Numerical Simulation Of Welding Distortion And Residual Stress In Deck Grillage

Welding is a crucial process in ship manufacturing,and it has significant effects on the quality and performance of vessels.Welding deformation and residual stress are commonly detected during welding,which can be controlled conveniently and economically by applying numerical simulation to investigating them.Thermal elastic-plastic finite element method(TEP FEM)is widely used for its high accuracy and flexible applicability.However,time-consuming calculation and poor convergence confine its use in large scale welding structure of vessels.In order to increase the efficiency of TEP analysis and fulfill research on large scale structures,this paper applies temperature field mapping technique,shell/solid model and segmented moving heat source based on ABAQUS code,the main contents are as follow:(1)A comprehensive review on the research methods and current situation about welding domestic and overseas.Firstly,inherent strain method and TEP FE method and their application in large scale structures are introduced.Then,element and heat source adaptive mesh technique,and parallel computing in TEP are explained.Meanwhile,the theories of temperature and stress analysis and shell element with section integration are discussed.(2)Dividing ship structure into several static substructures based on its symmetry and repeatability,temperature field mapping technique is proposed.Overall temperature results can be obtained efficiently via PYTHON by mirroring and translating temperature field of the calculated results implemented by TEP FEM.The temperature mapping technique and shell/solid model are applied to a large ship stiffened panel to verify the efficiency and accuracy of such method.Meanwhile,welding characteristic of the structure is discussed.(3)A large ship stiffened panel is selected to elaborate the influence of welding procedure of stiffeners' both sides on welding distortion and residual stress.An optimized welding procedure is proposed to improve welding distortion and residual stress.(4)A segmented moving heat source combined with temperature mapping technique and shell/solid model is employed in TEP analysis of a large deck grillage.The contribution to overall and local distortion of longitudinal and transverse stiffeners is discussed.The effects of welding sequences of longitudinal and transverse stiffeners to welding distortion and residual stress are compared.