Prediction of laser welding induced deformation in thin sheets by efficient numerical modeling

Abstract

A local solid model and a global shell model were employed for fast prediction of deformation in laser welded thin sheets based on inherent strain theory. Transient thermo-elastic-plastic analysis was performed on the local three-dimensional solid model to obtain inherent strain for the global shell model. To ensure solution accuracy, the characteristics of the laser welding heat source were considered in determination of the mesh size and time increment. The penetration shape of laser welded joint was well reproduced compared with the results by experimental observation. By applying inherent strain into shell element model, the out-of-plane welding deformation was predicted within a few minutes using elastic FEM. The predicted deformation mode and magnitude agreed with the measured ones for laser welded joints of different dimensions. By considering geometrical imperfection in the numerical model, it was reproduced that the laser welding induced deformation in thin sheets generally has the same mode as initial shape of the sheet.