Numerical Simulation Of Weld Shaping And Stress Field Of Rotating Arc Narrow Gap Welding

Rotating arc narrow gap MAG welding is a high quality and efficient welding method for medium and heavy plate.The key is to get a stable and adequate sidewall penetration.Traditionally,understanding and improving the welding process by accumulating process test data requires a significant cost.In addition,numerical simulation has become a powerful means of analysis with the rapid development of computer technology and finite element theory.Therefore,the numerical simulation technique is used to study the dynamic change process of temperature,stress and flow field in rotating arc narrow gap welding,which has important significance in academic theory and engineering application.In this paper,the ABAQUS software is used to establish the relevant physical model based on the characteristics of rotating arc welding firstly.The arc overall heat source is equivalented and optimized and the three-dimensional temperature field is calculated.The simulation results are compared with the experimental results in the aspects of thermal cycling curve,sidewall penetration and transient temperature field to complete the thermal field calculation.Then,on the basis of thermal field,the stress field of the multi-layer single track welding is calculated by using thermo-mechanical coupling.The simulation results are compared with the actual welding results to summarize the distribution of stress and strain.After that,add different binding conditions in the model to simulate the impact of the plate or fixture on the redidual stress,and change the welding direction in the process of multi-layer welding to further improve the understanding of the stress and stain distribution,and the stress field calculation is completed.Finally,the influence of the driving force such as buoyancy,electromagnetic force and surface tension on the forming process of the weld is studied by using Fluent software to complete the flow field calculation.The thermal field results show that the sidewall penetration and bottom penetration are consistent with the actual results,and the calculation accuracy and efficiency of the optimized cake equivalent heat source are greatly improved in the numerical simulation of the rotating arc welding.The stress field results show that there is a small residual transverse compressive stress and a large longitudinal tensile stress in the weld zone.The transverse stress after the weld zone is rapidly transformed into tensile stress and gradually decreases toward zero,and the longitudinal stress decreases rapidly to compressive stress.The multi-layer welding under certain confinement conditions can control the deformation after welding and change the stress distribution,and changing the welding direction in the multi-layer welding can reduce the peak stress and make the stress distribution more gentle and symmetry.The results of the flow field show the influence of the driving force on the heat transfer and flow characteristics.The main factor that determine the internal flow field and forming of the molten pool is surface tension,and the buoyancy and electromagnetic force will affect the size of the molten pool.The convective motion caused by the driving force reduces the peak temperature.In this paper,the numerical simulation of the rotating arc narrow gap MAG welding is carried out,and the changes and distribution of thermal,stress and molten pool flow in the welding process are displayed intuitively and dynamically,and the regularity of the molten pool forming and stress distribution are further clarified,which has great significance in exploring the physical essence of the welding process and researching the related welding technology.