Research On Structural Strength Analysis Method Of Grid Type Cage Cage

The deep-see cage always working in the poor environment,so the deep-sea cage is required to have high structural strength.The special structural form of grid cage brings difficulties to load calculation and structural strength evaluation,so it is of great significance to study the structural strength evaluation method of grid cage in deep sea.The conventional strength analysis of cage floating structure mainly adopts the quasi-static analysis method or the structural dynamic analysis method considering the ocean current force,but the research on the structural dynamic response of cage under the combined action of wave and current is less.At the same time,as a flexible small-scale component,the coupling effect between elastic deformation and flow field is obvious,so it is necessary to consider the influence of fluid structure coupling effect on structural response.Based on Morison equation,this paper calculates the load response of the floating structure of the net cage.The finite element analysis method is used to analyze the structural response of the floating structure of the net cage.The analysis methods include quasi-static analysis method,dynamic analysis method without considering the influence of fluid structure coupling and dynamic analysis method with considering the influence of fluid structure coupling.The main contents of this paper are as follows(1)Static strength analysis of floating frame structure of deep sea cage.Based on Morison equation,a program for calculating wave load is developed,and the design load is determined according to the design wave method.The quasi-static structural response of the floating frame structure of the net cage under different working conditions is analyzed,and the calculated results are compared with the allowable stress values in the code.(2)Dynamic strength analysis of floating structure of deep sea cage without considering the effect of fluid structure interaction.By means of user subroutine,the time history load response obtained by Morrison load calculation program is applied to the finite element model,and the stress nephogram of the dynamic response of the lower floating frame structure at different times is extracted to analyze the location of the maximum stress and the stress variation law of the floating frame structure at different times.(3)Dynamic strength analysis of deep sea cage floating structure considering fluid structure coupling effect.The iteration model of finite element model and hydrodynamic model is established by writing user subroutine.After a finite number of iterations,the dynamic response analysis of the cage floating frame structure considering the effect of fluid structure coupling is realized,and the stress nephogram of the structure dynamic response at different times is extracted.The results are compared with those without considering the effect of fluid structure coupling,and the stress variation law is summarized.