ABSTRACT
The manned sphere of deep sea manned submersibles during their service life will experience periods of both fluctuating and steady stresses, as shown in Fig. 1(a). Then fatigue property of the structure has received attention due to such cyclic loading. Furthermore, the fatigue life prediction method based on crack growth rate theory is currently more promising in industry as inside defects of the material is unavoidable. Currently, fatigue strength assessment of the manned sphere of deep sea submersibles has become more important in the process due to the increase in the requirement of the safety which is an extremely complex
1 INTRODUCTION
Deep sea manned submersible technology is currently an important part of oceanic advanced technologies. The pressure hull is the pivotal component of submersibles, which provides a safe living space for pilots and scientists, and should be designed to have enough strength and be as light as possible (e.g. ABS 2010, Pan & Cui 2010). The pressure hull consists of thick spherical modules welded together with several large openings. The property of the materials and jointing positions must receive significant attention during material selection and structure design for safety.
