| Welding distortion of the leg rack on marine petroleum platform will make racks loss the accuracy of mesh and residual stress can led to stress concentration. This paper simulated the welding residual stress and the welding deformation of leg racks on marine petroleum platform by thermo-elastoplastic finite element method.This article discussed systematically the theory of thermo-elastoplastic finite element method in welding process and introduce the method and procedure of simulation .Then simulate the welding process of flat butt welding with a V groove. In the calculation of temperature fields, it is used internal heat generation as the heat source and SOLID90 element for non-uniform mesh. In the calculation of stress and distortion use diffient reference temperature between base metal and weld matel. In two calculations simulate the process of the weld cell filling by the"element birth and death". Finally, simulation results were compared with experimental results. Both of them agree with dual stress distribution and deformation from the results of simulation match theoretical results.To sum up, the thermo-elastoplastic finite element method in welding process is right in the paper.And then with the same method, this article simulate welding process of the leg rack on marine petroleum platform. If four weld seam of the rack welding at the same time, the load and the structure of the rack is symmetrical so as to establish 1/4 model of the rack to simulate instead of the whole model. This greatly reduces the number of elements and the calculation.In order to know how welding sequence affect welding stress and strain, this paper simulate the welding process of the virtual structure under different welding sequence. that is reduced to 1/4 of the original dimensions of rack in proportion And through analysis of different simulation results showed that rack do not exist welding deformation and at the root of tooth equivalent stress is symmetrical. So,this welding sequence is better. |
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