Damage modeling in additive manufacturing processes for metals

Abstract

Metal additive manufacturing (AM) is the process of creating a metal part by selectively melting powdered metal in layers from a digital file. Metal AM revolutionizes part production, yet challenges like residual stress and distortion persist. In this study, we conduct a comprehensive quantitative analysis of the selective laser melting (SLM) process’ impact on Inconel 718 parts. The use of thermo-mechanical finite element analyses (FEA), coupled with the Johnson–Cook failure model, represents a novel approach, providing a deeper understanding of the additive manufacturing process; it captures the complex dynamics of rapid heating and solidification, exposing potential defects. The significance of this research lies in its ability to address the longstanding challenges associated with metal 3D printing. By integrating the Johnson–Cook constitutive model into a validated User Material (UMAT) subroutine in Abaqus, the study ensures robust and accurate modeling. The round tensile specimen analysis showcases a stress–strain response that aligns closely with the built-in Johnson–Cook model, demonstrating the model’s fidelity and predictive capability. The thin-walled cylinder model validates the simulation’s accuracy in predicting real-world distortions, emphasizing the practical application of the findings. Performance metrics are central to this research, with the ultimate stress at failure quantified at 0.2040 mm/mm in the tensile specimen analysis. The thin-walled cylinder model quantifies radial distortions, reaching a maximum of 0.11 mm, providing tangible performance benchmarks. Furthermore, the simulation of a bridge geometry for the SLM process predicts significant process-induced damage, offering engineers a quantitative measure of susceptibility to failure.