Prediction of Welding Deformation with Inherent Strain Method Based on Finite Element Method

Inherent strain method is an economical and simply method in the prediction of the large structure’s welding deformation. Inherent strains are the residual plastic strains caused in welding process. They exist always in the welds and nearby where structures undergo a large thermal cycle, and are considered as a source causing the welding deformations. The key of using this method is how to know the inherent strains in advance during welding deformation analysis. In this document, the inherent strain is determined according to welding parameters and is first introduced with ANSYS code. At first, a simple example on the welding deformation of T-joint with two fillet welds is given with different computation methods, and then inherent strain method is applied to the welding deformation analysis of the large complex structure – GM’s Buick’s chassis underframe assembly. Inherent strains of 21 welds used for connecting the four bridges of underframe are determined and the welding deformations are computed with ANSYS. To assure the accuracy of the numerical solution, two kinds of mesh sizes are used in the analysis. Results showed that 15mm near the welds is permitted for the underframe’ welding deformation prediction. It can be concluded that ANSYS code can be used to the inherent strain method. Inherent strain method is the promising simple method in predicting the welding deformation of large complex structures. Further investigation is suggested for the instruction of practical production.

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