Study Of Welding Buckling Distortion And Its Influence Factors Of A Multiply Stiffened Thin-Plate Structure Under Single-Side Welds

Stiffened thin-plate panels,which can save material and reduce weight of the structure on the premise of guaranteeing reliability and durability,are widely used in ship manufacturing.Welding of the thin-plate structure easily induces buckling distortion.It will not only reduce the stiffness,stability and fatigue strength of structure,but also affect the following utilization and welding.As a numerical simulation method,thermal elastic-plastic finite element method(TEP FEM)can be used to predict the welding deformation and residual stress effectively,which can help choose reasonable welding technique before welding and improve welding quality.In this dissertation,welding simulation of a typical ship multiply stiffened thin-plate structure under single-side welds is carried out in ABAQUS/standard software by applying shell/solid model to enhance calculation efficiency.Influence of welding sequences,weld feet position,gravity,heat input and initial deflection of the base plate on welding deformation and residual stress is discussed,the main contents are as follow:(1)A comprehensive review on the current situation and progress about welding simulation,prediction of welding deformation and residual stress of thin-plate structure and welding buckling distortion.Introducing basic theory of sequential TEP FEM,including typical heat transfer theory,temperature field analysis theory and machanics field analysis theory.(2)Welding deformation and residual stress of the stiffened thin-plate structure under three different welding sequences and two weld feet positions is calculated to investigate the influence of welding sequences,weld feet position and gravity on welding deformation and residual stress.The results show that welding sequences and weld feet position have certain influence on welding deformation,but distribution of residual stress is not affected by these two factors significantly.Gravity has little effect on welding out-of-plane distortion.(3)Welding simulation of the structure under six different heat input conditions is carried out to analyze the influence of heat input on welding deformation and residual stress,especially on buckling distortion.The results illustrate that increasing heat input has significant influence on welding deformation,which will enlarge out-of-plane distortion and shrinkage distortion and induce local and global buckling on the structure.The residual compressive stress in the base plate increases with the increment of heat input,which is the primary reason of buckling distortion.(4)The influence of welding sequences and initial deflection of the base plate on welding buckling distortion and residual stress is investigated.The results show that welding sequences have some influence on local buckling distortion.Initial deflection of the base plate affects the characteristics and magnitude of the global welding buckling distortion and larger initial deflection will has more obvious effect.But initial deflection of the base plate has little influence on residual stress.