Study on the assessment of absorbed energy of bulbous bow in ship collision

The evaluation of energy absorption characteristics of the bulbous bow structure in ship collisions or grounding accidents is a crucial research area. Predicting dynamic reactions or determining the collision energy absorption capability of the bulbous bow structure during impacts is essential in the design process. This paper investigates the collision behavior of the bulbous bow structure impacting a rigid wall using numerical simulations conducted with the commercial finite element code FEA. Namely, impact force histories on the bulbous bow structure, crushing depths/displacements, and collision energy absorption of the ship structure during impact are numerically determined under, consideration of different collision velocities, ship masses, impact angles and impact positions. The FEM results will be compared to results obtained from AASHTO. The results indicate that collision forces, deformations of the bulbous bow structure, and absorbed collision energies can be effectively predicted using current numerical simulation. The maximum collision force and energy absorption are directly influenced by the collision velocity and mass of the impacting ship. Notably, variations in collision positions (𝐻𝐻) and impact angles (𝛼𝛼) result in differences in collision forces and deformations at the bulbous bow structure. Therefore, careful consideration of parameters (𝐻𝐻) and (𝛼𝛼) is crucial to predict structural damage effectively. In addition, the pre-and post-collision motion behavior of the ship is also evaluated using a 6-degree-of-freedom (6 DOF) system.