Metal Additive Manufacturing Simulation Using Sequentially Coupled Thermo-Mechanical Analysis

Abstract

Additive manufacturing (AM) has become one of the most revolutionary technologies for the fabrication of metallic parts within the industry; notably, the use of existing metals has significantly eased the adoption of AM in manufacturing. The metal AM method can produce complex parts with effective cost. This process, however, involves rapid heating and solidification, resulting in a high thermal gradient. It causes undesired residual stress and distortion that significantly affects the final product’s integrity. This study investigates the features of a high thermal gradient, structural deformation, and residual stress involved in the powder bed fusion process in virtual environments. Powder bed fusion is an additive manufacturing method that uses a laser or electron beam to melt and fuse the metal material to form a three-dimensional part. A simulation model was developed using layer-to-layer scanning paths based on a 3D geometry in the 3DEXPERIENCE platform. Commercial finite element analysis (FEA) software, Abaqus CAE, is used for the sequentially coupled thermo-mechanical analysis. The temperature history is first calculated in an uncoupled thermal analysis and introduced as a predefined field in the subsequent structural analysis. In the sequentially coupled thermo-mechanical analysis, the thermal evolution of the problem affects the structural response, but the temperature field is not dependent on the stress field. Heat transfer in additive manufacturing is time-dependent, and temperature distribution in an additively manufactured part is non-uniform. Hence a time-dependent heat conduction problem is solved to analyze the process. After the thermal analysis is completed, the quasi-static equilibrium of stress is determined for each time step. An isotropic hardening rule was utilized to consider the evolution of plastic deformation.