Fatigue Life Analysis And Safety Assessment Of Manned Submersible

With the consumption of the earth’s resources,the ocean has become the most strategic space for development.The development of marine science and technology benefits from manned submersibles and other marine deep submersibles.Therefore,it is of great practical significance to study the fatigue reliability and establish the safety assessment methods.This paper takes the manned submersibles as the research object,and studies fatigue reliability,fatigue life prediction and safety assessment methods of the manned submersibles.The main research contents include:Based on finite element analysis and fatigue prediction model,the fatigue reliability of manned submersible is studied.On the basis of finite element analysis software,the stress and strain of three different manned cabin structures are analyzed.The results show that the metal connecting rods and round ribs are helpful to improve reliability.The fatigue prediction model,which based on crack propagation,is used to analyze the fatigue reliability.The effects of crack initial value,material constant,stress intensity factor and other parameters on the crack-life curve are explored.Based on crack propagation and fatigue reliability,the life prediction of manned submersible is studied.Load spectrum which established based on the fitting Gumbel distribution function,is divided by using the non-linear virtual interval division technique.By establishing the relationship between crack length and reliability,and using the non-linear virtual interval division method of load spectrum,the fatigue life prediction model of the manned cabin structure is established.The results show that when the initial value of interval division is greater than 80,the fatigue life tends to a stable value.Based on expert system and safety evaluation index system,the safety evaluation of manned submersible is studied.The evaluation index system of manned submersibles is established by comprehensive fuzzy evaluation and fault tree analysis method.The importance of the index structure is used as the evaluation basis,and the corresponding weights of the evaluation index system are solved to form a method of safety assessment.The proposed safety assessment method is applied to the safety evaluation of the manned submersible,and it is confirmed the safety of manned cabin.