Three-Dimensional Heat Transfer Modeling of Laser Beam Welding using Adaptive Volumetric Heat Source and GA based Optimization of Absorption Coefficient

An accurate estimation of the temperature field in weld pool and its surrounding area is important for a priori determination of the weld pool and heat affected zone dimensions, and the weld thermal cycle. The present work reports a finite element based three-dimensional quasi-steady heat transfer analysis for prediction of temperature field and weld dimensions in laser welding process. The novel feature introduced in the model is that a volumetric heat source term is used to account for the energy absorbed by the molten weld pool. However, the volumetric heat source is defined in an adaptive manner by mapping it with the computed weld pool dimensions such that there is no need to predefine the heat source dimensions. The heat transfer model further considers temperature dependent material properties and the latent heat of melting and solidification. The numerical heat transfer model is further integrated with a genetic algorithm (GA) based optimization tool to optimize the value of absorption coefficient that is usually not known with confidence and required to calculate the net heat input into the workpiece. The predicted weld pool dimensions from the overall integrated model are validated successfully against similar experimentally measured results reported in independent literatures for laser beam welding process.