The Research For Prediction Of Welding Deformation Of Stiffened Panels

Welding deformation is one of the most common problems in the structural manufacturing process. Welding deformations injure the beauty of appearance of a structure and decrease its strength capability. In addition, welding deformations cause errors during the assembling of the structure and prevent increase of productivity. A kind of finite element analysis method based on inherent strain theory to predicate the welding deformation of the complicated structure is studied in this thesis. The main contents are as follows:1) A method of calculating the heat input of unit length in the direction of welding line for various welding joints and welding facilities is presented with the influence of the bead and groove being considered. The mechanism of production of main deformation modes are demonstrated .and the effects of relevant parameters are analyzed.2) The relationship between the inherent strain and welding deformation is discussed and the calculating formula of the inherent strain is derived. The value of the nonlinear elastic module is discussed in the finite element analysis, through analyzing the temperature-dependent properties of various naval materials.3) The method to calculate the dimensions of the inherent strain region of the bead on plates and stiffened panels is put forward. The calculating method of the restraint coefficients is discussed. The equivalent loads of welding line region are derived by the integration of inherent strain.4) The process of predicting welding deformations with FEA method based on the above mentioned equivalent loads is summarized. The deformations of plates and stiffened panels are calculated and compared with the results in the relevant references. The conclusion show that the method presented in this thesis is practical and prospective.