During the thermal launch operation of offshore launch platforms/ships, they will be subjected to the combined effects of rocket impact, wind, waves, and currents. Due to different arrangements of mooring systems, the motion response and mooring stress state of offshore launch platforms/ships are affected, which in turn affects the safety of the platform/ship-arrow. Therefore, this article explores the mooring arrangement of offshore launch ships under the coupling of multiple factors, including the arrangement of mooring point positions and changes in mooring line lengths, and their effects on the motion response and mooring stress state of offshore launch ships. Research has found that placing the mooring point below the waterline of the launch vessel and appropriately increasing the length of the mooring line will be more conducive to the conduct of offshore launch operations, providing technical references for the future layout of offshore launch vessel mooring systems.

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.

The significant design redundancy in the offshore wind turbine infrastructure results in high construction costs for offshore wind turbines. The design of the jacket offshore wind turbine should be optimized to improve the economic benefits of the structure. Firstly, the environmental load of the offshore wind turbine is simulated based on the data from the sea trial to obtain the time history of the environmental load of the offshore wind turbine. Secondly, the strength of the flat box girder type four-pile jacket offshore wind turbine infrastructure is checked by using the finite element method, indicating that the structure can be lightweight. Finally, with the target response of the maximum average stress, maximum displacement and mass of the structure, the contribution and main effect relationship of the structure scantlings to the target response of the structure are obtained by the optimization method combing the design of experiments (DOE) with the particle swarm optimization (PSO) algorithm, and the optimized structure scantlings are determined. The structural optimization of the offshore wind turbine infrastructure can reduce the construction costs while ensuring safety. It can provide parameter references for subsequent design and construction of the offshore wind turbine infrastructure.

The offshore launch platform considering the thermal launch of a rocket at sea has been studied. The Realizable k-ε turbulence model and the three-dimensional potential flow theory are used to study the time-domain motion response of the platform under the impact load of the rocket wake and the combined loads of the wind, wave and current. The heave, roll, pitch and yaw of the launch platform during offshore launching under two sea states are compared and analyzed. The analysis and calculation show that one sea state is more beneficial to the two-way safety of the rocket and the launch platform than the other, and the launch platform should avoid offshore thermal launching in beam waves. In addition, a simple calculation method of the wake impact under offshore launch condition is proposed to obtain the pressure time history of the gas wake impact for single Laval tube, providing theoretical and engineering foundation for the subsequent study of the structure and motion performance of the launch platform.