Assessment of external dynamics and internal mechanics in ship collisions

The paper compares two methods based on finite element simulations to assess the external dynamics and the internal mechanics in ship collisions. One method treats independently the external dynamics and the internal mechanics (decoupled method), while the other one couples their interaction (coupled method). In the decoupled method, the external dynamics are evaluated by the analytical approach of Pedersen and Zhang (1998), and the internal mechanics are assessed by simulations performed with the LS-DYNA finite element solver. In the coupled method, both the external dynamics and the internal mechanics are evaluated directly by numerical simulations that follow the model of Pill and Tabri (2011). The two methods are compared to determine the differences in predicting the deformation and rupture of the collided ship structures and to assess the relationship between the structural deformation energy of the struck ship and the energy loss of the striking ship. The objective of the paper is to verify whether the decoupled method satisfies the predictions required for design appraisal assessments. The paper also illustrates the influence of the collision angle on the mechanics of ship collisions.