A Gaussian Process-Based Extended Goldak Heat Source Model for Finite Element Simulation of Laser Power Bed Fusion Additive Manufacturing Process

Laser power bed fusion (L-PBF) additive manufacturing (AM) is a key enabling technology to manufacture highly complex and integrated structures. In L-PBF AM process, the melting of the metal powders and underneath layers can be governed by either “conduction mode” or “keyhole mode”. Many studies have reported that keyhole mode leads to porosity and decreased strength and ductility. Finite element simulation is often used to study the temperature distribution during printing and predict the residual stress, in which laser heat source is often applied as a volumetric heat flux based on a Gaussian or double ellipsoidal (Goldak) shape distribution. However, the above heat source models can only capture the melt pool shape in conduction melting mode, and fail to capture the transition to keyhole melting mode when the process parameters changes. To overcome the inaccuracy issue, an extended Goldak heat source model is proposed, which introduces a laser penetration term as a function of laser parameters obtained from a Gaussian-Process (GP) model. The model is validated by conducting “2D pad” AlSi10Mg L-PBF experiments under a wide range of laser power, scan speed, and laser focus offset, and the results show the model successfully captures the measured melt pool shape in all conditions.