A study on the spring-back deflections and constraint forces of a bottom grillage cling welding

In this paper, the welding process of a bottom grillage constrained by a pin jig is simulated through an improved thermal elasto-plastic finite element method (FEM). Shell elements with section integration are adopted to enhance simulation efficiency. The spring-back deflections after pin jig being removed and the welding deformation under unconstrained condition are calculated. The influence of mechanical restrains on the welding deformation of the bottom grillage is studied through comparison. The constraint forces of pin jig in whole welding process are obtained from the simulation. The results show that the spring-back deformation of this bottom grillage is significant and the mechanical constraints of pin jig cannot mitigate the welding distortion of this structure effectively. The maximum constraint forces of connection plate occur at the moments when welding torch approaches the adjacent structural components.