Numerical Simulation Of Welded Plate Based On Equivalent Heat Source Parameter And Its Load Capacity

Welding technology has become the most common method of joining metal materials,increasing production efficiency and manufacturing levels in many fields.However,welding deformation and residual stress are inevitably produced during the welding process,which will reduce the load capacity of the welded structure.In this paper,based on the thermal-elastic-plastic method,the evolutions and mechanism of welding deformation and residual stress in butt-welded process were studied.Then,the influence of specific heat,heat input,elastic modulus,linear expansion coefficient,yield strength and welding sequence on mechanical field was studied.Finally,the effect of heat input and welding sequence on load capacity of the butt-welded plate was studied.Firstly,for the problems existing in the most commonly used thermal elastic-plastic finite element method in the welding process simulation,the concept of equivalent heat source parameter is proposed to consider the effect of phase transition,the complicated constitutive relationship near the weld and other factors on mechanics fields,and the inversion method of equivalent heat source parameter is presented.Then,the welding deformation and residual stress measured in the butt-welded plate experiment were used to invert the equivalent heat source parameter of the current materials,welded joint,welding conditions and environment.By comparing the numerical results with the experimental results,we can see that the two are in good agreement,which validates the proposed method and the butt-welded plate finite element model.Next,on the basis of butt-welded plate,the effect of increasing or decreasing by 20% based on the original specific heat,heat input,elastic modulus,linear expansion coefficient and yield strength on weld deformation and residual stress was investigated while keeping all other welding conditions and the finite element model unchanged.The calculation results showed that the specific heat,heat input,elastic modulus,linear expansion coefficient and yield strength do not affect the distribution of welding deformation and residual stress of the butt-welded plate,but only have a certain influence on the magnitude.Then,the temperature field and mechanical field of butt-welded plate under four welding sequences were simulated.By comparing the contour and results along the representative path under different welding sequences,the influence of welding sequence was discussed,and the reasonable welding sequence was obtained.The analysis results showed that the welding sequence has a great influence on the magnitude and distribution of temperature field and mechanical field,and the optimal welding sequence is WS4.Finally,based on the restart analysis and coupling techniques,the effect of heat input and welding sequence on the tensile load capacity of the butt-welded plate was studied with the consideration of welding deformation and residual stress.The results showed that the residual stress will significantly reduce the tensile load capacity of the butt-welded plate,and the tensile limit load decreases with the increase of heat input;the limit load of the butt-welded plate under WS1 is the smallest,and the difference in the limit load under the other welding sequence is negligible.