Prediction Of Buckling Deformation In Ship Standard Platform Induced By Welding Based On Inherent Strain Theory

Welding is an important method in process of shipbuilding,the amount of welding takes more than for 75 percent of total work.The quality of ship structure and efficiency of shipbuilding are directly determined by the quality of welding.Because the weldment isn't heated uniformly due to using electric arc welding in welding operation,the welding heat-affected zone will have a great temperature gradient.Deformation occurs when the weldment is cooled to room temperature and it will change the shape and size of welding structures avoidably.When the standard platform used to carry the functional module applying thin plate structure,the welding induced buckling deformation will occur.This kind of deformation has a great impact on the accuracy.So it is necessary to predict the welding induced buckling deformation.Compared with the traditional method to predict welding deformation,the inherent strain method is faster and more efficient in calculation.In this article,based on inherent strain theory,eigenvalue analysis theory and large deformation theory,the welding induced deformation of thin plate ship structure is selected as the research subject,the main research work is as follows:Firstly,the models of the study subject is established.The thermoelastic finite element analysis is applied to simulate and analyze the welding of the typical welded joint.Then,the distribution of the plastic strain of the welding inherent strain from the post-treatment module is obtained based on the distribution of strain.And the inherent strain is studied to simulate buckling deformation induced by welding.Applying the inherent strain calculation formula,the inherent strain in different directions of the typical welded joint is studied.Secondary,according to the inherent strain loading method applied in the simulation calculation,the inherent strain calculated before is applied on the welding zone for the eigenvalue analysis of plate model and stiffened structure model,the buckling modes corresponding to welding parameters and size conditions are obtianed.Then,through the control of the variable,the influence of size,thickness,heat input,welding sequence,the number of frame member and other factors on buckling deformation is studied with the relevant conclusions,the possibility of welding induced buckling deformation based on inherent strain theory and eigenvalue analysis theory is verified.Finally,the welding induced buckling deformation of the deck structure model from the ship standard platform based on former work is studied.With the Weld-sta inherent deformation database,the inherent strain of the typical welded joints is obtained.After obtaining the inherent strain and basing on the large deformation theory,the initial deflection is introduced,the buckling mode and deformation of deck structure by nonlinear calculation are predicted.The influence of different factors such as heat input,thickness and spacing of frame member on the buckling deformation is studied by means of control variables,and the measures to control and reduce the buckling deformation are summarized.