Research on the quasi-static collapse and instantaneous implosion of the deep-sea spherical pressure hull

Manned submersibles are an important deep-sea survey and operation tool. As the most important component of manned submersible, the spherical pressure hull provides a safe living space for pilots and scientists under high pressure. Therefore, research on the collapse load, collapse mode and impact of implosion on nearby structures is essential. In this paper, a tensile test of a titanium alloy specimen is conducted to determine the value of fracture strain in finite element modelling. Then, transient dynamic and quasi-static simulations are performed based on the scale model experimental process of a deep-sea pressure hull with a designed service depth of 4500 m. The first-order buckling mode is introduced as the structural geometric imperfection during calculation, and quasi-static step loading is applied to the surface of the spherical pressure hull. The results show that the collapse load and mode by the simulation and experimental results are consistent with each other, and the instantaneous impact is studied with the collapse pressure set as the initial pressure. The study of the implosion shock wave will provide a reference for protective measures during the experimental process in a pressure chamber and for underwater operation safety assessments of manned submersibles.