Simulation Of Welding Process For Typical Hull Components And Study On The Prediction Of Welding Deformation For Hull Blocks

Welding is the main method of shipbuilding,to a large extent,the welding quality determines the quality and efficiency of shipbuilding.The traditional hull welding process design mainly relies on a large number of welding experiments and the experience of welding workers,not only the design efficiency is low and the cost is high,but also the relationship between welding parameters and the welding property is difficult to master.At the same time,in the process of hull welding,the welding deformation not only results in the decrease of the dimension precision of the segmented structure,but also reduces the bearing capacity,moreover,the additional bending moment and stress concentration caused by the working load are the main reasons for the early failure of the hull structure.Therefore,the prediction and control of welding deformation has become an urgent problem to be solved.In view of the above problems,this paper puts forward the method of thermo elastic plastic method to the small component and inherent strain method to the large blocks,based on the thermo elastic plastic finite element method,the welding process of the typical components of the hull is simulated and analyzed,study on simulation and prediction of welding deformation of large hull blocks based on inherent strain theory.The reliability of the simulation results is verified by welding experiments,to provide theoretical guidance for the design of actual ship welding process.The main research work is as follows:(1)According to the problem of more experiments and high cost in the process of traditional making welding process,the numerical simulation of the welding process for the typical components of hull blocks based on the thermo elastic plastic finite element method is put forward.The variation laws of temperature field,deformation and stress field of multi pass welding of typical components of hull are analyzed.Designing welding experiment wih the same welding process to numerical simulation,the reliability of the simulation results is verified from two aspects of the deformation and residual stress.(2)According to the problem of lacking of effective optimization methods for welding parameters,the optimization of welding process for typical components of hull with single factor control method is put forward.Based on the analysis to the welding process of the hull,the welding process of the typical hull is simulated and optimized on the basis of the thermal elastic plastic finite element method,the influence relationshipbetween the welding speed,welding current,welding sequence and temperature field,deformation,stress field are obtained,laying the foundation for the establishment of welding parameter database.(3)According to the problem of the simulation and deformation prediction of large hull blocks welding is difficulty,based on the inherent strain method,the simulation and prediction of welding deformation of large hull blocks is put forward.Through the establishment of inherent strain database,the simulation and prediction of welding deformation of large scale and multi welded joints are realized.In order to obtain the best welding sequence,with the smallest overall deformation as the optimization target,the welding sequence of hull blocks is calculated and optimized,the reliability of the optimization results is verified by the hull blocks welding test.