Numerical Simulation And Experimental Research On Welding Residual Stress Of Thick Plate For Steel Bridge

At present,welding is widely used in the connection of the bridge steel structures made in factories,and bolting-welding joint and fully welding joint have been gradually applied to the on-site assembly of steel bridge components.Welding residual stress is a prominent factor which has an adverse effect on mechanical properties and service life of steel bridge components.Compared with thin plates,the thickness of plates used in the steel bridge is much larger which means the welding residual stress distribution is more complex,so the residual stress in thickness direction and the change of residual stress along the thickness direction should not be ignored.Aiming at solving this problem,welding residual stress of a 45mm-thick Q345qD butt welding steel plate has been studied with the methods of numerical simulation and experimental measurement.The main works of this thesis are as follows:(1)Firstly,the development of welded steel bridges in China and the application of thick plate in steel bridges are introduced,and the fatigue and lamellar tearing are proved to be closely related to the welding residual stress.Then the definition,formation,classification of welding residual stress and its influence on structures are summarized.At last,the research progress of basic theories,numerical simulations and measurements of welding residual stress are summarized in detail.(2)Then,the application of finite element method in welding temperature field and stress field analysis is discussed systematically,and some basic forms of heat transfer,welding temperature field finite element equations,thermal elastoplastic analysis method and related fundamental theories are introduced.(3)Based on ANS YS,the three-dimensional temperature field and stress field of the thick plate are analyzed.With the help of pretreatment software HYPERMESH,the finite element model of the specimen is built.The realization process of the numerical simulation of multi-pass welding is described in detail.The distribution of temperature field and welding residual stress are obtained by finite element method.(4)The residual stresses in the surface and inside of the thick plate are measured by blind-hole method and layer-removal method respectively.By comparing with the measured results,the rationality of the finite element calculation results is verified.Based on the calculation results,the welding residual stress distribution simplified diagrams of this particular thick plate are proposed,which can be used as reference for the related research and calculation in bridge engineering.Through the results of this study,the welding residual stress distribution of steel thick plate could be learned preliminarily,which is beneficial to the further study of the distribution,control and elimination of welding residual stress in typical components or structures used in steel bridges.