Numerical Simulation Of Welding Deformation For Tower Crane Pedestal

The marine tower crane pedestal has high requirements in terms of reliability,wind resistance,corrosion resistance and maintainability because of its external environment and the particularity of operation process.Therefore,the welding deformation of tower crane pedestal must be strictly controlled.However,the size of pedestal structure is very large,and it is very difficult to determine the optimal welding sequence by experimental method.Therefore,it is important to predict the welding deformation accurately by numerical analysis and to determine the optimal welding process.In this paper,finite element method software ABAQUS is used to simulate the welding process of large offshore crane pedestal.First of all,this paper presents an optimized-segment-heat-source,based on the traditional length-segment heat source,for numerical simulation of large-scale structural parts welding process,which is characterized by large number of nodes and low computational efficiency.The experimental results show that the optimized-segment-heat-source greatly improves the calculation accuracy under the condition of ensuring the calculation efficiency.Secondly,the proportion model of tower crane pedestal is established.The welding induced deformation and residual stress of priming weld seam were simulated and analyzed by using the optimized-segment-heat-source model.The results show that the axial shrinkage deformation is the main cause of welding deformation.Welding deformation of multi-heat source welding sequence is the smallest in single welding sequence,intermittent welding,and multi-heat symmetrical welding.The deformation of multi-heat source welding sequence is decreased by 14.7% and 14.6% compared with that of the other two model respectively,and the maximum axial shrinkage deformation is decreased by 14.6% and 7.9% respectively.The large deformation distribution area of Model2 and Model3 is smaller.In term of the perspective of control deformation,the symmetry welding sequence of multiple heat sources is the optimal process.Finally,a 1/4 cylinder model of the tower crane foundation was established,and the trend of welding deformation increment of the second and the third layers was analyzed.It was found that the restraint effect of bottom weld seam on welding deformation gradually increased with the number of filling bead increased,and the increment of the axial deformation and the radial deformation of each additional weld bead decreases.Therefore,in order to reduce the welding deformation of the whole cylinder,it is important to control welding deformation of the priming weld seam.And the welding process of filling bead remolded the welding residual stress after the welding of priming weld seam.The higher welding residual stress in Model3 caused by the multi-heat source symmetry welding sequence in the seam welding process can be changed.