Prediction of distortion in a thin-plate structure with intermittent fillet joints using a local-to-global approach

Abstract

Fillet welds by intermittent welding are widely used in the welding of centrifugal fans, such as attaching a fan blade to the rear plate. The intermittent welding method transforms the full-length continuous weld into multiple short welds to minimize distortion by reducing the total heat input for a welded joint to control welding distortion. An infinite number of short welds are created during this process. However, depending on the complexity of the model, the computational cost of predicting welding distortion based on full-scale modeling is considerable. These numerous short welds undoubtedly complicate modeling and computations, limiting rapid distortion prediction for large and complex structures. This study develops an equivalent deformation calculation approach based on a local-to-global technique and applies it to predict distortion of a fillet joint welded specimen. The approach consists of two steps. First, the welding-induced structural deformation is calculated for a two-dimensional (2D) weld and a 2D heat-affected zone (local calculation). Second, the 2D structural deformation is applied to the full-scale welded structure using a nearest-point spatial interpolation algorithm to acquire the three-dimensional (3D) equivalent deformation (global calculation). Note that the weld shape was considered in both local and global calculations. In addition, welding tests were performed, and the coordinates of the key points were measured. The geometric parameters of the welds used in the numerical simulations were obtained from experimental observations. Finally, the key point coordinates obtained by the proposed approach were compared with experimental measurements. Furthermore, the distribution of out-of-plane distortion caused by the new approach was compared with the simulation results of the thermo-elastic-plastic method performed on a full-scale welded structure. The proposed approach can be verified by both comparisons.