striking ship and the struck pontoon, as well as the energy dissipation, are sensitive to the boundary conditions applied to the pontoon.