Joule-Heated direct writing: an electrically-driven additive manufacturing paradigm for space fabrication.

The imperative for in-space manufacturing drives the development of compact, energy-efficient metal additive manufacturing (AM) technologies. This work introduces and investigates a novel Joule-Heating Additive Manufacturing (JHAM) process, inspired by the Joule-Lenz effect, for the direct writing of metallic structures. A fully coupled thermal-electrical-structural finite element model is developed to simulate the multilayer deposition of 304 stainless steel wire, elucidating the unique "tusk-shaped" temperature field evolution and the effects of current, speed, and contact width. Single-bead, five-layer walls are fabricated experimentally, and the influence of process parameters on macrostructure, geometry (width, height, overlap rate), surface roughness (Ra, Rz), and cross-sectional hardness is systematically characterized. The results demonstrate that optimal macroscopic quality is achieved at 120 A, 200 mm/min, and a 1.0 mm contact width. The forming width and overlap rate increase with current, while the forming height decreases; conversely, increasing speed reduces width and overlap but increases height. Surface roughness and hardness exhibit non-monotonic trends with varying parameters, with a minimum Ra of 0.142 µm attained. Simulated and experimentally measured voltages show good agreement, validating the multiphysics model.Validation results indicate a voltage discrepancy of less than 10% between simulation and experiment. The JHAM process, with its low power consumption (<1 kW) and simplified architecture, presents a promising candidate for on-orbit fabrication of metallic components.