Design and analysis on a model sphere made of maraging steel to verify the applicability of the current design code

摘要

A bolt-connected deep-sea manned cabin made of maraging steel 18Ni(250) with an inner diameter of 2.1 m is under development, which will be applied to full ocean depth. As a promising guideline, the design formula by CCS is considered to be applied. However, the formula is originally derived based on titanium alloys with a strength level of 800 MPa. Whether it can be used for manned cabin of maraging steel in case of no change in the design coefficients should be checked. A model sphere will be designed and tested to collapse under uniform external pressure inside a high-pressure chamber to check the effectiveness and practicability of the design formula and the manufacture technology. Results of ultimate strength predicted or calculated by the design formula and direct finite element methods are compared with the experimentally obtained value. The influence of simplification on material properties and initial geometry imperfection is considered and discussed.