An inverse method for searching parameters of combined welding heat source model

Abstract

The thermo-physical parameters needed to develop accurate welding heat source models for process modelling are not always readily available and must often be developed using empirical methods or through trial and error. An inverse method based on an iterative procedure is presented in this paper, which can be used to optimize the unknown parameters in a combined welding heat source model which is composed of double-ellipsoidal and cylindrical heat sources. In the proposed method, an image of the simulated welding temperature field and the experimental weld cross-section profile of the specimen are digitalized and subtracted in order to generate the level of error between the simulated and experimental weld beads. The Hooke–Jeeves direct search method is then applied to minimize the error and optimize the parameters of interest which include radius and the width and depth and the energy partition coefficient of the combined heat source model. Thus, the parameters needed to describe a combined welding heat source model can be more efficiently obtained using the optimized parameters. The method is validated by a comparison between the measured and calculated temperature curves at a selected point in the heat affect zone.