Numerical Simulation And Control Research On Plate Unit Welding Deformation

Steel box girder structure is used widely in large cable-stayed bridge and various elevated bridge because of its own quality light, simple structure, the characteristics of large carrying capacity. Orthotropic plate unit is the main component of steel box girder, it consists of steel plate(top,bottom),U-rib and diaphragm plate. The diaphragm plate generally is assembled and welded while steel box girder bridge deck manufacturing or installing on-site, and the plate unit that welded U-rib is assembled in the production workshop.At present the common plate unit structure includes three to five U-ribs, while welding the U-ribs, the plate unit mainly has four forms of welding deformation, they are longitudinal contraction deformation,transverse contraction deformation,the longitudinal surface bending deformation and angular deformation. The welding deformations generated in the process of manufacturing the plate have a negative impact on the performance,the dimension preciseness and stability, and they also cause the unfavorable influence at steel box girder assembly production, Because of the large numbers and great workload when building bridge, if not value, they will cause great loss.Based on the previous research, with large common software ANSYS, this paper researches how to realize the 3D dynamic simulation of welding temperature fields,stress field and welding deformation, then uses the research result to simulate the welding process of the typical top plate unit with U-ribs. In the process of numerical simulated calculating, with the thermal-structure coupling function of ANSYS software and indirect coupling, welding temperature field is calculated firstly and the results are saved in file type of *.rth, and then temperature results recovered from the former files are added on the structure models as load to simulate the stress and strain field. By simulation of temperature field and stress field in the indirect method, the temperature distributions at different times, residual and strain distribution is gotten using the birth-death element method, then the analysis of the welding deformation regulations and characteristics can be gotten, they can give the guidance of optimizing the welding procedure and rectifying the welding deformation.The paper mainly researches on the following contents:1.Establishing three dimensions finite element model of welding process analyzing welding temperature field and welding stress temperature, obtaining welding residual stress's distributing rule.2. Summarizing the types and influencing factors of the plate unit welding deformation and analyzing the causes, on the basis of them, the paper compares the numerical simulation results with the actual value.3.According to analyze the characteristics, the paper comes up with control measures from three aspects including pre-welding, welding and post- welding.