Influential factors to be considered for a tentative long-term service life assessment method for deep-sea manned cabins

Abstract

[Objectives] Deep sea exploration using manned submersibles is of increasing interest to human beings,but breakthroughs are required in many aspects,especially in the safety and reliability of manned cabins.[Methods] To this end, factors affecting the safety and reliability of manned submersibles are studied in this paper using experimental and numerical methods,including the effects of inherent void defects on material ductility,the effects of prior cyclic history on the tensile properties of materials,and the effects of dwell time on the cyclic properties and crack propagation performance of materials.[Results] The results show that the wide distribution of voids will greatly decrease the ultimate strength of the structure through its effect on ductility,and the existence of the dwell time should not be neglected when evaluating the residual strength of the structure based on the S-N curve and crack growth approaches. Such mechanical properties as the elastic modulus,strength and ductility of the material showed a slight decrease as more prior cycles were applied before the tensile experiment.[Conclusions] The results can provide references for evaluating the long-term service life of deep-sea manned cabins.

Keywords

• submersibles
• deep-sea manned cabins
• internal defect
• dwell time
• strength attenuation
• finite element method