Numerical Simulation Of Welding Buckling Deformation In Thin Plates With Considering Initial Residual Stress Influences

Welding is the main connection method for the manufacture of large structures such as ships,and has occupied a very important position in the field of material processing in recent years.Although welding can permanently connect materials,in the welding process,due to the nonlinear nature of the material properties and the inconsistent temperature changes,the stress distribution inside the welded structure and the deformation of the outer surface are caused.As a result,the mechanical properties of the material are reduced and the service life is shortened.And in the actual project,the welding part will go through a series of hot processing and mechanical processing before welding.In this way,there will be some initial residual stress distribution in the weldment before welding.Based on the above research background,in order to study the effect of initial residual stress on the distribution of welding residual stress and its numerical value,a finite element model of hot rolling forming and welding manufacturing was established in this paper,and the residual internal stress generated after hot rolling of thin sheet was explored.Impact on the welding process.In the study,the residual stress caused by rolling was inherited from the welding prediction analysis,and a three-dimensional thermo-elastic-plastic finite element calculation program was developed.Based on the direct thermal coupling method,the Q235 steel butt welding with a plate thickness of 5mm was taken as an example.The prediction of the welding residual stress and deformation was numerically simulated,taking into account the characteristics of the physical and mechanical properties of the metal material as a function of temperature.The distribution law of welding residual stress is obtained: During the welding process,the thermal stress of the metal around the weld is in the state of compressive stress and gradually increases.In the cooling process,the nature of the internal stress changes,that is,the compressive stress is gradually reduced.Later it turns into tensile stress.After cooling to room temperature,the residual stress is symmetrically distributed along the direction perpendicular to the weld.Welds and heat-affected zones exhibit tensile residual stress distribution,and the base metal zone exhibits compressive residual stress.Along the direction of the weld,the residual stress is also symmetrically distributed: the metal in the middle of the weld is stressed and the metal at both ends of the weld is pulled.After analyzing the calculation results of the two schemes comparing the thinplate with the initial residual stress,it is found that the residual stress distribution calculated by the two schemes is similar in the direction along the weld and in the direction perpendicular to the weld,but it is numerically similar.have difference.The theory of the stability of the thin plate structure is introduced.The buckling deformation of the welding is calculated using the eigenvalue buckling analysis method.The first four buckling eigenvalues and the modal deformation map are obtained.Through analysis,it can be concluded that the critical buckling load of the welded structural member can be increased by selecting a reasonable size of the panel or applying specific boundary constraints,thereby avoiding the occurrence of destabilizing deformation during the welding process.Finally,the basis for judging whether the unstable deformation occurs during welding is obtained.