The Bearing Impact Equal Load Carrying Capacity Design Of Butt Joint Of Ship-building 945 Steel Based On The Fracture Parameters K

Ships and submarines will be inevitably attacked by the explosives,such as torpedo during sailing.As for the vessels,such as high pressure vessel or super-high pressure vessel,the internal pressure will change continuously during operations.The destructive effects of changing pressure on welding parts and other weak positions should be particularly concerned.In this way,the impact resistance should be improved by designing the shapes of welded joints specially.In order to achieve this goal,a method was proposed in this work.When the welded joints and parent metals contain defects,the dynamic stress intensity factors KID was adopted as a parameter under impact loads.By changing the shape parameters of joints,these parameters should meet the relation K_w?t?/K_b?t?<K_ID^w?t?/K_ID^b?t? and the impact resistance of joints can be same as possible as the parent metal.In such a case the cracks would predominantly appear in the parent mentals rather than the welded joints,when they beared the same loads.This method introduced is meaningful for using in the industries.In order to achieve the impact resistance and equal load carrying capacity of butt joints,the finite element software MSC was used in this work on the basis of the impact principle of separate Hopkinson pressure bar?SHPB?,.The simulation of the impact process of the ship-building steel 945 was performed.Dynamic constitution relation samples were constructed by Johnson-Cook constitutive model and the initiation time was obtained by the compliance rate of change.After that the fracture toughness of standard specimen was obtained.In this paper,the inertia effect and the effects of strain rate were studied.Under the same impact velocity and the initiation time of standard specimen?the height of reinforcement h,the width of reinforcement m and the radius r of weld toe?,the simulation was performed.The results show that the different shape parameters can affect the fracture parameters of sample.Combined with the dynamic stress intensity factors theory,the correction factors equation of the joint shape factors under different shape parameters for the butt joints can be obtain through the shape parameters.So the butt joints under the bearing impact equal load carrying capacity conditions are designed successfully.In this paper,the different shape parameters of butt joints were simulated by using the theory of SHPB and the dynamic stress intensity factors KID as the criterion.Through the calculations and analysis,the correction factors equation of the joint shape factors under high speed impact was obtained,meeting the bearing impact equal load carrying capacity conditions.The bearing impact equal load carrying capacity was realized by optimizing the shape of the welded joint.This work is valuable in preventing the ships and submarines attacted by torpedo and other explosive...