| The marine resources development is imminent with the shortage of land resources,meanwhile,with the human material life level enhancement,the pursuit of a better life has become a mainstream of social development.Offshore aquaculture can’t meet the needs of human beings with the demand of high quality protein increased year by year and the excessive development of offshore fishery resources and environmental degradation problems,it is the inevitable trend which the offshore developed to the deep sea.In this background,taking the deep-sea net cage platform developed by the company as an example,the strength and fatigue mechanical properties of the new deep sea cage platform are studied by means of random fatigue analysis.The classification of net box structure and the main design characteristics of net box structure have been introduced,and the operation mode and design condition of deep sea cage has been checked according to the inherent characteristics of net box structure.The input information of the environmental load of the net box structure is also introduced.Finally,the consideration methods of netting effect and netting effect in design engineering structure and the influencing factors of netting load are introduced.The overall strength of the whole structure of the deep sea cage platform is checked under the condition of storm self-survival.Based on the actual structure,SACS software is used to simulate the main structure,and the appropriate method is used to simulate the net coat.The main load forms of the cage platform under the condition of storm self-survival are determined.The bearing capacity of the main structure under the self-survival condition and the impact shear capacity of the joints are checked,and the load-bearing capacity of the main structure and the impact shear capacity of the joints under the self-survival condition are checked.The strength of key joints is checked by means of local finite element model and SACS load input.The basic design of the deep water intelligent seated net box with circular tube section truss is verified,which accords with the basic structure requirement of API code.The results show that the overall strength of the device is enough to meet the prescribed design conditions.The direct algorithm based on spectrum analysis of fatigue strength evaluation of deep sea cages platform.Searching all the nodes on the entire platform,choose the typical nodes in where play an important role air tightness,water tightness and overall strength.Calculate the fatigue life with normal stress method.While the response of the deep-sea cage platform to the wave load is not the same as that of the deep-sea cage platform due to its scale.Different locations need to be analyzed separately.The analysis method of pipe joint stress concentration factor is introduced,and the definition and value standard of nominal stress hot spot stress of pipe joint are summarized.The fatigue damage mechanism of pipe joint and the fatigue analysis method of pipe joint are introduced.On the basis of this,the stress concentration factors of different types of pipe joints are studied,and the conventional X-shape is mainly distinguished.The stress concentration factors of Y-shaped and K-shaped joints with transverse brace added in the normal node form and in the main pipe are different.Through the comparison,it is found that the fatigue life of the joint can be improved effectively by increasing the support structure of the main pipe in the marine ranch structure which is dominated by out-of-plane bending load. |
