Structural Strength Analysis And Optimum Design Of Deep-sea Submersible

The 21st Century is the era of Deep Ocean exploring and developing. And the deep-sea submersible is a kind of equipment,which can perform ocean exploration, scientific survey and operational missions more effectively. The vehicle plays an important role in performing ocean-exploring tasks.The cylindrical pressure hull structure is guarantee for the run of the whole submersible. In this paper, calculation methods of structural strength of submersible cylindrical shell are researched, and the following aspects are included:1)In order to ensure the safety of the submersible, scale model experiment is necessary. It can be designed. to check the correction of theory calculation method.2)The submersible is subject to deep water pressure. And the structure must meet the requirement of strength, the stress is not allowed to beyond the permissible stress. The standards of strength of submersibles based on CCS rules ,GL's and ABS's are analyzed. The results are compared with that of the finite element method and the experiment.3) With the increase of diving depth, hydro pressure increases, and the pressure hull undergoes the process of material nonlinear buckling. When the whole structure buckles, it fails to bear the load continuously. In this paper the analysis of nonlinear buckling is done with ABAQUS.4)The opening can result in stress concentration and decrease the local strength. Yielding and bulking strength are assessed and the strengthening plan is given for the members that are not satisfied to the rules.5) The cylindrical pressure hull of the submersible is submitted to cyclic loads due to hydrostatic pressure during operation and fatigue failure may occur. Special at the part of large tension stress fatigue crack propagate easily. To insure safety of the submersible fatigue life analysis is critical. In the paper ,a methods is developed to calculate the fatigue lifetime of submersible pressure stucture,applyingε—N curve and linear elastic fracture mechanics. Through examples calculation, some conclusions are got.6) The paper aim at a type cylindrical hull structure with frame as research object, aim at the structure volume-weight ratio as optimize objective, we adopt parse method and FEM method to analyse all structure weight control technique by deeper submersibles structure weight optimize calculate under the term of keeping structure both intensity and stability.