Development Of High Efficiency And High Precision Calculation Method To Predict Welding Deformation Of Large Structures

Fusion welding is an important metal connection technology,which is widely used in industrial manufacturing fields such as ships,aerospace,automobiles and so on.During the welding process,due to the rapid heating and cooling process of the heat source,welding deformation is inevitably generated in the welded joints or welded structures.Welding deformation of welded structures not only reduces manufacturing precision,assembly precision and bearing capacity,but also increases production cost and time.After nearly fifty years of development,the welding numerical simulation method has gradually become a powerful tool to predict and control welding deformation.Although the thermal-elastic-plastic finite element method can accurately calculate the welding deformation,it is still difficult to directly use this method to predict the welding deformation of large structures in practical engineering at this stage due to the scale and calculation time of the model.Therefore,it is of great engineering significance to develop an efficient and high-precision calculation method to predict the welding deformation of large structures.Based on the finite element software ABAQUS,a thermal-elastic-plastic finite element method was developed to simulate welding deformation of welded joints,which can simultaneously consider material nonlinearity,geometric nonlinearity and contact nonlinearity.Besides,an elastic finite element calculation method based on the inherent strain theory was developed to simulate welding deformation of large structures.Firstly,the influence of weld length on the inherent deformation of Q235 steel sheet surfacing joints was studied by combining experimental methods with numerical simulation.Based on the comparison between the experimental results and the numerical simulation results,the reliability of the thermal-elastic-plastic finite element method and the inherent strain method was verified.Then,the influence of constraint conditions and plate thickness on the inherent deformation of Q345 steel T-joints was investigated experimentally and stimulatingly.Meanwhile,the influence of free,structural and external constraint conditions on the calculation accuracy of inherent deformation of the simple stiffened plate and panel-bone structure were studied by the elastic finite element method.Finally,the welding deformation of International Thermo-Nuclear Experimental Reactor(ITER)side correction coils under the conditions of laser welding and Tungsten Inert Gas cover welding was predicted by the thermal-elastic-plastic finite element method and the elastic finite element method.Based on the numerical simulation results,the influence of external constraint conditions on the welding deformation of ITER side correction coils was discussed.The results of the study are shown as follows: 1)for the thin plate surfacing joints in this study,with the increase of weld length,the transverse shrinkage,angular deformation and longitudinal bending deformation are increased when the geometric size of the specimen is constant.2)For the T-joints,with the increase of constraint strength,the angular deformation and transverse shrinkage decrease,while Tendon Force changes slightly.3)Compared with the free and external constraint conditions,the inherent strain of the T-joint under the structural constraint condition can be more accurate to calculate the welding deformation of simple stiffened plate by the elastic finite element method.Moreover,the computational efficiency can be increased by 20000 times compared with the thermal-elastic-plastic method.4)In the panel-bone structure,the value of out-of-plane deformation calculated by the inherent strain of T-joint under external constraint condition is the smallest,while the value is the largest under free condition.If it is necessary to accurately predict the welding deformation of the panel-bone structure,it is more reasonable to adopt the inherent strain under structural constraint condition.5)The welding deformation of the ITER side correction coil is predicted by combining the thermal-elastic-plastic method with the inherent strain method.The numerical simulation results show that the existing welding process conditions of laser welding and Tungsten Inert Gas cover welding can meet the manufacturing accuracy requirements of the side correction coil.