| Abstract Scope |
Additive friction stir deposition (AFSD) is a next-generation solid-state additive manufacturing process capable of producing fully dense parts with refined microstructures and forged-like properties through extreme thermomechanical processing. This work underscores the critical role of in situ monitoring in AFSD—not only for enabling closed-loop quality control but also for uncovering the hidden process physics and mechanics. We demonstrate an integrated in situ monitoring platform that simultaneously captures tool, material, and substrate temperatures, forces, torque, heat flux, and material flow dynamics. These measurements yield key processing descriptors and reveal quantitative correlations with machine parameters such as print head rotation rate and feed rate. By coupling the in situ measurement with process modeling and Bayesian learning, we achieve unprecedented insights into the 3D intricate material flow paths, temperature/strain-rate histories of individual material voxels, and shear-driven kinetic phenomena, from which the process-structure-property relationship can be effectively bridged for widespread adoption of AFSD. |