Study On Shock Environment And Ultimate Bearing Capacity Of Cylindrical Shell Subjected To Underwater Explosion

In recent years,marine resources and maritime territorial disputes are increasingly frequent,and various anti-ship weapon guidance technology is increasingly mature,the possibility of submarine structure attacked by large equivalent underwater weapons is growing,so the anti-strike capability of submarine suffered attacks from underwater explosion and ultimate load in different water depth are worthy of our concern.On the basis of characteristics of the explosion in underwater,this paper studied the load suffered near field underwater explosion,dynamic response,shock environment and damage characteristics though analyzing a number of circular cylindrical shell structure model.It provided important reference value for improving the submarine.Firstly,the shock environment of submarine affected the personnel safety and equipment onboard directly in wartime,the bad shock environment damaged the submarine,so the shock environment of submarine is an important safeguard.In this paper,the shock environment of cylindrical shell structure subjected to underwater explosion is well studied by using a cylindrical shell to simulate submarine cabin.Though integrated modeling of cylindrical shell,inspection points are set in short cabin 1,long cabin 2 and working platform.Using structural-acoustic coupling method in ABAQUS finite element software to calculate the point value of shock spectrum under the condition of the shock factor is 1.The results showed that the shock dynamic response of long cabin is more intense compared to short cabin,the shock environmental is closely related with the installation form,shock on the end is worse than that on the middle part.These can provide a reference for the design of shock resistance.Then,it is considered that the submarine is completely in the underwater combat environment,the hydrostatic pressure which is considered as the radial loading mode has a great influence on the structural strength.Therefore,the paper mainly studies the how the plastic damage of the structure of the reinforced cylindrical shell subjected to underwater explosion effects the ultimate bearing capacity of the shell.Firstly,the finite element software ABAQUS was used to analyze the linear buckling of the original complete model and the cylindrical shell with openings.The results of the linear buckling analysis were added to the model as the initial defect,and then the nonlinear buckling analysis was carried out.Among them,for the opening cylindrical shell structure,according the comparison,it is found that the larger the hole size,the structure of the ultimate bearing capacity is weaker,and for the RIKS method there is a threshold,the recommended aperture does not exceed the critical value.Finally,the influence of the impact damage caused by different impact factors on the ultimate bearing capacity of the cylindrical shell is explored.The plastic damage caused by the underwater explosion shock wave is used as the initial defect of the structure in the nonlinear buckling analysis.According the comparison,t is found that the greater the impact factor is,the greater the impact damage caused by the underwater explosion shock wave to the structure is,the greater the plastic deformation of the structure is,resulting in the worse the ultimate load is.And the cylindrical shell under underwater explosion is compared with the original model without impact.It is found that the ultimate load of the structure is obviously reduced,which shows that the underwater explosion has great influence on the ultimate bearing capacity of the structure.Furthermore,the characteristic of cylindrical shell structure is simple,differences between models are nothing more than the length,the diameter and stiffener size.In the analysis about the anti-shock of cylindrical shell,the feasibility about using local model instead of the global model has been taken into account.The effectiveness of this kind of replacement was explored by setting three different length of the cylindrical shell model,and analyzing errors which get from the structural response under the same position with the same dose and five different distance.When the error is less than a certain value,the local model can replace the global model.