Prediction And Control Of Welding Deformation Of Key Structures Of 20000 TEU Super Large Container Ship

Welding is the main connection means for shipbuilding.However,due to its uneven heating and cooling,the hull components produce various welding deformations.Therefore,the control of welding deformation determines the construction accuracy and efficiency of the ship to a large extent.The traditional method for predicting and controlling welding deformation is mainly based on the experience of the workers and a large number of tests,which is not only inefficient and costly,but also has been unable to adapt to complex welding structures and various welding methods.With the development of computer technology,finite element numerical calculation has become an effective means to predict welding deformation,but the thermo-elastic-plastic finite element analysis(TEP-FEA)for large complex structures takes up a lot of computer resources and takes too long.The elastic finite element analysis based on the inherent deformation is applied to the large welded structural parts,which can realize the fast and accurate prediction of the overall welding deformation of the structure.Based on the inherent deformation method,the overall welding deformation of the watertight transverse bulkhead and the torsion box structure were predicted,and various deformation control measures were proposed.Firstly,the typical welded joints were summarized and the solid element models were established respectively.The inherent strain of all joints were obtained by high-efficiency TEP-FEA,and the inherent deformation database was established.The inherent deformation was applied as a load to the welding line of the shell element model,and an elastic finite element analysis was performed to obtain the welding deformation of the overall structure quickly and accurately.In addition,it is proposed to optimize the welding sequence and optimize the welding groove to control the out-of-plane welding deformation.The results show that:(1)Through the high-efficiency TEP-FEA of 30 typical joints,the inherent deformation database is established.The accuracy of the inherent deformation is verified by comparing the results of TEP-FEA and elastic finite element analysis.Based on a large number of inherent deformation data,it is found that the heat input and the inherent deformation components are linearly increasing,and the empirical formulas are summarized.After comparison with the measured deformation data after welding,it is verified that the elastic finite element analysis based on inherent deformation can quickly and accurately predict the out-of-plane welding deformation of watertight transverse bulkhead and torsion box structure;(2)After disassembling the transverse bulkhead structure from the 2 sections into 5 sections,no matter what kind of welding sequence is used between the groups,the out-of-plane welding deformation is small.It is shown that the section is divided into more groups,which is beneficial to reduce the out-of-plane welding deformation.Through the study of the welding sequence of different segments,it is found that the out-of-plane welding deformation of the watertight transverse bulkhead structure is minimized in the order of simultaneous and symmetrical welding from the inside to the outside;(3)For the super-thick plate butt welding with the X-shaped groove,the asymmetric groove is not only beneficial to reduce the welding deformation,but also can improve the production efficiency.Through a series of high-efficiency TEP-FEA,the nonlinear relationship between the thickness of the plate(40mm?85mm)and the best front and back groove depth ratio was summarized,and the empirical formula was obtained by boltzmann fitting.Finally,the asymmetric groove with the gap is considered to be applied to the torsion box structure,and the out-of-plane welding deformation is obviously reduced.