5059 aluminum alloy has become the preferred choice for the ship structure due to its excellent mechanical properties and corrosion resistance. However, the current code lacks the S-N fatigue curve of the 5059 aluminum alloy, imposing difficulties on the fatigue evaluation of the 5059 aluminum alloy ship structure. The 5059 aluminum alloy and a typical marine welded joint are designed to carry out the fatigue tests at the room temperature and the low temperature (-35℃). The corresponding fatigue S-N curve is fitted by the least square method based on the test data. A finite element model of the specimen for fatigue test is established, and the stress obtained by the finite element analysis is extrapolated to obtain the hot spot stress. The fatigue life of the fatigue specimen is predicted by using the fitted S-N curve and compared with the result from the fatigue test. The results show that the proposed S-N curve of the 5059 aluminum alloy material and the welded joint can be used to predict the fatigue life of the ship structure under the low temperature environment.

The maximum ship bridge impact force and its relationship with influencing factors are of great significance for the reduction of the harm to the personal security and safety of their belongings caused by ship bridge collision. The finite element model of the ship bridge collision has been established by using ANSYS/LS-DYNA to calculate the ship bridge impact force under different impact velocities and impact angles. And the calculated results are compared with those from the rules of various countries. A model for the prediction of the maximum ship bridge impact force is then established under three training parameters of the maximum impact force value, impact angle and impact velocity by using the Back Propagation (BP) neural network technology together with the simulation data. Finally, an empirical formula of the relationship between the maximum impact force and the impact velocity and impact angle is fitted by analyzing the scatter diagram of the impact velocity and the impact angle. And the results of the empirical formula are compared with the finite element simulation results and the neural network prediction results to validate the accuracy of the empirical formula. It provides a rapid method for evaluating whether the ship bridge collision will have catastrophic consequences.

Floating production storage and offloading (FPSO) unit is an offshore oil and gas processing unit that integrates the ship hull system, topside oil and gas processing system, mooring system and export system. The system of FPSO is very complex and easy to cause serious accidents in case of oil and gas leakage. The firefighting system is the important subsystem of FPSO ship system and the important guarantee for personnel and production. The fire situation in the fire compartment has been analyzed to configure the reasonable extinguishing methods aiming at the rationality of the firefighting system design and the equipment selection for the internal turret moored FPSO. A calculation method for the firefighting system of the internal turret FPSO is then proposed based on the relevant rules and regulations. It can improve the safety and reliability of the firefighting system design and ensure the safety of the FPSO production and the crew safety. This firefighting system calculation method is critical to the design of the firefighting system and the equipment selection. It can provide reference for the design of the FPSO firefighting system.