| Abstract Scope |
Meltpool feedback control is critical for achieving consistent deposition geometry in metal AM processes such as laser DED, LPBF, and WAAM, where chaotic process conditions would otherwise produce messy parts and inconsistent builds. This control is often realized by varying the input power and monitoring the solidus isotherm in-situ, with thermal or optical cameras acting as non-contact sensors, as a surrogate for meltpool geometry. However, the resulting closed-loop systems are typically bespoke, lack generalizability, and often depend upon extensive experiential tuning. The well-known Rosenthal point-source solutions provide a bedrock understanding of steady-state meltpool behavior in AM and welding, but do not sufficiently capture isotherm dynamics to bridge from DC behavior to closed-loop design. In this paper, we lay a foundation for such a bridge by extending the Rosenthal solution in 3D to the steady-state sinusoidal-input case and developing analytical transfer function descriptions for isotherm length, width, and size (area). |